ExpressiveSharp

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[Expressive] Methods ​

Expressive methods work like expressive properties but accept parameters, making them ideal for reusable query fragments that vary based on runtime values.

Defining an Expressive Method ​

Add [Expressive] to any expression-bodied method:

csharp
using ExpressiveSharp;

public class Order
{
    public double Price { get; set; }
    public int Quantity { get; set; }
    public DateTime CreatedDate { get; set; }

    [Expressive]
    public bool IsExpensive(double threshold) => Price > threshold;
}

The source generator emits a companion Expression<Func<Order, double, bool>> at compile time. When the method is called in a LINQ query, the expression tree is substituted automatically.

The webshop entities in these samples don't have built-in [Expressive] methods, so the examples below define them as extension methods in ---setup--- blocks. The behavior is identical to instance methods.

Using Expressive Methods in Queries ​

C#
db
    .Orders
    .Where(o => o.IsExpensive(500m))
    .Select(o => new { o.Id, Expensive = o.IsExpensive(1000m) })

// Setup
public static class OrderExt
{
    [Expressive]
    public static bool IsExpensive(this Order o, decimal threshold) =>
        o.Items.Sum(i => i.UnitPrice * i.Quantity) > threshold;
}
SELECT "o"."Id", CASE
    WHEN ef_compare((
        SELECT COALESCE(ef_sum(ef_multiply("l0"."UnitPrice", CAST("l0"."Quantity" AS TEXT))), '0.0')
        FROM "LineItems" AS "l0"
        WHERE "o"."Id" = "l0"."OrderId"), '1000.0') > 0 THEN 1
    ELSE 0
END AS "Expensive"
FROM "Orders" AS "o"
WHERE ef_compare((
    SELECT COALESCE(ef_sum(ef_multiply("l"."UnitPrice", CAST("l"."Quantity" AS TEXT))), '0.0')
    FROM "LineItems" AS "l"
    WHERE "o"."Id" = "l"."OrderId"), '500.0') > 0
SELECT o."Id", CASE
    WHEN (
        SELECT COALESCE(sum(l0."UnitPrice" * l0."Quantity"::numeric(18,2)), 0.0)
        FROM "LineItems" AS l0
        WHERE o."Id" = l0."OrderId") > 1000.0 THEN TRUE
    ELSE FALSE
END AS "Expensive"
FROM "Orders" AS o
WHERE (
    SELECT COALESCE(sum(l."UnitPrice" * l."Quantity"::numeric(18,2)), 0.0)
    FROM "LineItems" AS l
    WHERE o."Id" = l."OrderId") > 500.0
SELECT [o].[Id], CASE
    WHEN (
        SELECT COALESCE(SUM([l0].[UnitPrice] * CAST([l0].[Quantity] AS decimal(18,2))), 0.0)
        FROM [LineItems] AS [l0]
        WHERE [o].[Id] = [l0].[OrderId]) > 1000.0 THEN CAST(1 AS bit)
    ELSE CAST(0 AS bit)
END AS [Expensive]
FROM [Orders] AS [o]
WHERE (
    SELECT COALESCE(SUM([l].[UnitPrice] * CAST([l].[Quantity] AS decimal(18,2))), 0.0)
    FROM [LineItems] AS [l]
    WHERE [o].[Id] = [l].[OrderId]) > 500.0
playground.orders.Aggregate([
    {
         "$match" : {
             "$expr" : {
                 "$gt" : [
                    {
                         "$sum" : {
                             "$map" : {
                                 "input" : "$Items",
                                "as" : "i",
                                "in" : {
                                     "$multiply" : ["$$i.UnitPrice", "$$i.Quantity"] 
                                } 
                            } 
                        } 
                    },
                    { "$numberDecimal" : "500" }
                ] 
            } 
        } 
    },
    {
         "$project" : {
             "_id" : "$_id",
            "Expensive" : {
                 "$gt" : [
                    {
                         "$sum" : {
                             "$map" : {
                                 "input" : "$Items",
                                "as" : "i",
                                "in" : {
                                     "$multiply" : ["$$i.UnitPrice", "$$i.Quantity"] 
                                } 
                            } 
                        } 
                    },
                    { "$numberDecimal" : "1000" }
                ] 
            } 
        } 
    }
])
// === ExpressiveSharp_Docs_Playground_Snippet_OrderExt.IsExpensive_P0_ExpressiveSharp_Docs_PlaygroundModel_Webshop_Order_P1_decimal.g.cs ===
// <auto-generated/>
#nullable disable

using System;
using System.Linq;
using System.Linq.Expressions;
using ExpressiveSharp;
using ExpressiveSharp.EntityFrameworkCore;
using ExpressiveSharp.Docs.PlaygroundModel.Webshop;
using ExpressiveSharp.Docs.Playground.Snippet;

namespace ExpressiveSharp.Generated
{
    static partial class ExpressiveSharp_Docs_Playground_Snippet_OrderExt 
    {
        // [Expressive]
        // public static bool IsExpensive(this Order o, decimal threshold) => o.Items.Sum(i => i.UnitPrice * i.Quantity) > threshold;
        static global::System.Linq.Expressions.Expression<global::System.Func<global::ExpressiveSharp.Docs.PlaygroundModel.Webshop.Order, decimal, bool>> IsExpensive_P0_ExpressiveSharp_Docs_PlaygroundModel_Webshop_Order_P1_decimal_Expression() 
        {
            var p_o = global::System.Linq.Expressions.Expression.Parameter(typeof(global::ExpressiveSharp.Docs.PlaygroundModel.Webshop.Order), "o");
            var p_threshold = global::System.Linq.Expressions.Expression.Parameter(typeof(decimal), "threshold");
            var expr_2 = global::System.Linq.Expressions.Expression.Property(p_o, typeof(global::ExpressiveSharp.Docs.PlaygroundModel.Webshop.Order).GetProperty("Items", global::System.Reflection.BindingFlags.Public | global::System.Reflection.BindingFlags.NonPublic | global::System.Reflection.BindingFlags.Instance)); // o.Items
            var p_i_3 = global::System.Linq.Expressions.Expression.Parameter(typeof(global::ExpressiveSharp.Docs.PlaygroundModel.Webshop.LineItem), "i"); // i => i.UnitPrice * i.Quantity
            var expr_5 = global::System.Linq.Expressions.Expression.Property(p_i_3, typeof(global::ExpressiveSharp.Docs.PlaygroundModel.Webshop.LineItem).GetProperty("UnitPrice", global::System.Reflection.BindingFlags.Public | global::System.Reflection.BindingFlags.NonPublic | global::System.Reflection.BindingFlags.Instance)); // i.UnitPrice
            var expr_7 = global::System.Linq.Expressions.Expression.Property(p_i_3, typeof(global::ExpressiveSharp.Docs.PlaygroundModel.Webshop.LineItem).GetProperty("Quantity", global::System.Reflection.BindingFlags.Public | global::System.Reflection.BindingFlags.NonPublic | global::System.Reflection.BindingFlags.Instance)); // i.Quantity
            var expr_6 = global::System.Linq.Expressions.Expression.Convert(expr_7, typeof(decimal));
            var expr_4 = global::System.Linq.Expressions.Expression.MakeBinary(global::System.Linq.Expressions.ExpressionType.Multiply, expr_5, expr_6);
            var expr_8 = global::System.Linq.Expressions.Expression.Lambda<global::System.Func<global::ExpressiveSharp.Docs.PlaygroundModel.Webshop.LineItem, decimal>>(expr_4, p_i_3);
            var expr_1 = global::System.Linq.Expressions.Expression.Call(global::System.Linq.Enumerable.First(global::System.Linq.Enumerable.Where(typeof(global::System.Linq.Enumerable).GetMethods(global::System.Reflection.BindingFlags.Public | global::System.Reflection.BindingFlags.NonPublic | global::System.Reflection.BindingFlags.Static), m => m.Name == "Sum" && m.IsGenericMethodDefinition && m.GetGenericArguments().Length == 1 && m.GetParameters().Length == 2 && m.GetParameters()[0].ParameterType.IsGenericType && !m.GetParameters()[0].ParameterType.IsGenericParameter && m.GetParameters()[1].ParameterType.IsGenericType && !m.GetParameters()[1].ParameterType.IsGenericParameter && m.GetParameters()[1].ParameterType.GetGenericArguments()[1] == typeof(decimal))).MakeGenericMethod(typeof(global::ExpressiveSharp.Docs.PlaygroundModel.Webshop.LineItem)), new global::System.Linq.Expressions.Expression[] { expr_2, expr_8 });
            var expr_0 = global::System.Linq.Expressions.Expression.MakeBinary(global::System.Linq.Expressions.ExpressionType.GreaterThan, expr_1, p_threshold);
            return global::System.Linq.Expressions.Expression.Lambda<global::System.Func<global::ExpressiveSharp.Docs.PlaygroundModel.Webshop.Order, decimal, bool>>(expr_0, p_o, p_threshold);
        }
    }
}


// === ExpressiveSharp_Docs_Playground_Snippet_OrderExt.Attributes.g.cs ===
// <auto-generated/>

namespace ExpressiveSharp.Generated
{
    [global::System.ComponentModel.EditorBrowsable(global::System.ComponentModel.EditorBrowsableState.Never)]
    static partial class ExpressiveSharp_Docs_Playground_Snippet_OrderExt { }
}


// === ExpressionRegistry.g.cs ===
// <auto-generated/>
#nullable disable

using System;
using System.Collections.Generic;
using System.Linq.Expressions;
using System.Reflection;

namespace ExpressiveSharp.Generated
{
    [global::System.ComponentModel.EditorBrowsable(global::System.ComponentModel.EditorBrowsableState.Never)]
    internal static class ExpressionRegistry
    {
        private static Dictionary<nint, LambdaExpression> Build()
        {
            const BindingFlags allFlags = BindingFlags.Public | BindingFlags.NonPublic | BindingFlags.Instance | BindingFlags.Static;
            var map = new Dictionary<nint, LambdaExpression>();
            
            Register(map, typeof(global::ExpressiveSharp.Docs.Playground.Snippet.OrderExt).GetMethod("IsExpensive", allFlags, null, new global::System.Type[] { typeof(global::ExpressiveSharp.Docs.PlaygroundModel.Webshop.Order), typeof(decimal) }, null), "ExpressiveSharp.Generated.ExpressiveSharp_Docs_Playground_Snippet_OrderExt", "IsExpensive_P0_ExpressiveSharp_Docs_PlaygroundModel_Webshop_Order_P1_decimal_Expression");
            
            return map;
        }
        
        private static volatile Dictionary<nint, LambdaExpression> _map = Build();
        
        internal static void ResetMap() => _map = Build();
        
        public static LambdaExpression TryGet(MemberInfo member)
        {
            var handle = member switch
            {
                MethodInfo m      => (nint?)m.MethodHandle.Value,
                PropertyInfo p    => p.GetMethod?.MethodHandle.Value,
                ConstructorInfo c => (nint?)c.MethodHandle.Value,
                _                 => null
            };
            
            return handle.HasValue && _map.TryGetValue(handle.Value, out var expr) ? expr : null;
        }
        
        private static void Register(Dictionary<nint, LambdaExpression> map, MethodBase m, string exprClass, string exprMethodName)
        {
            if (m is null) return;
            var exprType = m.DeclaringType?.Assembly.GetType(exprClass) ?? typeof(ExpressionRegistry).Assembly.GetType(exprClass);
            var exprMethod = exprType?.GetMethod(exprMethodName, BindingFlags.Static | BindingFlags.NonPublic);
            if (exprMethod is null) return;
            var expr = (LambdaExpression)exprMethod.Invoke(null, null)!;
            
            // Apply declared transformers from the generated class (if any)
            const string expressionSuffix = "_Expression";
            if (exprMethodName.EndsWith(expressionSuffix, StringComparison.Ordinal))
            {
                var transformersSuffix = exprMethodName.Substring(0, exprMethodName.Length - expressionSuffix.Length) + "_Transformers";
                var transformersMethod = exprType.GetMethod(transformersSuffix, BindingFlags.Static | BindingFlags.NonPublic);
                if (transformersMethod?.Invoke(null, null) is global::ExpressiveSharp.IExpressionTreeTransformer[] transformers)
                {
                    Expression transformed = expr;
                    foreach (var t in transformers) transformed = t.Transform(transformed);
                    if (transformed is LambdaExpression lambdaResult) expr = lambdaResult;
                }
            }
            
            map[m.MethodHandle.Value] = expr;
        }
    }
}


// === PolyfillInterceptors_b1293e61.g.cs ===
// <auto-generated/>
#nullable disable

namespace ExpressiveSharp.Generated.Interceptors
{
    internal static partial class PolyfillInterceptors
    {
        [global::System.Runtime.CompilerServices.InterceptsLocationAttribute(1, "m2hennimZySO102M4EK79qkBAABfX1NuaXBwZXQuY3M=")]
        internal static global::ExpressiveSharp.IExpressiveQueryable<T1> __Polyfill_Select_3e61_16_5<T0, T1>(
            this global::ExpressiveSharp.IExpressiveQueryable<T0> source,
            global::System.Func<T0, T1> __func)
        {
            // Source: o => new { o.Id, Expensive = o.IsExpensive(1000m) }
            var i3e6116c5_p_o = global::System.Linq.Expressions.Expression.Parameter(typeof(T0), "o");
            var i3e6116c5_expr_1 = global::System.Linq.Expressions.Expression.Property(i3e6116c5_p_o, typeof(T0).GetProperty("Id", global::System.Reflection.BindingFlags.Public | global::System.Reflection.BindingFlags.NonPublic | global::System.Reflection.BindingFlags.Instance)); // o.Id
            var i3e6116c5_expr_3 = global::System.Linq.Expressions.Expression.Constant(1000m, typeof(decimal)); // 1000m
            var i3e6116c5_expr_2 = global::System.Linq.Expressions.Expression.Call(typeof(global::ExpressiveSharp.Docs.Playground.Snippet.OrderExt).GetMethod("IsExpensive", global::System.Reflection.BindingFlags.Public | global::System.Reflection.BindingFlags.NonPublic | global::System.Reflection.BindingFlags.Static, null, new global::System.Type[] { typeof(T0), typeof(decimal) }, null), new global::System.Linq.Expressions.Expression[] { i3e6116c5_p_o, i3e6116c5_expr_3 });
            var i3e6116c5_expr_4 = typeof(T1).GetConstructors()[0];
            var i3e6116c5_expr_0 = global::System.Linq.Expressions.Expression.New(i3e6116c5_expr_4, new global::System.Linq.Expressions.Expression[] { i3e6116c5_expr_1, i3e6116c5_expr_2 }, new global::System.Reflection.MemberInfo[] { typeof(T1).GetProperty("Id"), typeof(T1).GetProperty("Expensive") });
            var __lambda = global::System.Linq.Expressions.Expression.Lambda<global::System.Func<T0, T1>>(i3e6116c5_expr_0, i3e6116c5_p_o);
            return (global::ExpressiveSharp.IExpressiveQueryable<T1>)(object)
                global::ExpressiveSharp.ExpressiveQueryableExtensions.AsExpressive(
                    global::System.Linq.Queryable.Select(
                        (global::System.Linq.IQueryable<T0>)(object)source,
                        __lambda));
        }
        [global::System.Runtime.CompilerServices.InterceptsLocationAttribute(1, "m2hennimZySO102M4EK79oQBAABfX1NuaXBwZXQuY3M=")]
        internal static global::ExpressiveSharp.IExpressiveQueryable<global::ExpressiveSharp.Docs.PlaygroundModel.Webshop.Order> __Polyfill_Where_3e61_15_5(
            this global::ExpressiveSharp.IExpressiveQueryable<global::ExpressiveSharp.Docs.PlaygroundModel.Webshop.Order> source,
            global::System.Func<global::ExpressiveSharp.Docs.PlaygroundModel.Webshop.Order, bool> __func)
        {
            // Source: o => o.IsExpensive(500m)
            var i3e6115c5_p_o = global::System.Linq.Expressions.Expression.Parameter(typeof(global::ExpressiveSharp.Docs.PlaygroundModel.Webshop.Order), "o");
            var i3e6115c5_expr_1 = global::System.Linq.Expressions.Expression.Constant(500m, typeof(decimal)); // 500m
            var i3e6115c5_expr_0 = global::System.Linq.Expressions.Expression.Call(typeof(global::ExpressiveSharp.Docs.Playground.Snippet.OrderExt).GetMethod("IsExpensive", global::System.Reflection.BindingFlags.Public | global::System.Reflection.BindingFlags.NonPublic | global::System.Reflection.BindingFlags.Static, null, new global::System.Type[] { typeof(global::ExpressiveSharp.Docs.PlaygroundModel.Webshop.Order), typeof(decimal) }, null), new global::System.Linq.Expressions.Expression[] { i3e6115c5_p_o, i3e6115c5_expr_1 });
            var __lambda = global::System.Linq.Expressions.Expression.Lambda<global::System.Func<global::ExpressiveSharp.Docs.PlaygroundModel.Webshop.Order, bool>>(i3e6115c5_expr_0, i3e6115c5_p_o);
            return global::ExpressiveSharp.ExpressiveQueryableExtensions.AsExpressive(
                global::System.Linq.Queryable.Where(
                    (global::System.Linq.IQueryable<global::ExpressiveSharp.Docs.PlaygroundModel.Webshop.Order>)source,
                    __lambda));
        }
    }
}

namespace System.Runtime.CompilerServices
{
    [global::System.AttributeUsage(global::System.AttributeTargets.Method, AllowMultiple = true)]
    file sealed class InterceptsLocationAttribute : global::System.Attribute
    {
        public InterceptsLocationAttribute(int version, string data) { }
    }
}

Open in Playground →

The method argument (500m or 1000m) is captured and translated into the generated expression for each provider.

Methods with Multiple Parameters ​

C#
db
    .Products
    .Select(p => new
    {
        p.Id,
        FinalPrice = p.CalculatePrice(0.05m, 10),
    })

// Setup
public static class ProductExt
{
    [Expressive]
    public static decimal CalculatePrice(this Product p, decimal additionalDiscount, int quantity) =>
        p.ListPrice * (1 - additionalDiscount) * quantity;
}
SELECT "p"."Id", ef_multiply(ef_multiply("p"."ListPrice", '0.95'), '10.0') AS "FinalPrice"
FROM "Products" AS "p"
SELECT p."Id", p."ListPrice" * 0.95 * 10.0 AS "FinalPrice"
FROM "Products" AS p
SELECT [p].[Id], [p].[ListPrice] * 0.95 * 10.0 AS [FinalPrice]
FROM [Products] AS [p]
playground.products.Aggregate([
    {
         "$project" : {
             "_id" : "$_id",
            "FinalPrice" : {
                 "$multiply" : [
                    "$ListPrice",
                    { "$numberDecimal" : "0.95" },
                    { "$numberDecimal" : "10" }
                ] 
            } 
        } 
    }
])
// === ExpressiveSharp_Docs_Playground_Snippet_ProductExt.CalculatePrice_P0_ExpressiveSharp_Docs_PlaygroundModel_Webshop_Product_P1_decimal_P2_int.g.cs ===
// <auto-generated/>
#nullable disable

using System;
using System.Linq;
using System.Linq.Expressions;
using ExpressiveSharp;
using ExpressiveSharp.EntityFrameworkCore;
using ExpressiveSharp.Docs.PlaygroundModel.Webshop;
using ExpressiveSharp.Docs.Playground.Snippet;

namespace ExpressiveSharp.Generated
{
    static partial class ExpressiveSharp_Docs_Playground_Snippet_ProductExt 
    {
        // [Expressive]
        // public static decimal CalculatePrice(this Product p, decimal additionalDiscount, int quantity) => p.ListPrice * (1 - additionalDiscount) * quantity;
        static global::System.Linq.Expressions.Expression<global::System.Func<global::ExpressiveSharp.Docs.PlaygroundModel.Webshop.Product, decimal, int, decimal>> CalculatePrice_P0_ExpressiveSharp_Docs_PlaygroundModel_Webshop_Product_P1_decimal_P2_int_Expression() 
        {
            var p_p = global::System.Linq.Expressions.Expression.Parameter(typeof(global::ExpressiveSharp.Docs.PlaygroundModel.Webshop.Product), "p");
            var p_additionalDiscount = global::System.Linq.Expressions.Expression.Parameter(typeof(decimal), "additionalDiscount");
            var p_quantity = global::System.Linq.Expressions.Expression.Parameter(typeof(int), "quantity");
            var expr_2 = global::System.Linq.Expressions.Expression.Property(p_p, typeof(global::ExpressiveSharp.Docs.PlaygroundModel.Webshop.Product).GetProperty("ListPrice", global::System.Reflection.BindingFlags.Public | global::System.Reflection.BindingFlags.NonPublic | global::System.Reflection.BindingFlags.Instance)); // p.ListPrice
            var expr_5 = global::System.Linq.Expressions.Expression.Constant(1, typeof(int)); // 1
            var expr_4 = global::System.Linq.Expressions.Expression.Convert(expr_5, typeof(decimal));
            var expr_3 = global::System.Linq.Expressions.Expression.MakeBinary(global::System.Linq.Expressions.ExpressionType.Subtract, expr_4, p_additionalDiscount);
            var expr_1 = global::System.Linq.Expressions.Expression.MakeBinary(global::System.Linq.Expressions.ExpressionType.Multiply, expr_2, expr_3);
            var expr_6 = global::System.Linq.Expressions.Expression.Convert(p_quantity, typeof(decimal)); // quantity
            var expr_0 = global::System.Linq.Expressions.Expression.MakeBinary(global::System.Linq.Expressions.ExpressionType.Multiply, expr_1, expr_6);
            return global::System.Linq.Expressions.Expression.Lambda<global::System.Func<global::ExpressiveSharp.Docs.PlaygroundModel.Webshop.Product, decimal, int, decimal>>(expr_0, p_p, p_additionalDiscount, p_quantity);
        }
    }
}


// === ExpressiveSharp_Docs_Playground_Snippet_ProductExt.Attributes.g.cs ===
// <auto-generated/>

namespace ExpressiveSharp.Generated
{
    [global::System.ComponentModel.EditorBrowsable(global::System.ComponentModel.EditorBrowsableState.Never)]
    static partial class ExpressiveSharp_Docs_Playground_Snippet_ProductExt { }
}


// === ExpressionRegistry.g.cs ===
// <auto-generated/>
#nullable disable

using System;
using System.Collections.Generic;
using System.Linq.Expressions;
using System.Reflection;

namespace ExpressiveSharp.Generated
{
    [global::System.ComponentModel.EditorBrowsable(global::System.ComponentModel.EditorBrowsableState.Never)]
    internal static class ExpressionRegistry
    {
        private static Dictionary<nint, LambdaExpression> Build()
        {
            const BindingFlags allFlags = BindingFlags.Public | BindingFlags.NonPublic | BindingFlags.Instance | BindingFlags.Static;
            var map = new Dictionary<nint, LambdaExpression>();
            
            Register(map, typeof(global::ExpressiveSharp.Docs.Playground.Snippet.ProductExt).GetMethod("CalculatePrice", allFlags, null, new global::System.Type[] { typeof(global::ExpressiveSharp.Docs.PlaygroundModel.Webshop.Product), typeof(decimal), typeof(int) }, null), "ExpressiveSharp.Generated.ExpressiveSharp_Docs_Playground_Snippet_ProductExt", "CalculatePrice_P0_ExpressiveSharp_Docs_PlaygroundModel_Webshop_Product_P1_decimal_P2_int_Expression");
            
            return map;
        }
        
        private static volatile Dictionary<nint, LambdaExpression> _map = Build();
        
        internal static void ResetMap() => _map = Build();
        
        public static LambdaExpression TryGet(MemberInfo member)
        {
            var handle = member switch
            {
                MethodInfo m      => (nint?)m.MethodHandle.Value,
                PropertyInfo p    => p.GetMethod?.MethodHandle.Value,
                ConstructorInfo c => (nint?)c.MethodHandle.Value,
                _                 => null
            };
            
            return handle.HasValue && _map.TryGetValue(handle.Value, out var expr) ? expr : null;
        }
        
        private static void Register(Dictionary<nint, LambdaExpression> map, MethodBase m, string exprClass, string exprMethodName)
        {
            if (m is null) return;
            var exprType = m.DeclaringType?.Assembly.GetType(exprClass) ?? typeof(ExpressionRegistry).Assembly.GetType(exprClass);
            var exprMethod = exprType?.GetMethod(exprMethodName, BindingFlags.Static | BindingFlags.NonPublic);
            if (exprMethod is null) return;
            var expr = (LambdaExpression)exprMethod.Invoke(null, null)!;
            
            // Apply declared transformers from the generated class (if any)
            const string expressionSuffix = "_Expression";
            if (exprMethodName.EndsWith(expressionSuffix, StringComparison.Ordinal))
            {
                var transformersSuffix = exprMethodName.Substring(0, exprMethodName.Length - expressionSuffix.Length) + "_Transformers";
                var transformersMethod = exprType.GetMethod(transformersSuffix, BindingFlags.Static | BindingFlags.NonPublic);
                if (transformersMethod?.Invoke(null, null) is global::ExpressiveSharp.IExpressionTreeTransformer[] transformers)
                {
                    Expression transformed = expr;
                    foreach (var t in transformers) transformed = t.Transform(transformed);
                    if (transformed is LambdaExpression lambdaResult) expr = lambdaResult;
                }
            }
            
            map[m.MethodHandle.Value] = expr;
        }
    }
}


// === PolyfillInterceptors_b1293e61.g.cs ===
// <auto-generated/>
#nullable disable

namespace ExpressiveSharp.Generated.Interceptors
{
    internal static partial class PolyfillInterceptors
    {
        [global::System.Runtime.CompilerServices.InterceptsLocationAttribute(1, "hth0NIpv8oSj11LlGWmpxoEBAABfX1NuaXBwZXQuY3M=")]
        internal static global::ExpressiveSharp.IExpressiveQueryable<T1> __Polyfill_Select_3e61_14_23<T0, T1>(
            this global::ExpressiveSharp.IExpressiveQueryable<T0> source,
            global::System.Func<T0, T1> __func)
        {
            // Source: p => new { p.Id, FinalPrice = p.CalculatePrice(0.05m, 10), }
            var i3e6114c23_p_p = global::System.Linq.Expressions.Expression.Parameter(typeof(T0), "p");
            var i3e6114c23_expr_1 = global::System.Linq.Expressions.Expression.Property(i3e6114c23_p_p, typeof(T0).GetProperty("Id", global::System.Reflection.BindingFlags.Public | global::System.Reflection.BindingFlags.NonPublic | global::System.Reflection.BindingFlags.Instance)); // p.Id
            var i3e6114c23_expr_3 = global::System.Linq.Expressions.Expression.Constant(0.05m, typeof(decimal)); // 0.05m
            var i3e6114c23_expr_4 = global::System.Linq.Expressions.Expression.Constant(10, typeof(int)); // 10
            var i3e6114c23_expr_2 = global::System.Linq.Expressions.Expression.Call(typeof(global::ExpressiveSharp.Docs.Playground.Snippet.ProductExt).GetMethod("CalculatePrice", global::System.Reflection.BindingFlags.Public | global::System.Reflection.BindingFlags.NonPublic | global::System.Reflection.BindingFlags.Static, null, new global::System.Type[] { typeof(T0), typeof(decimal), typeof(int) }, null), new global::System.Linq.Expressions.Expression[] { i3e6114c23_p_p, i3e6114c23_expr_3, i3e6114c23_expr_4 });
            var i3e6114c23_expr_5 = typeof(T1).GetConstructors()[0];
            var i3e6114c23_expr_0 = global::System.Linq.Expressions.Expression.New(i3e6114c23_expr_5, new global::System.Linq.Expressions.Expression[] { i3e6114c23_expr_1, i3e6114c23_expr_2 }, new global::System.Reflection.MemberInfo[] { typeof(T1).GetProperty("Id"), typeof(T1).GetProperty("FinalPrice") });
            var __lambda = global::System.Linq.Expressions.Expression.Lambda<global::System.Func<T0, T1>>(i3e6114c23_expr_0, i3e6114c23_p_p);
            return (global::ExpressiveSharp.IExpressiveQueryable<T1>)(object)
                global::ExpressiveSharp.ExpressiveQueryableExtensions.AsExpressive(
                    global::System.Linq.Queryable.Select(
                        (global::System.Linq.IQueryable<T0>)(object)source,
                        __lambda));
        }
    }
}

namespace System.Runtime.CompilerServices
{
    [global::System.AttributeUsage(global::System.AttributeTargets.Method, AllowMultiple = true)]
    file sealed class InterceptsLocationAttribute : global::System.Attribute
    {
        public InterceptsLocationAttribute(int version, string data) { }
    }
}

Open in Playground →

Switch Expressions in Methods ​

Switch expressions and pattern matching work inside [Expressive] methods -- this is one of the key features that plain expression trees cannot do:

C#
db
    .Orders
    .Select(o => new { o.Id, Grade = o.GetGrade() })

// Setup
public static class OrderExt
{
    [Expressive]
    public static string GetGrade(this Order o) =>
        o.Items.Sum(i => i.UnitPrice * i.Quantity) switch
        {
            >= 100m => "Premium",
            >= 50m  => "Standard",
            _       => "Budget",
        };
}
SELECT "o"."Id", CASE
    WHEN ef_compare((
        SELECT COALESCE(ef_sum(ef_multiply("l"."UnitPrice", CAST("l"."Quantity" AS TEXT))), '0.0')
        FROM "LineItems" AS "l"
        WHERE "o"."Id" = "l"."OrderId"), '100.0') >= 0 THEN 'Premium'
    WHEN ef_compare((
        SELECT COALESCE(ef_sum(ef_multiply("l0"."UnitPrice", CAST("l0"."Quantity" AS TEXT))), '0.0')
        FROM "LineItems" AS "l0"
        WHERE "o"."Id" = "l0"."OrderId"), '50.0') >= 0 THEN 'Standard'
    ELSE 'Budget'
END AS "Grade"
FROM "Orders" AS "o"
SELECT o."Id", CASE
    WHEN (
        SELECT COALESCE(sum(l."UnitPrice" * l."Quantity"::numeric(18,2)), 0.0)
        FROM "LineItems" AS l
        WHERE o."Id" = l."OrderId") >= 100.0 THEN 'Premium'
    WHEN (
        SELECT COALESCE(sum(l0."UnitPrice" * l0."Quantity"::numeric(18,2)), 0.0)
        FROM "LineItems" AS l0
        WHERE o."Id" = l0."OrderId") >= 50.0 THEN 'Standard'
    ELSE 'Budget'
END AS "Grade"
FROM "Orders" AS o
SELECT [o].[Id], CASE
    WHEN (
        SELECT COALESCE(SUM([l].[UnitPrice] * CAST([l].[Quantity] AS decimal(18,2))), 0.0)
        FROM [LineItems] AS [l]
        WHERE [o].[Id] = [l].[OrderId]) >= 100.0 THEN N'Premium'
    WHEN (
        SELECT COALESCE(SUM([l0].[UnitPrice] * CAST([l0].[Quantity] AS decimal(18,2))), 0.0)
        FROM [LineItems] AS [l0]
        WHERE [o].[Id] = [l0].[OrderId]) >= 50.0 THEN N'Standard'
    ELSE N'Budget'
END AS [Grade]
FROM [Orders] AS [o]
playground.orders.Aggregate([
    {
         "$project" : {
             "_id" : "$_id",
            "Grade" : {
                 "$cond" : {
                     "if" : {
                         "$gte" : [
                            {
                                 "$sum" : {
                                     "$map" : {
                                         "input" : "$Items",
                                        "as" : "i",
                                        "in" : {
                                             "$multiply" : ["$$i.UnitPrice", "$$i.Quantity"] 
                                        } 
                                    } 
                                } 
                            },
                            { "$numberDecimal" : "100" }
                        ] 
                    },
                    "then" : "Premium",
                    "else" : {
                         "$cond" : {
                             "if" : {
                                 "$gte" : [
                                    {
                                         "$sum" : {
                                             "$map" : {
                                                 "input" : "$Items",
                                                "as" : "i",
                                                "in" : {
                                                     "$multiply" : ["$$i.UnitPrice", "$$i.Quantity"] 
                                                } 
                                            } 
                                        } 
                                    },
                                    { "$numberDecimal" : "50" }
                                ] 
                            },
                            "then" : "Standard",
                            "else" : "Budget" 
                        } 
                    } 
                } 
            } 
        } 
    }
])
// === ExpressiveSharp_Docs_Playground_Snippet_OrderExt.GetGrade_P0_ExpressiveSharp_Docs_PlaygroundModel_Webshop_Order.g.cs ===
// <auto-generated/>
#nullable disable

using System;
using System.Linq;
using System.Linq.Expressions;
using ExpressiveSharp;
using ExpressiveSharp.EntityFrameworkCore;
using ExpressiveSharp.Docs.PlaygroundModel.Webshop;
using ExpressiveSharp.Docs.Playground.Snippet;

namespace ExpressiveSharp.Generated
{
    static partial class ExpressiveSharp_Docs_Playground_Snippet_OrderExt 
    {
        // [Expressive]
        // public static string GetGrade(this Order o) => o.Items.Sum(i => i.UnitPrice * i.Quantity) switch
        // {
        //     >= 100m => "Premium",
        //     >= 50m => "Standard",
        //     _ => "Budget",
        // };
        static global::System.Linq.Expressions.Expression<global::System.Func<global::ExpressiveSharp.Docs.PlaygroundModel.Webshop.Order, string>> GetGrade_P0_ExpressiveSharp_Docs_PlaygroundModel_Webshop_Order_Expression() 
        {
            var p_o = global::System.Linq.Expressions.Expression.Parameter(typeof(global::ExpressiveSharp.Docs.PlaygroundModel.Webshop.Order), "o");
            var expr_1 = global::System.Linq.Expressions.Expression.Property(p_o, typeof(global::ExpressiveSharp.Docs.PlaygroundModel.Webshop.Order).GetProperty("Items", global::System.Reflection.BindingFlags.Public | global::System.Reflection.BindingFlags.NonPublic | global::System.Reflection.BindingFlags.Instance)); // o.Items
            var p_i_2 = global::System.Linq.Expressions.Expression.Parameter(typeof(global::ExpressiveSharp.Docs.PlaygroundModel.Webshop.LineItem), "i"); // i => i.UnitPrice * i.Quantity
            var expr_4 = global::System.Linq.Expressions.Expression.Property(p_i_2, typeof(global::ExpressiveSharp.Docs.PlaygroundModel.Webshop.LineItem).GetProperty("UnitPrice", global::System.Reflection.BindingFlags.Public | global::System.Reflection.BindingFlags.NonPublic | global::System.Reflection.BindingFlags.Instance)); // i.UnitPrice
            var expr_6 = global::System.Linq.Expressions.Expression.Property(p_i_2, typeof(global::ExpressiveSharp.Docs.PlaygroundModel.Webshop.LineItem).GetProperty("Quantity", global::System.Reflection.BindingFlags.Public | global::System.Reflection.BindingFlags.NonPublic | global::System.Reflection.BindingFlags.Instance)); // i.Quantity
            var expr_5 = global::System.Linq.Expressions.Expression.Convert(expr_6, typeof(decimal));
            var expr_3 = global::System.Linq.Expressions.Expression.MakeBinary(global::System.Linq.Expressions.ExpressionType.Multiply, expr_4, expr_5);
            var expr_7 = global::System.Linq.Expressions.Expression.Lambda<global::System.Func<global::ExpressiveSharp.Docs.PlaygroundModel.Webshop.LineItem, decimal>>(expr_3, p_i_2);
            var expr_0 = global::System.Linq.Expressions.Expression.Call(global::System.Linq.Enumerable.First(global::System.Linq.Enumerable.Where(typeof(global::System.Linq.Enumerable).GetMethods(global::System.Reflection.BindingFlags.Public | global::System.Reflection.BindingFlags.NonPublic | global::System.Reflection.BindingFlags.Static), m => m.Name == "Sum" && m.IsGenericMethodDefinition && m.GetGenericArguments().Length == 1 && m.GetParameters().Length == 2 && m.GetParameters()[0].ParameterType.IsGenericType && !m.GetParameters()[0].ParameterType.IsGenericParameter && m.GetParameters()[1].ParameterType.IsGenericType && !m.GetParameters()[1].ParameterType.IsGenericParameter && m.GetParameters()[1].ParameterType.GetGenericArguments()[1] == typeof(decimal))).MakeGenericMethod(typeof(global::ExpressiveSharp.Docs.PlaygroundModel.Webshop.LineItem)), new global::System.Linq.Expressions.Expression[] { expr_1, expr_7 });
            var expr_8 = global::System.Linq.Expressions.Expression.Constant("Budget", typeof(string)); // "Budget"
            var expr_10 = global::System.Linq.Expressions.Expression.Constant(50m, typeof(decimal)); // 50m
            var expr_9 = global::System.Linq.Expressions.Expression.MakeBinary(global::System.Linq.Expressions.ExpressionType.GreaterThanOrEqual, expr_0, expr_10);
            var expr_11 = global::System.Linq.Expressions.Expression.Constant("Standard", typeof(string)); // "Standard"
            var expr_12 = global::System.Linq.Expressions.Expression.Condition(expr_9, expr_11, expr_8, typeof(string));
            var expr_14 = global::System.Linq.Expressions.Expression.Constant(100m, typeof(decimal)); // 100m
            var expr_13 = global::System.Linq.Expressions.Expression.MakeBinary(global::System.Linq.Expressions.ExpressionType.GreaterThanOrEqual, expr_0, expr_14);
            var expr_15 = global::System.Linq.Expressions.Expression.Constant("Premium", typeof(string)); // "Premium"
            var expr_16 = global::System.Linq.Expressions.Expression.Condition(expr_13, expr_15, expr_12, typeof(string));
            return global::System.Linq.Expressions.Expression.Lambda<global::System.Func<global::ExpressiveSharp.Docs.PlaygroundModel.Webshop.Order, string>>(expr_16, p_o);
        }
    }
}


// === ExpressiveSharp_Docs_Playground_Snippet_OrderExt.Attributes.g.cs ===
// <auto-generated/>

namespace ExpressiveSharp.Generated
{
    [global::System.ComponentModel.EditorBrowsable(global::System.ComponentModel.EditorBrowsableState.Never)]
    static partial class ExpressiveSharp_Docs_Playground_Snippet_OrderExt { }
}


// === ExpressionRegistry.g.cs ===
// <auto-generated/>
#nullable disable

using System;
using System.Collections.Generic;
using System.Linq.Expressions;
using System.Reflection;

namespace ExpressiveSharp.Generated
{
    [global::System.ComponentModel.EditorBrowsable(global::System.ComponentModel.EditorBrowsableState.Never)]
    internal static class ExpressionRegistry
    {
        private static Dictionary<nint, LambdaExpression> Build()
        {
            const BindingFlags allFlags = BindingFlags.Public | BindingFlags.NonPublic | BindingFlags.Instance | BindingFlags.Static;
            var map = new Dictionary<nint, LambdaExpression>();
            
            Register(map, typeof(global::ExpressiveSharp.Docs.Playground.Snippet.OrderExt).GetMethod("GetGrade", allFlags, null, new global::System.Type[] { typeof(global::ExpressiveSharp.Docs.PlaygroundModel.Webshop.Order) }, null), "ExpressiveSharp.Generated.ExpressiveSharp_Docs_Playground_Snippet_OrderExt", "GetGrade_P0_ExpressiveSharp_Docs_PlaygroundModel_Webshop_Order_Expression");
            
            return map;
        }
        
        private static volatile Dictionary<nint, LambdaExpression> _map = Build();
        
        internal static void ResetMap() => _map = Build();
        
        public static LambdaExpression TryGet(MemberInfo member)
        {
            var handle = member switch
            {
                MethodInfo m      => (nint?)m.MethodHandle.Value,
                PropertyInfo p    => p.GetMethod?.MethodHandle.Value,
                ConstructorInfo c => (nint?)c.MethodHandle.Value,
                _                 => null
            };
            
            return handle.HasValue && _map.TryGetValue(handle.Value, out var expr) ? expr : null;
        }
        
        private static void Register(Dictionary<nint, LambdaExpression> map, MethodBase m, string exprClass, string exprMethodName)
        {
            if (m is null) return;
            var exprType = m.DeclaringType?.Assembly.GetType(exprClass) ?? typeof(ExpressionRegistry).Assembly.GetType(exprClass);
            var exprMethod = exprType?.GetMethod(exprMethodName, BindingFlags.Static | BindingFlags.NonPublic);
            if (exprMethod is null) return;
            var expr = (LambdaExpression)exprMethod.Invoke(null, null)!;
            
            // Apply declared transformers from the generated class (if any)
            const string expressionSuffix = "_Expression";
            if (exprMethodName.EndsWith(expressionSuffix, StringComparison.Ordinal))
            {
                var transformersSuffix = exprMethodName.Substring(0, exprMethodName.Length - expressionSuffix.Length) + "_Transformers";
                var transformersMethod = exprType.GetMethod(transformersSuffix, BindingFlags.Static | BindingFlags.NonPublic);
                if (transformersMethod?.Invoke(null, null) is global::ExpressiveSharp.IExpressionTreeTransformer[] transformers)
                {
                    Expression transformed = expr;
                    foreach (var t in transformers) transformed = t.Transform(transformed);
                    if (transformed is LambdaExpression lambdaResult) expr = lambdaResult;
                }
            }
            
            map[m.MethodHandle.Value] = expr;
        }
    }
}


// === PolyfillInterceptors_b1293e61.g.cs ===
// <auto-generated/>
#nullable disable

namespace ExpressiveSharp.Generated.Interceptors
{
    internal static partial class PolyfillInterceptors
    {
        [global::System.Runtime.CompilerServices.InterceptsLocationAttribute(1, "diP8kLHm4S5IfpgEmLWIrn8BAABfX1NuaXBwZXQuY3M=")]
        internal static global::ExpressiveSharp.IExpressiveQueryable<T1> __Polyfill_Select_3e61_14_21<T0, T1>(
            this global::ExpressiveSharp.IExpressiveQueryable<T0> source,
            global::System.Func<T0, T1> __func)
        {
            // Source: o => new { o.Id, Grade = o.GetGrade() }
            var i3e6114c21_p_o = global::System.Linq.Expressions.Expression.Parameter(typeof(T0), "o");
            var i3e6114c21_expr_1 = global::System.Linq.Expressions.Expression.Property(i3e6114c21_p_o, typeof(T0).GetProperty("Id", global::System.Reflection.BindingFlags.Public | global::System.Reflection.BindingFlags.NonPublic | global::System.Reflection.BindingFlags.Instance)); // o.Id
            var i3e6114c21_expr_2 = global::System.Linq.Expressions.Expression.Call(typeof(global::ExpressiveSharp.Docs.Playground.Snippet.OrderExt).GetMethod("GetGrade", global::System.Reflection.BindingFlags.Public | global::System.Reflection.BindingFlags.NonPublic | global::System.Reflection.BindingFlags.Static, null, new global::System.Type[] { typeof(T0) }, null), new global::System.Linq.Expressions.Expression[] { i3e6114c21_p_o }); // o.GetGrade()
            var i3e6114c21_expr_3 = typeof(T1).GetConstructors()[0];
            var i3e6114c21_expr_0 = global::System.Linq.Expressions.Expression.New(i3e6114c21_expr_3, new global::System.Linq.Expressions.Expression[] { i3e6114c21_expr_1, i3e6114c21_expr_2 }, new global::System.Reflection.MemberInfo[] { typeof(T1).GetProperty("Id"), typeof(T1).GetProperty("Grade") });
            var __lambda = global::System.Linq.Expressions.Expression.Lambda<global::System.Func<T0, T1>>(i3e6114c21_expr_0, i3e6114c21_p_o);
            return (global::ExpressiveSharp.IExpressiveQueryable<T1>)(object)
                global::ExpressiveSharp.ExpressiveQueryableExtensions.AsExpressive(
                    global::System.Linq.Queryable.Select(
                        (global::System.Linq.IQueryable<T0>)(object)source,
                        __lambda));
        }
    }
}

namespace System.Runtime.CompilerServices
{
    [global::System.AttributeUsage(global::System.AttributeTargets.Method, AllowMultiple = true)]
    file sealed class InterceptsLocationAttribute : global::System.Attribute
    {
        public InterceptsLocationAttribute(int version, string data) { }
    }
}

Open in Playground →

The query tabs above show how each provider translates the switch expression (typically as a CASE expression for SQL providers).

Composing Methods and Properties ​

Expressive methods can call other expressive members and vice versa. The runtime expander resolves the entire chain:

C#
db
    .Orders
    .Where(o => o.ExceedsThreshold(500m))
    .Select(o => o.Id)

// Setup
public static class OrderExt
{
    [Expressive]
    public static decimal Subtotal(this Order o) =>
        o.Items.Sum(i => i.UnitPrice * i.Quantity);

    [Expressive]
    public static decimal Tax(this Order o, decimal rate) =>
        o.Subtotal() * rate;

    [Expressive]
    public static bool ExceedsThreshold(this Order o, decimal threshold) =>
        (o.Subtotal() + o.Tax(0.21m)) > threshold;
}
SELECT "o"."Id"
FROM "Orders" AS "o"
WHERE ef_compare(ef_add((
    SELECT COALESCE(ef_sum(ef_multiply("l"."UnitPrice", CAST("l"."Quantity" AS TEXT))), '0.0')
    FROM "LineItems" AS "l"
    WHERE "o"."Id" = "l"."OrderId"), ef_multiply((
    SELECT COALESCE(ef_sum(ef_multiply("l0"."UnitPrice", CAST("l0"."Quantity" AS TEXT))), '0.0')
    FROM "LineItems" AS "l0"
    WHERE "o"."Id" = "l0"."OrderId"), '0.21')), '500.0') > 0
SELECT o."Id"
FROM "Orders" AS o
WHERE (
    SELECT COALESCE(sum(l."UnitPrice" * l."Quantity"::numeric(18,2)), 0.0)
    FROM "LineItems" AS l
    WHERE o."Id" = l."OrderId") + (
    SELECT COALESCE(sum(l0."UnitPrice" * l0."Quantity"::numeric(18,2)), 0.0)
    FROM "LineItems" AS l0
    WHERE o."Id" = l0."OrderId") * 0.21 > 500.0
SELECT [o].[Id]
FROM [Orders] AS [o]
WHERE (
    SELECT COALESCE(SUM([l].[UnitPrice] * CAST([l].[Quantity] AS decimal(18,2))), 0.0)
    FROM [LineItems] AS [l]
    WHERE [o].[Id] = [l].[OrderId]) + (
    SELECT COALESCE(SUM([l0].[UnitPrice] * CAST([l0].[Quantity] AS decimal(18,2))), 0.0)
    FROM [LineItems] AS [l0]
    WHERE [o].[Id] = [l0].[OrderId]) * 0.21 > 500.0
playground.orders.Aggregate([
    {
         "$match" : {
             "$expr" : {
                 "$gt" : [
                    {
                         "$add" : [
                            {
                                 "$sum" : {
                                     "$map" : {
                                         "input" : "$Items",
                                        "as" : "i",
                                        "in" : {
                                             "$multiply" : ["$$i.UnitPrice", "$$i.Quantity"] 
                                        } 
                                    } 
                                } 
                            },
                            {
                                 "$multiply" : [
                                    {
                                         "$sum" : {
                                             "$map" : {
                                                 "input" : "$Items",
                                                "as" : "i",
                                                "in" : {
                                                     "$multiply" : ["$$i.UnitPrice", "$$i.Quantity"] 
                                                } 
                                            } 
                                        } 
                                    },
                                    { "$numberDecimal" : "0.21" }
                                ] 
                            }
                        ] 
                    },
                    { "$numberDecimal" : "500" }
                ] 
            } 
        } 
    },
    {
         "$project" : { "_v" : "$_id", "_id" : 0 } 
    }
])
// === ExpressiveSharp_Docs_Playground_Snippet_OrderExt.Subtotal_P0_ExpressiveSharp_Docs_PlaygroundModel_Webshop_Order.g.cs ===
// <auto-generated/>
#nullable disable

using System;
using System.Linq;
using System.Linq.Expressions;
using ExpressiveSharp;
using ExpressiveSharp.EntityFrameworkCore;
using ExpressiveSharp.Docs.PlaygroundModel.Webshop;
using ExpressiveSharp.Docs.Playground.Snippet;

namespace ExpressiveSharp.Generated
{
    static partial class ExpressiveSharp_Docs_Playground_Snippet_OrderExt 
    {
        // [Expressive]
        // public static decimal Subtotal(this Order o) => o.Items.Sum(i => i.UnitPrice * i.Quantity);
        static global::System.Linq.Expressions.Expression<global::System.Func<global::ExpressiveSharp.Docs.PlaygroundModel.Webshop.Order, decimal>> Subtotal_P0_ExpressiveSharp_Docs_PlaygroundModel_Webshop_Order_Expression() 
        {
            var p_o = global::System.Linq.Expressions.Expression.Parameter(typeof(global::ExpressiveSharp.Docs.PlaygroundModel.Webshop.Order), "o");
            var expr_1 = global::System.Linq.Expressions.Expression.Property(p_o, typeof(global::ExpressiveSharp.Docs.PlaygroundModel.Webshop.Order).GetProperty("Items", global::System.Reflection.BindingFlags.Public | global::System.Reflection.BindingFlags.NonPublic | global::System.Reflection.BindingFlags.Instance)); // o.Items
            var p_i_2 = global::System.Linq.Expressions.Expression.Parameter(typeof(global::ExpressiveSharp.Docs.PlaygroundModel.Webshop.LineItem), "i"); // i => i.UnitPrice * i.Quantity
            var expr_4 = global::System.Linq.Expressions.Expression.Property(p_i_2, typeof(global::ExpressiveSharp.Docs.PlaygroundModel.Webshop.LineItem).GetProperty("UnitPrice", global::System.Reflection.BindingFlags.Public | global::System.Reflection.BindingFlags.NonPublic | global::System.Reflection.BindingFlags.Instance)); // i.UnitPrice
            var expr_6 = global::System.Linq.Expressions.Expression.Property(p_i_2, typeof(global::ExpressiveSharp.Docs.PlaygroundModel.Webshop.LineItem).GetProperty("Quantity", global::System.Reflection.BindingFlags.Public | global::System.Reflection.BindingFlags.NonPublic | global::System.Reflection.BindingFlags.Instance)); // i.Quantity
            var expr_5 = global::System.Linq.Expressions.Expression.Convert(expr_6, typeof(decimal));
            var expr_3 = global::System.Linq.Expressions.Expression.MakeBinary(global::System.Linq.Expressions.ExpressionType.Multiply, expr_4, expr_5);
            var expr_7 = global::System.Linq.Expressions.Expression.Lambda<global::System.Func<global::ExpressiveSharp.Docs.PlaygroundModel.Webshop.LineItem, decimal>>(expr_3, p_i_2);
            var expr_0 = global::System.Linq.Expressions.Expression.Call(global::System.Linq.Enumerable.First(global::System.Linq.Enumerable.Where(typeof(global::System.Linq.Enumerable).GetMethods(global::System.Reflection.BindingFlags.Public | global::System.Reflection.BindingFlags.NonPublic | global::System.Reflection.BindingFlags.Static), m => m.Name == "Sum" && m.IsGenericMethodDefinition && m.GetGenericArguments().Length == 1 && m.GetParameters().Length == 2 && m.GetParameters()[0].ParameterType.IsGenericType && !m.GetParameters()[0].ParameterType.IsGenericParameter && m.GetParameters()[1].ParameterType.IsGenericType && !m.GetParameters()[1].ParameterType.IsGenericParameter && m.GetParameters()[1].ParameterType.GetGenericArguments()[1] == typeof(decimal))).MakeGenericMethod(typeof(global::ExpressiveSharp.Docs.PlaygroundModel.Webshop.LineItem)), new global::System.Linq.Expressions.Expression[] { expr_1, expr_7 });
            return global::System.Linq.Expressions.Expression.Lambda<global::System.Func<global::ExpressiveSharp.Docs.PlaygroundModel.Webshop.Order, decimal>>(expr_0, p_o);
        }
    }
}


// === ExpressiveSharp_Docs_Playground_Snippet_OrderExt.Tax_P0_ExpressiveSharp_Docs_PlaygroundModel_Webshop_Order_P1_decimal.g.cs ===
// <auto-generated/>
#nullable disable

using System;
using System.Linq;
using System.Linq.Expressions;
using ExpressiveSharp;
using ExpressiveSharp.EntityFrameworkCore;
using ExpressiveSharp.Docs.PlaygroundModel.Webshop;
using ExpressiveSharp.Docs.Playground.Snippet;

namespace ExpressiveSharp.Generated
{
    static partial class ExpressiveSharp_Docs_Playground_Snippet_OrderExt 
    {
        // [Expressive]
        // public static decimal Tax(this Order o, decimal rate) => o.Subtotal() * rate;
        static global::System.Linq.Expressions.Expression<global::System.Func<global::ExpressiveSharp.Docs.PlaygroundModel.Webshop.Order, decimal, decimal>> Tax_P0_ExpressiveSharp_Docs_PlaygroundModel_Webshop_Order_P1_decimal_Expression() 
        {
            var p_o = global::System.Linq.Expressions.Expression.Parameter(typeof(global::ExpressiveSharp.Docs.PlaygroundModel.Webshop.Order), "o");
            var p_rate = global::System.Linq.Expressions.Expression.Parameter(typeof(decimal), "rate");
            var expr_1 = global::System.Linq.Expressions.Expression.Call(typeof(global::ExpressiveSharp.Docs.Playground.Snippet.OrderExt).GetMethod("Subtotal", global::System.Reflection.BindingFlags.Public | global::System.Reflection.BindingFlags.NonPublic | global::System.Reflection.BindingFlags.Static, null, new global::System.Type[] { typeof(global::ExpressiveSharp.Docs.PlaygroundModel.Webshop.Order) }, null), new global::System.Linq.Expressions.Expression[] { p_o }); // o.Subtotal()
            var expr_0 = global::System.Linq.Expressions.Expression.MakeBinary(global::System.Linq.Expressions.ExpressionType.Multiply, expr_1, p_rate);
            return global::System.Linq.Expressions.Expression.Lambda<global::System.Func<global::ExpressiveSharp.Docs.PlaygroundModel.Webshop.Order, decimal, decimal>>(expr_0, p_o, p_rate);
        }
    }
}


// === ExpressiveSharp_Docs_Playground_Snippet_OrderExt.ExceedsThreshold_P0_ExpressiveSharp_Docs_PlaygroundModel_Webshop_Order_P1_decimal.g.cs ===
// <auto-generated/>
#nullable disable

using System;
using System.Linq;
using System.Linq.Expressions;
using ExpressiveSharp;
using ExpressiveSharp.EntityFrameworkCore;
using ExpressiveSharp.Docs.PlaygroundModel.Webshop;
using ExpressiveSharp.Docs.Playground.Snippet;

namespace ExpressiveSharp.Generated
{
    static partial class ExpressiveSharp_Docs_Playground_Snippet_OrderExt 
    {
        // [Expressive]
        // public static bool ExceedsThreshold(this Order o, decimal threshold) => (o.Subtotal() + o.Tax(0.21m)) > threshold;
        static global::System.Linq.Expressions.Expression<global::System.Func<global::ExpressiveSharp.Docs.PlaygroundModel.Webshop.Order, decimal, bool>> ExceedsThreshold_P0_ExpressiveSharp_Docs_PlaygroundModel_Webshop_Order_P1_decimal_Expression() 
        {
            var p_o = global::System.Linq.Expressions.Expression.Parameter(typeof(global::ExpressiveSharp.Docs.PlaygroundModel.Webshop.Order), "o");
            var p_threshold = global::System.Linq.Expressions.Expression.Parameter(typeof(decimal), "threshold");
            var expr_2 = global::System.Linq.Expressions.Expression.Call(typeof(global::ExpressiveSharp.Docs.Playground.Snippet.OrderExt).GetMethod("Subtotal", global::System.Reflection.BindingFlags.Public | global::System.Reflection.BindingFlags.NonPublic | global::System.Reflection.BindingFlags.Static, null, new global::System.Type[] { typeof(global::ExpressiveSharp.Docs.PlaygroundModel.Webshop.Order) }, null), new global::System.Linq.Expressions.Expression[] { p_o }); // o.Subtotal()
            var expr_4 = global::System.Linq.Expressions.Expression.Constant(0.21m, typeof(decimal)); // 0.21m
            var expr_3 = global::System.Linq.Expressions.Expression.Call(typeof(global::ExpressiveSharp.Docs.Playground.Snippet.OrderExt).GetMethod("Tax", global::System.Reflection.BindingFlags.Public | global::System.Reflection.BindingFlags.NonPublic | global::System.Reflection.BindingFlags.Static, null, new global::System.Type[] { typeof(global::ExpressiveSharp.Docs.PlaygroundModel.Webshop.Order), typeof(decimal) }, null), new global::System.Linq.Expressions.Expression[] { p_o, expr_4 });
            var expr_1 = global::System.Linq.Expressions.Expression.MakeBinary(global::System.Linq.Expressions.ExpressionType.Add, expr_2, expr_3);
            var expr_0 = global::System.Linq.Expressions.Expression.MakeBinary(global::System.Linq.Expressions.ExpressionType.GreaterThan, expr_1, p_threshold);
            return global::System.Linq.Expressions.Expression.Lambda<global::System.Func<global::ExpressiveSharp.Docs.PlaygroundModel.Webshop.Order, decimal, bool>>(expr_0, p_o, p_threshold);
        }
    }
}


// === ExpressiveSharp_Docs_Playground_Snippet_OrderExt.Attributes.g.cs ===
// <auto-generated/>

namespace ExpressiveSharp.Generated
{
    [global::System.ComponentModel.EditorBrowsable(global::System.ComponentModel.EditorBrowsableState.Never)]
    static partial class ExpressiveSharp_Docs_Playground_Snippet_OrderExt { }
}


// === ExpressionRegistry.g.cs ===
// <auto-generated/>
#nullable disable

using System;
using System.Collections.Generic;
using System.Linq.Expressions;
using System.Reflection;

namespace ExpressiveSharp.Generated
{
    [global::System.ComponentModel.EditorBrowsable(global::System.ComponentModel.EditorBrowsableState.Never)]
    internal static class ExpressionRegistry
    {
        private static Dictionary<nint, LambdaExpression> Build()
        {
            const BindingFlags allFlags = BindingFlags.Public | BindingFlags.NonPublic | BindingFlags.Instance | BindingFlags.Static;
            var map = new Dictionary<nint, LambdaExpression>();
            
            Register(map, typeof(global::ExpressiveSharp.Docs.Playground.Snippet.OrderExt).GetMethod("Subtotal", allFlags, null, new global::System.Type[] { typeof(global::ExpressiveSharp.Docs.PlaygroundModel.Webshop.Order) }, null), "ExpressiveSharp.Generated.ExpressiveSharp_Docs_Playground_Snippet_OrderExt", "Subtotal_P0_ExpressiveSharp_Docs_PlaygroundModel_Webshop_Order_Expression");
            Register(map, typeof(global::ExpressiveSharp.Docs.Playground.Snippet.OrderExt).GetMethod("Tax", allFlags, null, new global::System.Type[] { typeof(global::ExpressiveSharp.Docs.PlaygroundModel.Webshop.Order), typeof(decimal) }, null), "ExpressiveSharp.Generated.ExpressiveSharp_Docs_Playground_Snippet_OrderExt", "Tax_P0_ExpressiveSharp_Docs_PlaygroundModel_Webshop_Order_P1_decimal_Expression");
            Register(map, typeof(global::ExpressiveSharp.Docs.Playground.Snippet.OrderExt).GetMethod("ExceedsThreshold", allFlags, null, new global::System.Type[] { typeof(global::ExpressiveSharp.Docs.PlaygroundModel.Webshop.Order), typeof(decimal) }, null), "ExpressiveSharp.Generated.ExpressiveSharp_Docs_Playground_Snippet_OrderExt", "ExceedsThreshold_P0_ExpressiveSharp_Docs_PlaygroundModel_Webshop_Order_P1_decimal_Expression");
            
            return map;
        }
        
        private static volatile Dictionary<nint, LambdaExpression> _map = Build();
        
        internal static void ResetMap() => _map = Build();
        
        public static LambdaExpression TryGet(MemberInfo member)
        {
            var handle = member switch
            {
                MethodInfo m      => (nint?)m.MethodHandle.Value,
                PropertyInfo p    => p.GetMethod?.MethodHandle.Value,
                ConstructorInfo c => (nint?)c.MethodHandle.Value,
                _                 => null
            };
            
            return handle.HasValue && _map.TryGetValue(handle.Value, out var expr) ? expr : null;
        }
        
        private static void Register(Dictionary<nint, LambdaExpression> map, MethodBase m, string exprClass, string exprMethodName)
        {
            if (m is null) return;
            var exprType = m.DeclaringType?.Assembly.GetType(exprClass) ?? typeof(ExpressionRegistry).Assembly.GetType(exprClass);
            var exprMethod = exprType?.GetMethod(exprMethodName, BindingFlags.Static | BindingFlags.NonPublic);
            if (exprMethod is null) return;
            var expr = (LambdaExpression)exprMethod.Invoke(null, null)!;
            
            // Apply declared transformers from the generated class (if any)
            const string expressionSuffix = "_Expression";
            if (exprMethodName.EndsWith(expressionSuffix, StringComparison.Ordinal))
            {
                var transformersSuffix = exprMethodName.Substring(0, exprMethodName.Length - expressionSuffix.Length) + "_Transformers";
                var transformersMethod = exprType.GetMethod(transformersSuffix, BindingFlags.Static | BindingFlags.NonPublic);
                if (transformersMethod?.Invoke(null, null) is global::ExpressiveSharp.IExpressionTreeTransformer[] transformers)
                {
                    Expression transformed = expr;
                    foreach (var t in transformers) transformed = t.Transform(transformed);
                    if (transformed is LambdaExpression lambdaResult) expr = lambdaResult;
                }
            }
            
            map[m.MethodHandle.Value] = expr;
        }
    }
}


// === PolyfillInterceptors_b1293e61.g.cs ===
// <auto-generated/>
#nullable disable

namespace ExpressiveSharp.Generated.Interceptors
{
    internal static partial class PolyfillInterceptors
    {
        [global::System.Runtime.CompilerServices.InterceptsLocationAttribute(1, "fQ5GOYs2G+K1gMv8PyxsLaQBAABfX1NuaXBwZXQuY3M=")]
        internal static global::ExpressiveSharp.IExpressiveQueryable<int> __Polyfill_Select_3e61_14_58(
            this global::ExpressiveSharp.IExpressiveQueryable<global::ExpressiveSharp.Docs.PlaygroundModel.Webshop.Order> source,
            global::System.Func<global::ExpressiveSharp.Docs.PlaygroundModel.Webshop.Order, int> __func)
        {
            // Source: o => o.Id
            var i3e6114c58_p_o = global::System.Linq.Expressions.Expression.Parameter(typeof(global::ExpressiveSharp.Docs.PlaygroundModel.Webshop.Order), "o");
            var i3e6114c58_expr_0 = global::System.Linq.Expressions.Expression.Property(i3e6114c58_p_o, typeof(global::ExpressiveSharp.Docs.PlaygroundModel.Webshop.Order).GetProperty("Id", global::System.Reflection.BindingFlags.Public | global::System.Reflection.BindingFlags.NonPublic | global::System.Reflection.BindingFlags.Instance)); // o.Id
            var __lambda = global::System.Linq.Expressions.Expression.Lambda<global::System.Func<global::ExpressiveSharp.Docs.PlaygroundModel.Webshop.Order, int>>(i3e6114c58_expr_0, i3e6114c58_p_o);
            return global::ExpressiveSharp.ExpressiveQueryableExtensions.AsExpressive(
                global::System.Linq.Queryable.Select(
                    (global::System.Linq.IQueryable<global::ExpressiveSharp.Docs.PlaygroundModel.Webshop.Order>)source,
                    __lambda));
        }
        [global::System.Runtime.CompilerServices.InterceptsLocationAttribute(1, "fQ5GOYs2G+K1gMv8PyxsLX8BAABfX1NuaXBwZXQuY3M=")]
        internal static global::ExpressiveSharp.IExpressiveQueryable<global::ExpressiveSharp.Docs.PlaygroundModel.Webshop.Order> __Polyfill_Where_3e61_14_21(
            this global::ExpressiveSharp.IExpressiveQueryable<global::ExpressiveSharp.Docs.PlaygroundModel.Webshop.Order> source,
            global::System.Func<global::ExpressiveSharp.Docs.PlaygroundModel.Webshop.Order, bool> __func)
        {
            // Source: o => o.ExceedsThreshold(500m)
            var i3e6114c21_p_o = global::System.Linq.Expressions.Expression.Parameter(typeof(global::ExpressiveSharp.Docs.PlaygroundModel.Webshop.Order), "o");
            var i3e6114c21_expr_1 = global::System.Linq.Expressions.Expression.Constant(500m, typeof(decimal)); // 500m
            var i3e6114c21_expr_0 = global::System.Linq.Expressions.Expression.Call(typeof(global::ExpressiveSharp.Docs.Playground.Snippet.OrderExt).GetMethod("ExceedsThreshold", global::System.Reflection.BindingFlags.Public | global::System.Reflection.BindingFlags.NonPublic | global::System.Reflection.BindingFlags.Static, null, new global::System.Type[] { typeof(global::ExpressiveSharp.Docs.PlaygroundModel.Webshop.Order), typeof(decimal) }, null), new global::System.Linq.Expressions.Expression[] { i3e6114c21_p_o, i3e6114c21_expr_1 });
            var __lambda = global::System.Linq.Expressions.Expression.Lambda<global::System.Func<global::ExpressiveSharp.Docs.PlaygroundModel.Webshop.Order, bool>>(i3e6114c21_expr_0, i3e6114c21_p_o);
            return global::ExpressiveSharp.ExpressiveQueryableExtensions.AsExpressive(
                global::System.Linq.Queryable.Where(
                    (global::System.Linq.IQueryable<global::ExpressiveSharp.Docs.PlaygroundModel.Webshop.Order>)source,
                    __lambda));
        }
    }
}

namespace System.Runtime.CompilerServices
{
    [global::System.AttributeUsage(global::System.AttributeTargets.Method, AllowMultiple = true)]
    file sealed class InterceptsLocationAttribute : global::System.Attribute
    {
        public InterceptsLocationAttribute(int version, string data) { }
    }
}

Open in Playground →

Block-Bodied Methods ​

Methods can use traditional block bodies when AllowBlockBody = true:

C#
db
    .Orders
    .Select(o => new { o.Id, Category = o.GetCategory() })

// Setup
public static class OrderExt
{
    [Expressive(AllowBlockBody = true)]
    public static string GetCategory(this Order o)
    {
        var totalQty = o.Items.Sum(i => i.Quantity);
        if (totalQty > 10) return "Bulk";
        return "Regular";
    }
}
SELECT "o"."Id", CASE
    WHEN (
        SELECT COALESCE(SUM("l"."Quantity"), 0)
        FROM "LineItems" AS "l"
        WHERE "o"."Id" = "l"."OrderId") > 10 THEN 'Bulk'
    ELSE 'Regular'
END AS "Category"
FROM "Orders" AS "o"
SELECT o."Id", CASE
    WHEN (
        SELECT COALESCE(sum(l."Quantity"), 0)::int
        FROM "LineItems" AS l
        WHERE o."Id" = l."OrderId") > 10 THEN 'Bulk'
    ELSE 'Regular'
END AS "Category"
FROM "Orders" AS o
SELECT [o].[Id], CASE
    WHEN (
        SELECT COALESCE(SUM([l].[Quantity]), 0)
        FROM [LineItems] AS [l]
        WHERE [o].[Id] = [l].[OrderId]) > 10 THEN N'Bulk'
    ELSE N'Regular'
END AS [Category]
FROM [Orders] AS [o]
playground.orders.Aggregate([
    {
         "$project" : {
             "_id" : "$_id",
            "Category" : {
                 "$cond" : {
                     "if" : {
                         "$gt" : [
                            { "$sum" : "$Items.Quantity" },
                            10
                        ] 
                    },
                    "then" : "Bulk",
                    "else" : "Regular" 
                } 
            } 
        } 
    }
])
// === ExpressiveSharp_Docs_Playground_Snippet_OrderExt.GetCategory_P0_ExpressiveSharp_Docs_PlaygroundModel_Webshop_Order.g.cs ===
// <auto-generated/>
#nullable disable

using System;
using System.Linq;
using System.Linq.Expressions;
using ExpressiveSharp;
using ExpressiveSharp.EntityFrameworkCore;
using ExpressiveSharp.Docs.PlaygroundModel.Webshop;
using ExpressiveSharp.Docs.Playground.Snippet;

namespace ExpressiveSharp.Generated
{
    static partial class ExpressiveSharp_Docs_Playground_Snippet_OrderExt 
    {
        // [Expressive(AllowBlockBody = true)]
        // public static string GetCategory(this Order o)
        // {
        //     var totalQty = o.Items.Sum(i => i.Quantity);
        //     if (totalQty > 10)
        //         return "Bulk";
        //     return "Regular";
        // }
        static global::System.Linq.Expressions.Expression<global::System.Func<global::ExpressiveSharp.Docs.PlaygroundModel.Webshop.Order, string>> GetCategory_P0_ExpressiveSharp_Docs_PlaygroundModel_Webshop_Order_Expression() 
        {
            var p_o = global::System.Linq.Expressions.Expression.Parameter(typeof(global::ExpressiveSharp.Docs.PlaygroundModel.Webshop.Order), "o");
            var expr_0 = global::System.Linq.Expressions.Expression.Variable(typeof(int), "totalQty"); // {         var totalQty = o.Items.Sum(i => i.Quantity);   ...
            var expr_2 = global::System.Linq.Expressions.Expression.Property(p_o, typeof(global::ExpressiveSharp.Docs.PlaygroundModel.Webshop.Order).GetProperty("Items", global::System.Reflection.BindingFlags.Public | global::System.Reflection.BindingFlags.NonPublic | global::System.Reflection.BindingFlags.Instance)); // o.Items
            var p_i_3 = global::System.Linq.Expressions.Expression.Parameter(typeof(global::ExpressiveSharp.Docs.PlaygroundModel.Webshop.LineItem), "i"); // i => i.Quantity
            var expr_4 = global::System.Linq.Expressions.Expression.Property(p_i_3, typeof(global::ExpressiveSharp.Docs.PlaygroundModel.Webshop.LineItem).GetProperty("Quantity", global::System.Reflection.BindingFlags.Public | global::System.Reflection.BindingFlags.NonPublic | global::System.Reflection.BindingFlags.Instance)); // i.Quantity
            var expr_5 = global::System.Linq.Expressions.Expression.Lambda<global::System.Func<global::ExpressiveSharp.Docs.PlaygroundModel.Webshop.LineItem, int>>(expr_4, p_i_3);
            var expr_1 = global::System.Linq.Expressions.Expression.Call(global::System.Linq.Enumerable.First(global::System.Linq.Enumerable.Where(typeof(global::System.Linq.Enumerable).GetMethods(global::System.Reflection.BindingFlags.Public | global::System.Reflection.BindingFlags.NonPublic | global::System.Reflection.BindingFlags.Static), m => m.Name == "Sum" && m.IsGenericMethodDefinition && m.GetGenericArguments().Length == 1 && m.GetParameters().Length == 2 && m.GetParameters()[0].ParameterType.IsGenericType && !m.GetParameters()[0].ParameterType.IsGenericParameter && m.GetParameters()[1].ParameterType.IsGenericType && !m.GetParameters()[1].ParameterType.IsGenericParameter && m.GetParameters()[1].ParameterType.GetGenericArguments()[1] == typeof(int))).MakeGenericMethod(typeof(global::ExpressiveSharp.Docs.PlaygroundModel.Webshop.LineItem)), new global::System.Linq.Expressions.Expression[] { expr_2, expr_5 });
            var expr_6 = global::System.Linq.Expressions.Expression.Assign(expr_0, expr_1);
            var expr_9 = global::System.Linq.Expressions.Expression.Constant(10, typeof(int)); // 10
            var expr_8 = global::System.Linq.Expressions.Expression.MakeBinary(global::System.Linq.Expressions.ExpressionType.GreaterThan, expr_0, expr_9);
            var expr_10 = global::System.Linq.Expressions.Expression.Constant("Bulk", typeof(string)); // "Bulk"
            var expr_11 = global::System.Linq.Expressions.Expression.Constant("Regular", typeof(string)); // "Regular"
            var expr_7 = global::System.Linq.Expressions.Expression.Condition(expr_8, expr_10, expr_11, typeof(string));
            var expr_12 = global::System.Linq.Expressions.Expression.Block(new global::System.Linq.Expressions.ParameterExpression[] { expr_0 }, new global::System.Linq.Expressions.Expression[] { expr_6, expr_7 });
            return global::System.Linq.Expressions.Expression.Lambda<global::System.Func<global::ExpressiveSharp.Docs.PlaygroundModel.Webshop.Order, string>>(expr_12, p_o);
        }
    }
}


// === ExpressiveSharp_Docs_Playground_Snippet_OrderExt.Attributes.g.cs ===
// <auto-generated/>

namespace ExpressiveSharp.Generated
{
    [global::System.ComponentModel.EditorBrowsable(global::System.ComponentModel.EditorBrowsableState.Never)]
    static partial class ExpressiveSharp_Docs_Playground_Snippet_OrderExt { }
}


// === ExpressionRegistry.g.cs ===
// <auto-generated/>
#nullable disable

using System;
using System.Collections.Generic;
using System.Linq.Expressions;
using System.Reflection;

namespace ExpressiveSharp.Generated
{
    [global::System.ComponentModel.EditorBrowsable(global::System.ComponentModel.EditorBrowsableState.Never)]
    internal static class ExpressionRegistry
    {
        private static Dictionary<nint, LambdaExpression> Build()
        {
            const BindingFlags allFlags = BindingFlags.Public | BindingFlags.NonPublic | BindingFlags.Instance | BindingFlags.Static;
            var map = new Dictionary<nint, LambdaExpression>();
            
            Register(map, typeof(global::ExpressiveSharp.Docs.Playground.Snippet.OrderExt).GetMethod("GetCategory", allFlags, null, new global::System.Type[] { typeof(global::ExpressiveSharp.Docs.PlaygroundModel.Webshop.Order) }, null), "ExpressiveSharp.Generated.ExpressiveSharp_Docs_Playground_Snippet_OrderExt", "GetCategory_P0_ExpressiveSharp_Docs_PlaygroundModel_Webshop_Order_Expression");
            
            return map;
        }
        
        private static volatile Dictionary<nint, LambdaExpression> _map = Build();
        
        internal static void ResetMap() => _map = Build();
        
        public static LambdaExpression TryGet(MemberInfo member)
        {
            var handle = member switch
            {
                MethodInfo m      => (nint?)m.MethodHandle.Value,
                PropertyInfo p    => p.GetMethod?.MethodHandle.Value,
                ConstructorInfo c => (nint?)c.MethodHandle.Value,
                _                 => null
            };
            
            return handle.HasValue && _map.TryGetValue(handle.Value, out var expr) ? expr : null;
        }
        
        private static void Register(Dictionary<nint, LambdaExpression> map, MethodBase m, string exprClass, string exprMethodName)
        {
            if (m is null) return;
            var exprType = m.DeclaringType?.Assembly.GetType(exprClass) ?? typeof(ExpressionRegistry).Assembly.GetType(exprClass);
            var exprMethod = exprType?.GetMethod(exprMethodName, BindingFlags.Static | BindingFlags.NonPublic);
            if (exprMethod is null) return;
            var expr = (LambdaExpression)exprMethod.Invoke(null, null)!;
            
            // Apply declared transformers from the generated class (if any)
            const string expressionSuffix = "_Expression";
            if (exprMethodName.EndsWith(expressionSuffix, StringComparison.Ordinal))
            {
                var transformersSuffix = exprMethodName.Substring(0, exprMethodName.Length - expressionSuffix.Length) + "_Transformers";
                var transformersMethod = exprType.GetMethod(transformersSuffix, BindingFlags.Static | BindingFlags.NonPublic);
                if (transformersMethod?.Invoke(null, null) is global::ExpressiveSharp.IExpressionTreeTransformer[] transformers)
                {
                    Expression transformed = expr;
                    foreach (var t in transformers) transformed = t.Transform(transformed);
                    if (transformed is LambdaExpression lambdaResult) expr = lambdaResult;
                }
            }
            
            map[m.MethodHandle.Value] = expr;
        }
    }
}


// === PolyfillInterceptors_b1293e61.g.cs ===
// <auto-generated/>
#nullable disable

namespace ExpressiveSharp.Generated.Interceptors
{
    internal static partial class PolyfillInterceptors
    {
        [global::System.Runtime.CompilerServices.InterceptsLocationAttribute(1, "SwKrZvxfDBT8/peXXYeoYH8BAABfX1NuaXBwZXQuY3M=")]
        internal static global::ExpressiveSharp.IExpressiveQueryable<T1> __Polyfill_Select_3e61_14_21<T0, T1>(
            this global::ExpressiveSharp.IExpressiveQueryable<T0> source,
            global::System.Func<T0, T1> __func)
        {
            // Source: o => new { o.Id, Category = o.GetCategory() }
            var i3e6114c21_p_o = global::System.Linq.Expressions.Expression.Parameter(typeof(T0), "o");
            var i3e6114c21_expr_1 = global::System.Linq.Expressions.Expression.Property(i3e6114c21_p_o, typeof(T0).GetProperty("Id", global::System.Reflection.BindingFlags.Public | global::System.Reflection.BindingFlags.NonPublic | global::System.Reflection.BindingFlags.Instance)); // o.Id
            var i3e6114c21_expr_2 = global::System.Linq.Expressions.Expression.Call(typeof(global::ExpressiveSharp.Docs.Playground.Snippet.OrderExt).GetMethod("GetCategory", global::System.Reflection.BindingFlags.Public | global::System.Reflection.BindingFlags.NonPublic | global::System.Reflection.BindingFlags.Static, null, new global::System.Type[] { typeof(T0) }, null), new global::System.Linq.Expressions.Expression[] { i3e6114c21_p_o }); // o.GetCategory()
            var i3e6114c21_expr_3 = typeof(T1).GetConstructors()[0];
            var i3e6114c21_expr_0 = global::System.Linq.Expressions.Expression.New(i3e6114c21_expr_3, new global::System.Linq.Expressions.Expression[] { i3e6114c21_expr_1, i3e6114c21_expr_2 }, new global::System.Reflection.MemberInfo[] { typeof(T1).GetProperty("Id"), typeof(T1).GetProperty("Category") });
            var __lambda = global::System.Linq.Expressions.Expression.Lambda<global::System.Func<T0, T1>>(i3e6114c21_expr_0, i3e6114c21_p_o);
            return (global::ExpressiveSharp.IExpressiveQueryable<T1>)(object)
                global::ExpressiveSharp.ExpressiveQueryableExtensions.AsExpressive(
                    global::System.Linq.Queryable.Select(
                        (global::System.Linq.IQueryable<T0>)(object)source,
                        __lambda));
        }
    }
}

namespace System.Runtime.CompilerServices
{
    [global::System.AttributeUsage(global::System.AttributeTargets.Method, AllowMultiple = true)]
    file sealed class InterceptsLocationAttribute : global::System.Attribute
    {
        public InterceptsLocationAttribute(int version, string data) { }
    }
}

Open in Playground →

Block bodies support:

  • Local variable declarations (inlined at each usage point)
  • if/else chains (converted to ternary / CASE expressions)
  • switch statements
  • foreach loops (converted to LINQ method calls)
  • for loops (array/list iteration)

WARNING

Not all constructs are supported in block bodies. Unsupported statements (while/do-while, try/catch, async/await) trigger diagnostic EXP0006. Side-effect constructs (assignments, ++/--) trigger diagnostic EXP0005.

You can also enable block bodies globally for a project:

xml
<PropertyGroup>
    <Expressive_AllowBlockBody>true</Expressive_AllowBlockBody>
</PropertyGroup>

Static Methods ​

[Expressive] can be applied to static methods as well. Here, CalculateLinePrice is a pure static helper with no receiver:

C#
db
    .LineItems
    .Select(i => new
    {
        i.Id,
        Discounted = OrderHelpers.CalculateLinePrice(i.UnitPrice, i.Quantity),
    })

// Setup
public static class OrderHelpers
{
    [Expressive]
    public static decimal CalculateLinePrice(decimal price, int quantity) =>
        price * quantity > 1000m ? price * quantity * 0.9m : price * quantity;
}
SELECT "l"."Id", CASE
    WHEN ef_compare(ef_multiply("l"."UnitPrice", CAST("l"."Quantity" AS TEXT)), '1000.0') > 0 THEN ef_multiply(ef_multiply("l"."UnitPrice", CAST("l"."Quantity" AS TEXT)), '0.9')
    ELSE ef_multiply("l"."UnitPrice", CAST("l"."Quantity" AS TEXT))
END AS "Discounted"
FROM "LineItems" AS "l"
SELECT l."Id", CASE
    WHEN l."UnitPrice" * l."Quantity"::numeric(18,2) > 1000.0 THEN l."UnitPrice" * l."Quantity"::numeric(18,2) * 0.9
    ELSE l."UnitPrice" * l."Quantity"::numeric(18,2)
END AS "Discounted"
FROM "LineItems" AS l
SELECT [l].[Id], CASE
    WHEN [l].[UnitPrice] * CAST([l].[Quantity] AS decimal(18,2)) > 1000.0 THEN [l].[UnitPrice] * CAST([l].[Quantity] AS decimal(18,2)) * 0.9
    ELSE [l].[UnitPrice] * CAST([l].[Quantity] AS decimal(18,2))
END AS [Discounted]
FROM [LineItems] AS [l]
playground.line_items.Aggregate([
    {
         "$project" : {
             "_id" : "$_id",
            "Discounted" : {
                 "$cond" : {
                     "if" : {
                         "$gt" : [
                            {
                                 "$multiply" : ["$UnitPrice", "$Quantity"] 
                            },
                            { "$numberDecimal" : "1000" }
                        ] 
                    },
                    "then" : {
                         "$multiply" : [
                            "$UnitPrice",
                            "$Quantity",
                            { "$numberDecimal" : "0.9" }
                        ] 
                    },
                    "else" : {
                         "$multiply" : ["$UnitPrice", "$Quantity"] 
                    } 
                } 
            } 
        } 
    }
])
// === ExpressiveSharp_Docs_Playground_Snippet_OrderHelpers.CalculateLinePrice_P0_decimal_P1_int.g.cs ===
// <auto-generated/>
#nullable disable

using System;
using System.Linq;
using System.Linq.Expressions;
using ExpressiveSharp;
using ExpressiveSharp.EntityFrameworkCore;
using ExpressiveSharp.Docs.PlaygroundModel.Webshop;
using ExpressiveSharp.Docs.Playground.Snippet;

namespace ExpressiveSharp.Generated
{
    static partial class ExpressiveSharp_Docs_Playground_Snippet_OrderHelpers 
    {
        // [Expressive]
        // public static decimal CalculateLinePrice(decimal price, int quantity) => price * quantity > 1000m ? price * quantity * 0.9m : price * quantity;
        static global::System.Linq.Expressions.Expression<global::System.Func<decimal, int, decimal>> CalculateLinePrice_P0_decimal_P1_int_Expression() 
        {
            var p_price = global::System.Linq.Expressions.Expression.Parameter(typeof(decimal), "price");
            var p_quantity = global::System.Linq.Expressions.Expression.Parameter(typeof(int), "quantity");
            var expr_3 = global::System.Linq.Expressions.Expression.Convert(p_quantity, typeof(decimal)); // quantity
            var expr_2 = global::System.Linq.Expressions.Expression.MakeBinary(global::System.Linq.Expressions.ExpressionType.Multiply, p_price, expr_3);
            var expr_4 = global::System.Linq.Expressions.Expression.Constant(1000m, typeof(decimal)); // 1000m
            var expr_1 = global::System.Linq.Expressions.Expression.MakeBinary(global::System.Linq.Expressions.ExpressionType.GreaterThan, expr_2, expr_4);
            var expr_7 = global::System.Linq.Expressions.Expression.Convert(p_quantity, typeof(decimal)); // quantity
            var expr_6 = global::System.Linq.Expressions.Expression.MakeBinary(global::System.Linq.Expressions.ExpressionType.Multiply, p_price, expr_7);
            var expr_8 = global::System.Linq.Expressions.Expression.Constant(0.9m, typeof(decimal)); // 0.9m
            var expr_5 = global::System.Linq.Expressions.Expression.MakeBinary(global::System.Linq.Expressions.ExpressionType.Multiply, expr_6, expr_8);
            var expr_10 = global::System.Linq.Expressions.Expression.Convert(p_quantity, typeof(decimal)); // quantity
            var expr_9 = global::System.Linq.Expressions.Expression.MakeBinary(global::System.Linq.Expressions.ExpressionType.Multiply, p_price, expr_10);
            var expr_0 = global::System.Linq.Expressions.Expression.Condition(expr_1, expr_5, expr_9, typeof(decimal));
            return global::System.Linq.Expressions.Expression.Lambda<global::System.Func<decimal, int, decimal>>(expr_0, p_price, p_quantity);
        }
    }
}


// === ExpressiveSharp_Docs_Playground_Snippet_OrderHelpers.Attributes.g.cs ===
// <auto-generated/>

namespace ExpressiveSharp.Generated
{
    [global::System.ComponentModel.EditorBrowsable(global::System.ComponentModel.EditorBrowsableState.Never)]
    static partial class ExpressiveSharp_Docs_Playground_Snippet_OrderHelpers { }
}


// === ExpressionRegistry.g.cs ===
// <auto-generated/>
#nullable disable

using System;
using System.Collections.Generic;
using System.Linq.Expressions;
using System.Reflection;

namespace ExpressiveSharp.Generated
{
    [global::System.ComponentModel.EditorBrowsable(global::System.ComponentModel.EditorBrowsableState.Never)]
    internal static class ExpressionRegistry
    {
        private static Dictionary<nint, LambdaExpression> Build()
        {
            const BindingFlags allFlags = BindingFlags.Public | BindingFlags.NonPublic | BindingFlags.Instance | BindingFlags.Static;
            var map = new Dictionary<nint, LambdaExpression>();
            
            Register(map, typeof(global::ExpressiveSharp.Docs.Playground.Snippet.OrderHelpers).GetMethod("CalculateLinePrice", allFlags, null, new global::System.Type[] { typeof(decimal), typeof(int) }, null), "ExpressiveSharp.Generated.ExpressiveSharp_Docs_Playground_Snippet_OrderHelpers", "CalculateLinePrice_P0_decimal_P1_int_Expression");
            
            return map;
        }
        
        private static volatile Dictionary<nint, LambdaExpression> _map = Build();
        
        internal static void ResetMap() => _map = Build();
        
        public static LambdaExpression TryGet(MemberInfo member)
        {
            var handle = member switch
            {
                MethodInfo m      => (nint?)m.MethodHandle.Value,
                PropertyInfo p    => p.GetMethod?.MethodHandle.Value,
                ConstructorInfo c => (nint?)c.MethodHandle.Value,
                _                 => null
            };
            
            return handle.HasValue && _map.TryGetValue(handle.Value, out var expr) ? expr : null;
        }
        
        private static void Register(Dictionary<nint, LambdaExpression> map, MethodBase m, string exprClass, string exprMethodName)
        {
            if (m is null) return;
            var exprType = m.DeclaringType?.Assembly.GetType(exprClass) ?? typeof(ExpressionRegistry).Assembly.GetType(exprClass);
            var exprMethod = exprType?.GetMethod(exprMethodName, BindingFlags.Static | BindingFlags.NonPublic);
            if (exprMethod is null) return;
            var expr = (LambdaExpression)exprMethod.Invoke(null, null)!;
            
            // Apply declared transformers from the generated class (if any)
            const string expressionSuffix = "_Expression";
            if (exprMethodName.EndsWith(expressionSuffix, StringComparison.Ordinal))
            {
                var transformersSuffix = exprMethodName.Substring(0, exprMethodName.Length - expressionSuffix.Length) + "_Transformers";
                var transformersMethod = exprType.GetMethod(transformersSuffix, BindingFlags.Static | BindingFlags.NonPublic);
                if (transformersMethod?.Invoke(null, null) is global::ExpressiveSharp.IExpressionTreeTransformer[] transformers)
                {
                    Expression transformed = expr;
                    foreach (var t in transformers) transformed = t.Transform(transformed);
                    if (transformed is LambdaExpression lambdaResult) expr = lambdaResult;
                }
            }
            
            map[m.MethodHandle.Value] = expr;
        }
    }
}


// === PolyfillInterceptors_b1293e61.g.cs ===
// <auto-generated/>
#nullable disable

namespace ExpressiveSharp.Generated.Interceptors
{
    internal static partial class PolyfillInterceptors
    {
        [global::System.Runtime.CompilerServices.InterceptsLocationAttribute(1, "WUheD7nDTvhZrbxIObDVH4IBAABfX1NuaXBwZXQuY3M=")]
        internal static global::ExpressiveSharp.IExpressiveQueryable<T1> __Polyfill_Select_3e61_14_24<T0, T1>(
            this global::ExpressiveSharp.IExpressiveQueryable<T0> source,
            global::System.Func<T0, T1> __func)
        {
            // Source: i => new { i.Id, Discounted = OrderHelpers.CalculateLinePrice(i.UnitPrice, i.Quantity), }
            var i3e6114c24_p_i = global::System.Linq.Expressions.Expression.Parameter(typeof(T0), "i");
            var i3e6114c24_expr_1 = global::System.Linq.Expressions.Expression.Property(i3e6114c24_p_i, typeof(T0).GetProperty("Id", global::System.Reflection.BindingFlags.Public | global::System.Reflection.BindingFlags.NonPublic | global::System.Reflection.BindingFlags.Instance)); // i.Id
            var i3e6114c24_expr_3 = global::System.Linq.Expressions.Expression.Property(i3e6114c24_p_i, typeof(T0).GetProperty("UnitPrice", global::System.Reflection.BindingFlags.Public | global::System.Reflection.BindingFlags.NonPublic | global::System.Reflection.BindingFlags.Instance)); // i.UnitPrice
            var i3e6114c24_expr_4 = global::System.Linq.Expressions.Expression.Property(i3e6114c24_p_i, typeof(T0).GetProperty("Quantity", global::System.Reflection.BindingFlags.Public | global::System.Reflection.BindingFlags.NonPublic | global::System.Reflection.BindingFlags.Instance)); // i.Quantity
            var i3e6114c24_expr_2 = global::System.Linq.Expressions.Expression.Call(typeof(global::ExpressiveSharp.Docs.Playground.Snippet.OrderHelpers).GetMethod("CalculateLinePrice", global::System.Reflection.BindingFlags.Public | global::System.Reflection.BindingFlags.NonPublic | global::System.Reflection.BindingFlags.Static, null, new global::System.Type[] { typeof(decimal), typeof(int) }, null), new global::System.Linq.Expressions.Expression[] { i3e6114c24_expr_3, i3e6114c24_expr_4 });
            var i3e6114c24_expr_5 = typeof(T1).GetConstructors()[0];
            var i3e6114c24_expr_0 = global::System.Linq.Expressions.Expression.New(i3e6114c24_expr_5, new global::System.Linq.Expressions.Expression[] { i3e6114c24_expr_1, i3e6114c24_expr_2 }, new global::System.Reflection.MemberInfo[] { typeof(T1).GetProperty("Id"), typeof(T1).GetProperty("Discounted") });
            var __lambda = global::System.Linq.Expressions.Expression.Lambda<global::System.Func<T0, T1>>(i3e6114c24_expr_0, i3e6114c24_p_i);
            return (global::ExpressiveSharp.IExpressiveQueryable<T1>)(object)
                global::ExpressiveSharp.ExpressiveQueryableExtensions.AsExpressive(
                    global::System.Linq.Queryable.Select(
                        (global::System.Linq.IQueryable<T0>)(object)source,
                        __lambda));
        }
    }
}

namespace System.Runtime.CompilerServices
{
    [global::System.AttributeUsage(global::System.AttributeTargets.Method, AllowMultiple = true)]
    file sealed class InterceptsLocationAttribute : global::System.Attribute
    {
        public InterceptsLocationAttribute(int version, string data) { }
    }
}

Open in Playground →

Important Rules ​

  • Methods must be expression-bodied (=>) unless AllowBlockBody = true.
  • If a method has no body, the generator reports diagnostic EXP0001.
  • If a method uses a block body without opting in, the generator reports diagnostic EXP0004.
  • Parameter types must be supported by your LINQ provider (primitive types, enums, and other provider-translatable types).

Next Steps ​

Released under the MIT License.

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