Extension Members

ExpressiveSharp supports [Expressive] on both traditional extension methods (any .NET version) and C# 14 extension members (.NET 10+). This lets you define query logic outside of your entity classes -- useful for keeping entities clean, applying logic to types you don't own, or grouping related query helpers.

Extension Methods

Add [Expressive] to any extension method in a static class and use it inside your queries:

C#

db
    .Orders
    .Where(o => o.IsHighValue(500m))
    .Select(o => new { o.Id, Email = o.SafeCustomerEmail() })

// Setup
public static class OrderExtensions
{
    [Expressive]
    public static bool IsHighValue(this Order order, decimal threshold)
        => order.Items.Sum(i => i.UnitPrice * i.Quantity) > threshold;

    [Expressive]
    public static string? SafeCustomerEmail(this Order order)
        => order.Customer != null ? order.Customer.Email : null;
}

SELECT "o"."Id", "c"."Email"
FROM "Orders" AS "o"
INNER JOIN "Customers" AS "c" ON "o"."CustomerId" = "c"."Id"
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", c."Email"
FROM "Orders" AS o
INNER JOIN "Customers" AS c ON o."CustomerId" = c."Id"
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], [c].[Email]
FROM [Orders] AS [o]
INNER JOIN [Customers] AS [c] ON [o].[CustomerId] = [c].[Id]
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" : "$_id",
            "Email" : {
                 "$cond" : {
                     "if" : {
                         "$ne" : ["$Customer", null] 
                    },
                    "then" : "$Customer.Email",
                    "else" : null 
                } 
            } 
        } 
    }
])

// === ExpressiveSharp_Docs_Playground_Snippet_OrderExtensions.IsHighValue_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_OrderExtensions 
    {
        // [Expressive]
        // public static bool IsHighValue(this Order order, decimal threshold) => order.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>> IsHighValue_P0_ExpressiveSharp_Docs_PlaygroundModel_Webshop_Order_P1_decimal_Expression() 
        {
            var p_order = global::System.Linq.Expressions.Expression.Parameter(typeof(global::ExpressiveSharp.Docs.PlaygroundModel.Webshop.Order), "order");
            var p_threshold = global::System.Linq.Expressions.Expression.Parameter(typeof(decimal), "threshold");
            var expr_2 = global::System.Linq.Expressions.Expression.Property(p_order, typeof(global::ExpressiveSharp.Docs.PlaygroundModel.Webshop.Order).GetProperty("Items", global::System.Reflection.BindingFlags.Public | global::System.Reflection.BindingFlags.NonPublic | global::System.Reflection.BindingFlags.Instance)); // order.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_order, p_threshold);
        }
    }
}


// === ExpressiveSharp_Docs_Playground_Snippet_OrderExtensions.SafeCustomerEmail_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_OrderExtensions 
    {
        // [Expressive]
        // public static string? SafeCustomerEmail(this Order order) => order.Customer != null ? order.Customer.Email : null;
        static global::System.Linq.Expressions.Expression<global::System.Func<global::ExpressiveSharp.Docs.PlaygroundModel.Webshop.Order, string>> SafeCustomerEmail_P0_ExpressiveSharp_Docs_PlaygroundModel_Webshop_Order_Expression() 
        {
            var p_order = global::System.Linq.Expressions.Expression.Parameter(typeof(global::ExpressiveSharp.Docs.PlaygroundModel.Webshop.Order), "order");
            var expr_3 = global::System.Linq.Expressions.Expression.Property(p_order, typeof(global::ExpressiveSharp.Docs.PlaygroundModel.Webshop.Order).GetProperty("Customer", global::System.Reflection.BindingFlags.Public | global::System.Reflection.BindingFlags.NonPublic | global::System.Reflection.BindingFlags.Instance)); // order.Customer
            var expr_2 = global::System.Linq.Expressions.Expression.Convert(expr_3, typeof(object));
            var expr_5 = global::System.Linq.Expressions.Expression.Constant(null, typeof(object)); // null
            var expr_4 = global::System.Linq.Expressions.Expression.Convert(expr_5, typeof(object));
            var expr_1 = global::System.Linq.Expressions.Expression.MakeBinary(global::System.Linq.Expressions.ExpressionType.NotEqual, expr_2, expr_4);
            var expr_7 = global::System.Linq.Expressions.Expression.Property(p_order, typeof(global::ExpressiveSharp.Docs.PlaygroundModel.Webshop.Order).GetProperty("Customer", global::System.Reflection.BindingFlags.Public | global::System.Reflection.BindingFlags.NonPublic | global::System.Reflection.BindingFlags.Instance)); // order.Customer
            var expr_6 = global::System.Linq.Expressions.Expression.Property(expr_7, typeof(global::ExpressiveSharp.Docs.PlaygroundModel.Webshop.Customer).GetProperty("Email", global::System.Reflection.BindingFlags.Public | global::System.Reflection.BindingFlags.NonPublic | global::System.Reflection.BindingFlags.Instance));
            var expr_9 = global::System.Linq.Expressions.Expression.Constant(null, typeof(object)); // null
            var expr_8 = global::System.Linq.Expressions.Expression.Convert(expr_9, typeof(string));
            var expr_0 = global::System.Linq.Expressions.Expression.Condition(expr_1, expr_6, expr_8, typeof(string));
            return global::System.Linq.Expressions.Expression.Lambda<global::System.Func<global::ExpressiveSharp.Docs.PlaygroundModel.Webshop.Order, string>>(expr_0, p_order);
        }
    }
}


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

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


// === 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.OrderExtensions).GetMethod("IsHighValue", allFlags, null, new global::System.Type[] { typeof(global::ExpressiveSharp.Docs.PlaygroundModel.Webshop.Order), typeof(decimal) }, null), "ExpressiveSharp.Generated.ExpressiveSharp_Docs_Playground_Snippet_OrderExtensions", "IsHighValue_P0_ExpressiveSharp_Docs_PlaygroundModel_Webshop_Order_P1_decimal_Expression");
            Register(map, typeof(global::ExpressiveSharp.Docs.Playground.Snippet.OrderExtensions).GetMethod("SafeCustomerEmail", allFlags, null, new global::System.Type[] { typeof(global::ExpressiveSharp.Docs.PlaygroundModel.Webshop.Order) }, null), "ExpressiveSharp.Generated.ExpressiveSharp_Docs_Playground_Snippet_OrderExtensions", "SafeCustomerEmail_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, "o8iGD2IUSLg1e1pdxcKnqqkBAABfX1NuaXBwZXQuY3M=")]
        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, Email = o.SafeCustomerEmail() }
            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_2 = global::System.Linq.Expressions.Expression.Call(typeof(global::ExpressiveSharp.Docs.Playground.Snippet.OrderExtensions).GetMethod("SafeCustomerEmail", 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[] { i3e6116c5_p_o }); // o.SafeCustomerEmail()
            var i3e6116c5_expr_3 = typeof(T1).GetConstructors()[0];
            var i3e6116c5_expr_0 = global::System.Linq.Expressions.Expression.New(i3e6116c5_expr_3, new global::System.Linq.Expressions.Expression[] { i3e6116c5_expr_1, i3e6116c5_expr_2 }, new global::System.Reflection.MemberInfo[] { typeof(T1).GetProperty("Id"), typeof(T1).GetProperty("Email") });
            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, "o8iGD2IUSLg1e1pdxcKnqoQBAABfX1NuaXBwZXQuY3M=")]
        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.IsHighValue(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.OrderExtensions).GetMethod("IsHighValue", 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 →

db
    .Orders
    .Where(o => o.IsHighValue(500m))
    .Select(o => new { o.Id, Email = o.SafeCustomerEmail() })

// Setup
public static class OrderExtensions
{
    [Expressive]
    public static bool IsHighValue(this Order order, decimal threshold)
        => order.Items.Sum(i => i.UnitPrice * i.Quantity) > threshold;

    [Expressive]
    public static string? SafeCustomerEmail(this Order order)
        => order.Customer != null ? order.Customer.Email : null;
}

Generated SQL:

SELECT "o"."Id", "c"."Email"
FROM "Orders" AS "o"
INNER JOIN "Customers" AS "c" ON "o"."CustomerId" = "c"."Id"
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

The extension method body is inlined into the expression tree -- the provider sees the expanded arithmetic and member access, not a method call. The query tabs above show how each provider translates the result.

Extension Methods on Non-Entity Types

Extension methods work on any type, not just entities:

C#

db
    .Products
    .Where(p => p.Name.ContainsIgnoreCase("widget"))

// Setup
public static class StringExtensions
{
    [Expressive]
    public static bool ContainsIgnoreCase(this string source, string value)
        => source.ToLower().Contains(value.ToLower());
}

SELECT "p"."Id", "p"."Category", "p"."ListPrice", "p"."Name", "p"."StockQuantity"
FROM "Products" AS "p"
WHERE instr(lower("p"."Name"), 'widget') > 0

SELECT p."Id", p."Category", p."ListPrice", p."Name", p."StockQuantity"
FROM "Products" AS p
WHERE lower(p."Name") LIKE '%widget%'

SELECT [p].[Id], [p].[Category], [p].[ListPrice], [p].[Name], [p].[StockQuantity]
FROM [Products] AS [p]
WHERE LOWER([p].[Name]) LIKE N'%widget%'

playground.products.Aggregate([
    {
         "$match" : {
             "Name" : {
                 "$regularExpression" : { "pattern" : "widget", "options" : "is" } 
            } 
        } 
    }
])

// === ExpressiveSharp_Docs_Playground_Snippet_StringExtensions.ContainsIgnoreCase_P0_string_P1_string.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_StringExtensions 
    {
        // [Expressive]
        // public static bool ContainsIgnoreCase(this string source, string value) => source.ToLower().Contains(value.ToLower());
        static global::System.Linq.Expressions.Expression<global::System.Func<string, string, bool>> ContainsIgnoreCase_P0_string_P1_string_Expression() 
        {
            var p_source = global::System.Linq.Expressions.Expression.Parameter(typeof(string), "source");
            var p_value = global::System.Linq.Expressions.Expression.Parameter(typeof(string), "value");
            var expr_1 = global::System.Linq.Expressions.Expression.Call(p_value, typeof(string).GetMethod("ToLower", global::System.Reflection.BindingFlags.Public | global::System.Reflection.BindingFlags.NonPublic | global::System.Reflection.BindingFlags.Instance, null, new global::System.Type[] {  }, null), global::System.Array.Empty<global::System.Linq.Expressions.Expression>()); // value.ToLower()
            var expr_2 = global::System.Linq.Expressions.Expression.Call(p_source, typeof(string).GetMethod("ToLower", global::System.Reflection.BindingFlags.Public | global::System.Reflection.BindingFlags.NonPublic | global::System.Reflection.BindingFlags.Instance, null, new global::System.Type[] {  }, null), global::System.Array.Empty<global::System.Linq.Expressions.Expression>()); // source.ToLower()
            var expr_0 = global::System.Linq.Expressions.Expression.Call(expr_2, typeof(string).GetMethod("Contains", global::System.Reflection.BindingFlags.Public | global::System.Reflection.BindingFlags.NonPublic | global::System.Reflection.BindingFlags.Instance, null, new global::System.Type[] { typeof(string) }, null), new global::System.Linq.Expressions.Expression[] { expr_1 });
            return global::System.Linq.Expressions.Expression.Lambda<global::System.Func<string, string, bool>>(expr_0, p_source, p_value);
        }
    }
}


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

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


// === 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.StringExtensions).GetMethod("ContainsIgnoreCase", allFlags, null, new global::System.Type[] { typeof(string), typeof(string) }, null), "ExpressiveSharp.Generated.ExpressiveSharp_Docs_Playground_Snippet_StringExtensions", "ContainsIgnoreCase_P0_string_P1_string_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, "z7dqg/30Ght1qWL+6CDalYEBAABfX1NuaXBwZXQuY3M=")]
        internal static global::ExpressiveSharp.IExpressiveQueryable<global::ExpressiveSharp.Docs.PlaygroundModel.Webshop.Product> __Polyfill_Where_3e61_14_23(
            this global::ExpressiveSharp.IExpressiveQueryable<global::ExpressiveSharp.Docs.PlaygroundModel.Webshop.Product> source,
            global::System.Func<global::ExpressiveSharp.Docs.PlaygroundModel.Webshop.Product, bool> __func)
        {
            // Source: p => p.Name.ContainsIgnoreCase("widget")
            var i3e6114c23_p_p = global::System.Linq.Expressions.Expression.Parameter(typeof(global::ExpressiveSharp.Docs.PlaygroundModel.Webshop.Product), "p");
            var i3e6114c23_expr_1 = global::System.Linq.Expressions.Expression.Property(i3e6114c23_p_p, typeof(global::ExpressiveSharp.Docs.PlaygroundModel.Webshop.Product).GetProperty("Name", global::System.Reflection.BindingFlags.Public | global::System.Reflection.BindingFlags.NonPublic | global::System.Reflection.BindingFlags.Instance)); // p.Name
            var i3e6114c23_expr_2 = global::System.Linq.Expressions.Expression.Constant("widget", typeof(string)); // "widget"
            var i3e6114c23_expr_0 = global::System.Linq.Expressions.Expression.Call(typeof(global::ExpressiveSharp.Docs.Playground.Snippet.StringExtensions).GetMethod("ContainsIgnoreCase", global::System.Reflection.BindingFlags.Public | global::System.Reflection.BindingFlags.NonPublic | global::System.Reflection.BindingFlags.Static, null, new global::System.Type[] { typeof(string), typeof(string) }, null), new global::System.Linq.Expressions.Expression[] { i3e6114c23_expr_1, i3e6114c23_expr_2 });
            var __lambda = global::System.Linq.Expressions.Expression.Lambda<global::System.Func<global::ExpressiveSharp.Docs.PlaygroundModel.Webshop.Product, bool>>(i3e6114c23_expr_0, i3e6114c23_p_p);
            return global::ExpressiveSharp.ExpressiveQueryableExtensions.AsExpressive(
                global::System.Linq.Queryable.Where(
                    (global::System.Linq.IQueryable<global::ExpressiveSharp.Docs.PlaygroundModel.Webshop.Product>)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 →

db
    .Products
    .Where(p => p.Name.ContainsIgnoreCase("widget"))

// Setup
public static class StringExtensions
{
    [Expressive]
    public static bool ContainsIgnoreCase(this string source, string value)
        => source.ToLower().Contains(value.ToLower());
}

Generated SQL:

SELECT "p"."Id", "p"."Category", "p"."ListPrice", "p"."Name", "p"."StockQuantity"
FROM "Products" AS "p"
WHERE instr(lower("p"."Name"), 'widget') > 0

Primitive extensions compose the same way:

C#

db
    .LineItems
    .Select(i => new { i.Id, SquaredQty = i.Quantity.Squared() })

// Setup
public static class IntExtensions
{
    [Expressive]
    public static int Squared(this int i) => i * i;
}

SELECT "l"."Id", "l"."Quantity" * "l"."Quantity" AS "SquaredQty"
FROM "LineItems" AS "l"

SELECT l."Id", l."Quantity" * l."Quantity" AS "SquaredQty"
FROM "LineItems" AS l

SELECT [l].[Id], [l].[Quantity] * [l].[Quantity] AS [SquaredQty]
FROM [LineItems] AS [l]

playground.line_items.Aggregate([
    {
         "$project" : {
             "_id" : "$_id",
            "SquaredQty" : {
                 "$multiply" : ["$Quantity", "$Quantity"] 
            } 
        } 
    }
])

// === ExpressiveSharp_Docs_Playground_Snippet_IntExtensions.Squared_P0_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_IntExtensions 
    {
        // [Expressive]
        // public static int Squared(this int i) => i * i;
        static global::System.Linq.Expressions.Expression<global::System.Func<int, int>> Squared_P0_int_Expression() 
        {
            var p_i = global::System.Linq.Expressions.Expression.Parameter(typeof(int), "i");
            var expr_0 = global::System.Linq.Expressions.Expression.MakeBinary(global::System.Linq.Expressions.ExpressionType.Multiply, p_i, p_i); // i * i
            return global::System.Linq.Expressions.Expression.Lambda<global::System.Func<int, int>>(expr_0, p_i);
        }
    }
}


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

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


// === 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.IntExtensions).GetMethod("Squared", allFlags, null, new global::System.Type[] { typeof(int) }, null), "ExpressiveSharp.Generated.ExpressiveSharp_Docs_Playground_Snippet_IntExtensions", "Squared_P0_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, "DXo3tMnPIjU9x5Qq7/UC/IIBAABfX1NuaXBwZXQuY3M=")]
        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, SquaredQty = i.Quantity.Squared() }
            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("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.IntExtensions).GetMethod("Squared", global::System.Reflection.BindingFlags.Public | global::System.Reflection.BindingFlags.NonPublic | global::System.Reflection.BindingFlags.Static, null, new global::System.Type[] { typeof(int) }, null), new global::System.Linq.Expressions.Expression[] { i3e6114c24_expr_3 });
            var i3e6114c24_expr_4 = typeof(T1).GetConstructors()[0];
            var i3e6114c24_expr_0 = global::System.Linq.Expressions.Expression.New(i3e6114c24_expr_4, new global::System.Linq.Expressions.Expression[] { i3e6114c24_expr_1, i3e6114c24_expr_2 }, new global::System.Reflection.MemberInfo[] { typeof(T1).GetProperty("Id"), typeof(T1).GetProperty("SquaredQty") });
            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 →

db
    .LineItems
    .Select(i => new { i.Id, SquaredQty = i.Quantity.Squared() })

// Setup
public static class IntExtensions
{
    [Expressive]
    public static int Squared(this int i) => i * i;
}

Generated SQL:

SELECT "l"."Id", "l"."Quantity" * "l"."Quantity" AS "SquaredQty"
FROM "LineItems" AS "l"

Composing Extension Methods

Extension methods can reference other [Expressive] members -- properties, methods, or other extension methods. ExpandExpressives() resolves them transitively:

C#

db
    .Customers
    .Where(c => c.IsVip())

// Setup
public static class CustomerExtensions
{
    [Expressive]
    public static decimal TotalSpent(this Customer c)
        => c.Orders.Sum(o => o.Items.Sum(i => i.UnitPrice * i.Quantity));

    [Expressive]
    public static bool IsVip(this Customer c)
        => c.TotalSpent() > 10000m;   // calls another [Expressive] extension
}

SELECT "c"."Id", "c"."Country", "c"."Email", "c"."JoinedAt", "c"."Name"
FROM "Customers" AS "c"
WHERE ef_compare((
    SELECT COALESCE(ef_sum((
        SELECT COALESCE(ef_sum(ef_multiply("l"."UnitPrice", CAST("l"."Quantity" AS TEXT))), '0.0')
        FROM "LineItems" AS "l"
        WHERE "o"."Id" = "l"."OrderId")), '0.0')
    FROM "Orders" AS "o"
    WHERE "c"."Id" = "o"."CustomerId"), '10000.0') > 0

SELECT c."Id", c."Country", c."Email", c."JoinedAt", c."Name"
FROM "Customers" AS c
WHERE (
    SELECT COALESCE(sum((
        SELECT COALESCE(sum(l."UnitPrice" * l."Quantity"::numeric(18,2)), 0.0)
        FROM "LineItems" AS l
        WHERE o."Id" = l."OrderId")), 0.0)
    FROM "Orders" AS o
    WHERE c."Id" = o."CustomerId") > 10000.0

SELECT [c].[Id], [c].[Country], [c].[Email], [c].[JoinedAt], [c].[Name]
FROM [Customers] AS [c]
WHERE (
    SELECT COALESCE(SUM([s].[value]), 0.0)
    FROM [Orders] AS [o]
    OUTER APPLY (
        SELECT COALESCE(SUM([l].[UnitPrice] * CAST([l].[Quantity] AS decimal(18,2))), 0.0) AS [value]
        FROM [LineItems] AS [l]
        WHERE [o].[Id] = [l].[OrderId]
    ) AS [s]
    WHERE [c].[Id] = [o].[CustomerId]) > 10000.0

playground.customers.Aggregate([
    {
         "$match" : {
             "$expr" : {
                 "$gt" : [
                    {
                         "$sum" : {
                             "$map" : {
                                 "input" : "$Orders",
                                "as" : "o",
                                "in" : {
                                     "$sum" : {
                                         "$map" : {
                                             "input" : "$$o.Items",
                                            "as" : "i",
                                            "in" : {
                                                 "$multiply" : ["$$i.UnitPrice", "$$i.Quantity"] 
                                            } 
                                        } 
                                    } 
                                } 
                            } 
                        } 
                    },
                    { "$numberDecimal" : "10000" }
                ] 
            } 
        } 
    }
])

// === ExpressiveSharp_Docs_Playground_Snippet_CustomerExtensions.TotalSpent_P0_ExpressiveSharp_Docs_PlaygroundModel_Webshop_Customer.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_CustomerExtensions 
    {
        // [Expressive]
        // public static decimal TotalSpent(this Customer c) => c.Orders.Sum(o => o.Items.Sum(i => i.UnitPrice * i.Quantity));
        static global::System.Linq.Expressions.Expression<global::System.Func<global::ExpressiveSharp.Docs.PlaygroundModel.Webshop.Customer, decimal>> TotalSpent_P0_ExpressiveSharp_Docs_PlaygroundModel_Webshop_Customer_Expression() 
        {
            var p_c = global::System.Linq.Expressions.Expression.Parameter(typeof(global::ExpressiveSharp.Docs.PlaygroundModel.Webshop.Customer), "c");
            var expr_1 = global::System.Linq.Expressions.Expression.Property(p_c, typeof(global::ExpressiveSharp.Docs.PlaygroundModel.Webshop.Customer).GetProperty("Orders", global::System.Reflection.BindingFlags.Public | global::System.Reflection.BindingFlags.NonPublic | global::System.Reflection.BindingFlags.Instance)); // c.Orders
            var p_o_2 = global::System.Linq.Expressions.Expression.Parameter(typeof(global::ExpressiveSharp.Docs.PlaygroundModel.Webshop.Order), "o"); // o => o.Items.Sum(i => i.UnitPrice * i.Quantity)
            var expr_4 = global::System.Linq.Expressions.Expression.Property(p_o_2, 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_5 = global::System.Linq.Expressions.Expression.Parameter(typeof(global::ExpressiveSharp.Docs.PlaygroundModel.Webshop.LineItem), "i"); // i => i.UnitPrice * i.Quantity
            var expr_7 = global::System.Linq.Expressions.Expression.Property(p_i_5, 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_9 = global::System.Linq.Expressions.Expression.Property(p_i_5, 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_8 = global::System.Linq.Expressions.Expression.Convert(expr_9, typeof(decimal));
            var expr_6 = global::System.Linq.Expressions.Expression.MakeBinary(global::System.Linq.Expressions.ExpressionType.Multiply, expr_7, expr_8);
            var expr_10 = global::System.Linq.Expressions.Expression.Lambda<global::System.Func<global::ExpressiveSharp.Docs.PlaygroundModel.Webshop.LineItem, decimal>>(expr_6, p_i_5);
            var expr_3 = 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_4, expr_10 });
            var expr_11 = global::System.Linq.Expressions.Expression.Lambda<global::System.Func<global::ExpressiveSharp.Docs.PlaygroundModel.Webshop.Order, decimal>>(expr_3, p_o_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.Order)), new global::System.Linq.Expressions.Expression[] { expr_1, expr_11 });
            return global::System.Linq.Expressions.Expression.Lambda<global::System.Func<global::ExpressiveSharp.Docs.PlaygroundModel.Webshop.Customer, decimal>>(expr_0, p_c);
        }
    }
}


// === ExpressiveSharp_Docs_Playground_Snippet_CustomerExtensions.IsVip_P0_ExpressiveSharp_Docs_PlaygroundModel_Webshop_Customer.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_CustomerExtensions 
    {
        // [Expressive]
        // public static bool IsVip(this Customer c) => c.TotalSpent() > 10000m; // calls another [Expressive] extension
        // 
        static global::System.Linq.Expressions.Expression<global::System.Func<global::ExpressiveSharp.Docs.PlaygroundModel.Webshop.Customer, bool>> IsVip_P0_ExpressiveSharp_Docs_PlaygroundModel_Webshop_Customer_Expression() 
        {
            var p_c = global::System.Linq.Expressions.Expression.Parameter(typeof(global::ExpressiveSharp.Docs.PlaygroundModel.Webshop.Customer), "c");
            var expr_1 = global::System.Linq.Expressions.Expression.Call(typeof(global::ExpressiveSharp.Docs.Playground.Snippet.CustomerExtensions).GetMethod("TotalSpent", 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.Customer) }, null), new global::System.Linq.Expressions.Expression[] { p_c }); // c.TotalSpent()
            var expr_2 = global::System.Linq.Expressions.Expression.Constant(10000m, typeof(decimal)); // 10000m
            var expr_0 = global::System.Linq.Expressions.Expression.MakeBinary(global::System.Linq.Expressions.ExpressionType.GreaterThan, expr_1, expr_2);
            return global::System.Linq.Expressions.Expression.Lambda<global::System.Func<global::ExpressiveSharp.Docs.PlaygroundModel.Webshop.Customer, bool>>(expr_0, p_c);
        }
    }
}


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

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


// === 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.CustomerExtensions).GetMethod("TotalSpent", allFlags, null, new global::System.Type[] { typeof(global::ExpressiveSharp.Docs.PlaygroundModel.Webshop.Customer) }, null), "ExpressiveSharp.Generated.ExpressiveSharp_Docs_Playground_Snippet_CustomerExtensions", "TotalSpent_P0_ExpressiveSharp_Docs_PlaygroundModel_Webshop_Customer_Expression");
            Register(map, typeof(global::ExpressiveSharp.Docs.Playground.Snippet.CustomerExtensions).GetMethod("IsVip", allFlags, null, new global::System.Type[] { typeof(global::ExpressiveSharp.Docs.PlaygroundModel.Webshop.Customer) }, null), "ExpressiveSharp.Generated.ExpressiveSharp_Docs_Playground_Snippet_CustomerExtensions", "IsVip_P0_ExpressiveSharp_Docs_PlaygroundModel_Webshop_Customer_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, "8WP7gYAhAMt5kw01AKs0cIIBAABfX1NuaXBwZXQuY3M=")]
        internal static global::ExpressiveSharp.IExpressiveQueryable<global::ExpressiveSharp.Docs.PlaygroundModel.Webshop.Customer> __Polyfill_Where_3e61_14_24(
            this global::ExpressiveSharp.IExpressiveQueryable<global::ExpressiveSharp.Docs.PlaygroundModel.Webshop.Customer> source,
            global::System.Func<global::ExpressiveSharp.Docs.PlaygroundModel.Webshop.Customer, bool> __func)
        {
            // Source: c => c.IsVip()
            var i3e6114c24_p_c = global::System.Linq.Expressions.Expression.Parameter(typeof(global::ExpressiveSharp.Docs.PlaygroundModel.Webshop.Customer), "c");
            var i3e6114c24_expr_0 = global::System.Linq.Expressions.Expression.Call(typeof(global::ExpressiveSharp.Docs.Playground.Snippet.CustomerExtensions).GetMethod("IsVip", 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.Customer) }, null), new global::System.Linq.Expressions.Expression[] { i3e6114c24_p_c }); // c.IsVip()
            var __lambda = global::System.Linq.Expressions.Expression.Lambda<global::System.Func<global::ExpressiveSharp.Docs.PlaygroundModel.Webshop.Customer, bool>>(i3e6114c24_expr_0, i3e6114c24_p_c);
            return global::ExpressiveSharp.ExpressiveQueryableExtensions.AsExpressive(
                global::System.Linq.Queryable.Where(
                    (global::System.Linq.IQueryable<global::ExpressiveSharp.Docs.PlaygroundModel.Webshop.Customer>)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 →

db
    .Customers
    .Where(c => c.IsVip())

// Setup
public static class CustomerExtensions
{
    [Expressive]
    public static decimal TotalSpent(this Customer c)
        => c.Orders.Sum(o => o.Items.Sum(i => i.UnitPrice * i.Quantity));

    [Expressive]
    public static bool IsVip(this Customer c)
        => c.TotalSpent() > 10000m;   // calls another [Expressive] extension
}

Generated SQL:

SELECT "c"."Id", "c"."Country", "c"."Email", "c"."JoinedAt", "c"."Name"
FROM "Customers" AS "c"
WHERE ef_compare((
    SELECT COALESCE(ef_sum((
        SELECT COALESCE(ef_sum(ef_multiply("l"."UnitPrice", CAST("l"."Quantity" AS TEXT))), '0.0')
        FROM "LineItems" AS "l"
        WHERE "o"."Id" = "l"."OrderId")), '0.0')
    FROM "Orders" AS "o"
    WHERE "c"."Id" = "o"."CustomerId"), '10000.0') > 0

C# 14 Extension Members (.NET 10+)

On .NET 10 with C# 14, you can use the new extension(T) syntax to define extension properties and methods. This is cleaner than traditional extension methods for property-like logic:

public static class OrderExtensions
{
    extension(Order o)
    {
        [Expressive]
        public decimal Total => o.Items.Sum(i => i.UnitPrice * i.Quantity);

        [Expressive]
        public string Grade => o.Items.Sum(i => i.UnitPrice * i.Quantity) switch
        {
            >= 1000m => "Premium",
            >= 100m  => "Standard",
            _        => "Budget",
        };

        [Expressive]
        public int ScaledItemCount(int factor) => o.Items.Count() * factor;
    }
}

// Use like any other property/method:
var orders = db.Orders
    .Where(o => o.Total > 500m)
    .Select(o => new { o.Id, o.Total, o.Grade });

Extension Members on Primitives and Interfaces

C# 14 extensions work on any type, including primitives and interfaces:

public static class IntExtensions
{
    extension(int i)
    {
        [Expressive]
        public int Squared => i * i;
    }
}

db.LineItems.Select(i => new { i.Id, SquaredQty = i.Quantity.Squared });

Block Bodies and Switch Expressions

C# 14 extension members support all the same features as regular [Expressive] members -- block bodies, switch expressions, pattern matching, and null-conditional operators:

public static class OrderExtensions
{
    extension(Order o)
    {
        [Expressive(AllowBlockBody = true)]
        public string GetStatus()
        {
            if (o.Status == OrderStatus.Delivered && o.Items.Count() > 0)
                return "Completed";
            return "In Progress";
        }

        [Expressive]
        public bool IsHighValue => o.Items.Sum(i => i.UnitPrice * i.Quantity) is > 100m;
    }
}

.NET 10+ Only

C# 14 extension members require .NET 10 or later. On .NET 8, use traditional extension methods in static classes instead.

Extension Methods vs [ExpressiveFor]

Both let you add query logic to types you don't own, but they serve different purposes:

	Extension Methods	[ExpressiveFor]
Purpose	Add new query logic	Provide an expression body for an existing method
Call site	entity.MyExtension()	Math.Clamp(value, min, max) (original call site)
When to use	You're adding new functionality	You want an existing method (BCL, third-party) to become translatable

See [ExpressiveFor] Mapping for details on mapping existing members.

Important Rules

• Traditional extension methods must be in a static class.
• C# 14 extension members must be in a static class with an extension(T) block.
• The this parameter (or extension(T) parameter) represents the entity instance in the generated expression.
• All standard [Expressive] features work: AllowBlockBody, Transformers, composition with other [Expressive] members.

See Also

• [Expressive] Properties -- defining computed properties on entities directly
• [Expressive] Methods -- defining computed methods on entities
• Reusable Query Filters -- practical example of extension methods as reusable filters
• [ExpressiveFor] Mapping -- mapping existing methods on types you don't own