ExpressiveSharp

Appearance

Constructor Projections ​

Mark a constructor with [Expressive] to project your DTOs directly inside LINQ queries. The generator emits a MemberInit expression (new T() { Prop = value, ... }) that your LINQ provider can translate to a native projection.

Why Constructor Projections? ​

Without constructor projections, you must write inline anonymous types or repeat object-initializer logic in every query:

C#
db
    .Orders
    .Select(o => new OrderSummaryDto
    {
        Id = o.Id,
        Description = $"Order #{o.Id}",
        Total = o.Items.Sum(i => i.UnitPrice * i.Quantity),
    })

// Setup
public class OrderSummaryDto
{
    public int Id { get; set; }
    public string Description { get; set; } = "";
    public decimal Total { get; set; }
}
SELECT "o"."Id", 'Order #' || CAST("o"."Id" AS TEXT) AS "Description", (
    SELECT COALESCE(ef_sum(ef_multiply("l"."UnitPrice", CAST("l"."Quantity" AS TEXT))), '0.0')
    FROM "LineItems" AS "l"
    WHERE "o"."Id" = "l"."OrderId") AS "Total"
FROM "Orders" AS "o"
SELECT o."Id", 'Order #' || o."Id"::text AS "Description", (
    SELECT COALESCE(sum(l."UnitPrice" * l."Quantity"::numeric(18,2)), 0.0)
    FROM "LineItems" AS l
    WHERE o."Id" = l."OrderId") AS "Total"
FROM "Orders" AS o
SELECT [o].[Id], N'Order #' + CONVERT(varchar(11), [o].[Id]) AS [Description], (
    SELECT COALESCE(SUM([l].[UnitPrice] * CAST([l].[Quantity] AS decimal(18,2))), 0.0)
    FROM [LineItems] AS [l]
    WHERE [o].[Id] = [l].[OrderId]) AS [Total]
FROM [Orders] AS [o]
playground.orders.Aggregate([
    {
         "$project" : {
             "_id" : "$_id",
            "Description" : {
                 "$concat" : [
                    "Order #",
                    { "$toString" : "$_id" }
                ] 
            },
            "Total" : {
                 "$sum" : {
                     "$map" : {
                         "input" : "$Items",
                        "as" : "i",
                        "in" : {
                             "$multiply" : ["$$i.UnitPrice", "$$i.Quantity"] 
                        } 
                    } 
                } 
            } 
        } 
    }
])
// === PolyfillInterceptors_b1293e61.g.cs ===
// <auto-generated/>
#nullable disable

namespace ExpressiveSharp.Generated.Interceptors
{
    internal static partial class PolyfillInterceptors
    {
        [global::System.Runtime.CompilerServices.InterceptsLocationAttribute(1, "qUsNY3N7K/6XRy0rptbmtYQBAABfX1NuaXBwZXQuY3M=")]
        internal static global::ExpressiveSharp.IExpressiveQueryable<global::ExpressiveSharp.Docs.Playground.Snippet.OrderSummaryDto> __Polyfill_Select_3e61_15_5(
            this global::ExpressiveSharp.IExpressiveQueryable<global::ExpressiveSharp.Docs.PlaygroundModel.Webshop.Order> source,
            global::System.Func<global::ExpressiveSharp.Docs.PlaygroundModel.Webshop.Order, global::ExpressiveSharp.Docs.Playground.Snippet.OrderSummaryDto> __func)
        {
            // Source: o => new OrderSummaryDto { Id = o.Id, Description = $"Order #{o.Id}", Total = o.Items.Sum(i => i.UnitPrice * i.Quantity), }
            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.New(typeof(global::ExpressiveSharp.Docs.Playground.Snippet.OrderSummaryDto).GetConstructor(global::System.Reflection.BindingFlags.Public | global::System.Reflection.BindingFlags.NonPublic | global::System.Reflection.BindingFlags.Instance, null, new global::System.Type[] {  }, null)); // new OrderSummaryDto     {         Id = o.Id,         Desc...
            var i3e6115c5_expr_2 = global::System.Linq.Expressions.Expression.Property(i3e6115c5_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 i3e6115c5_expr_3 = global::System.Linq.Expressions.Expression.Bind(typeof(global::ExpressiveSharp.Docs.Playground.Snippet.OrderSummaryDto).GetProperty("Id", global::System.Reflection.BindingFlags.Public | global::System.Reflection.BindingFlags.NonPublic | global::System.Reflection.BindingFlags.Instance), i3e6115c5_expr_2);
            var i3e6115c5_expr_4 = global::System.Linq.Expressions.Expression.Constant("Order #", typeof(string)); // $"Order #{o.Id}"
            var i3e6115c5_expr_5 = global::System.Linq.Expressions.Expression.Property(i3e6115c5_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 i3e6115c5_expr_6 = global::System.Linq.Expressions.Expression.Call(i3e6115c5_expr_5, typeof(int).GetMethod("ToString", global::System.Reflection.BindingFlags.Public | global::System.Reflection.BindingFlags.NonPublic | global::System.Reflection.BindingFlags.Instance, null, new global::System.Type[] {  }, null));
            var i3e6115c5_expr_7 = global::System.Linq.Expressions.Expression.Call(typeof(string).GetMethod("Concat", 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), i3e6115c5_expr_4, i3e6115c5_expr_6);
            var i3e6115c5_expr_8 = global::System.Linq.Expressions.Expression.Bind(typeof(global::ExpressiveSharp.Docs.Playground.Snippet.OrderSummaryDto).GetProperty("Description", global::System.Reflection.BindingFlags.Public | global::System.Reflection.BindingFlags.NonPublic | global::System.Reflection.BindingFlags.Instance), i3e6115c5_expr_7);
            var i3e6115c5_expr_10 = global::System.Linq.Expressions.Expression.Property(i3e6115c5_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_11 = global::System.Linq.Expressions.Expression.Parameter(typeof(global::ExpressiveSharp.Docs.PlaygroundModel.Webshop.LineItem), "i"); // i => i.UnitPrice * i.Quantity
            var i3e6115c5_expr_13 = global::System.Linq.Expressions.Expression.Property(p_i_11, 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 i3e6115c5_expr_15 = global::System.Linq.Expressions.Expression.Property(p_i_11, 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 i3e6115c5_expr_14 = global::System.Linq.Expressions.Expression.Convert(i3e6115c5_expr_15, typeof(decimal));
            var i3e6115c5_expr_12 = global::System.Linq.Expressions.Expression.MakeBinary(global::System.Linq.Expressions.ExpressionType.Multiply, i3e6115c5_expr_13, i3e6115c5_expr_14);
            var i3e6115c5_expr_16 = global::System.Linq.Expressions.Expression.Lambda<global::System.Func<global::ExpressiveSharp.Docs.PlaygroundModel.Webshop.LineItem, decimal>>(i3e6115c5_expr_12, p_i_11);
            var i3e6115c5_expr_9 = 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[] { i3e6115c5_expr_10, i3e6115c5_expr_16 });
            var i3e6115c5_expr_17 = global::System.Linq.Expressions.Expression.Bind(typeof(global::ExpressiveSharp.Docs.Playground.Snippet.OrderSummaryDto).GetProperty("Total", global::System.Reflection.BindingFlags.Public | global::System.Reflection.BindingFlags.NonPublic | global::System.Reflection.BindingFlags.Instance), i3e6115c5_expr_9);
            var i3e6115c5_expr_0 = global::System.Linq.Expressions.Expression.MemberInit(i3e6115c5_expr_1, i3e6115c5_expr_3, i3e6115c5_expr_8, i3e6115c5_expr_17);
            var __lambda = global::System.Linq.Expressions.Expression.Lambda<global::System.Func<global::ExpressiveSharp.Docs.PlaygroundModel.Webshop.Order, global::ExpressiveSharp.Docs.Playground.Snippet.OrderSummaryDto>>(i3e6115c5_expr_0, i3e6115c5_p_o);
            return global::ExpressiveSharp.ExpressiveQueryableExtensions.AsExpressive(
                global::System.Linq.Queryable.Select(
                    (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 →

With an [Expressive] constructor, you define the projection once and use it everywhere:

C#
db
    .Orders
    .Select(o => new OrderSummaryDto(o.Id, $"Order #{o.Id}", o.Total()))

// Setup
public class OrderSummaryDto
{
    public int Id { get; set; }
    public string Description { get; set; } = "";
    public decimal Total { get; set; }

    public OrderSummaryDto() { }

    [Expressive]
    public OrderSummaryDto(int id, string description, decimal total)
    {
        Id = id;
        Description = description;
        Total = total;
    }
}

public static class OrderExt
{
    [Expressive]
    public static decimal Total(this Order o)
        => o.Items.Sum(i => i.UnitPrice * i.Quantity);
}
SELECT "o"."Id", 'Order #' || CAST("o"."Id" AS TEXT) AS "Description", (
    SELECT COALESCE(ef_sum(ef_multiply("l"."UnitPrice", CAST("l"."Quantity" AS TEXT))), '0.0')
    FROM "LineItems" AS "l"
    WHERE "o"."Id" = "l"."OrderId") AS "Total"
FROM "Orders" AS "o"
SELECT o."Id", 'Order #' || o."Id"::text AS "Description", (
    SELECT COALESCE(sum(l."UnitPrice" * l."Quantity"::numeric(18,2)), 0.0)
    FROM "LineItems" AS l
    WHERE o."Id" = l."OrderId") AS "Total"
FROM "Orders" AS o
SELECT [o].[Id], N'Order #' + CONVERT(varchar(11), [o].[Id]) AS [Description], (
    SELECT COALESCE(SUM([l].[UnitPrice] * CAST([l].[Quantity] AS decimal(18,2))), 0.0)
    FROM [LineItems] AS [l]
    WHERE [o].[Id] = [l].[OrderId]) AS [Total]
FROM [Orders] AS [o]
playground.orders.Aggregate([
    {
         "$project" : {
             "_id" : "$_id",
            "Description" : {
                 "$concat" : [
                    "Order #",
                    { "$toString" : "$_id" }
                ] 
            },
            "Total" : {
                 "$sum" : {
                     "$map" : {
                         "input" : "$Items",
                        "as" : "i",
                        "in" : {
                             "$multiply" : ["$$i.UnitPrice", "$$i.Quantity"] 
                        } 
                    } 
                } 
            } 
        } 
    }
])
// === ExpressiveSharp_Docs_Playground_Snippet_OrderSummaryDto._ctor_P0_int_P1_string_P2_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_OrderSummaryDto 
    {
        // [Expressive]
        // public OrderSummaryDto(int id, string description, decimal total)
        // {
        //     Id = id;
        //     Description = description;
        //     Total = total;
        // }
        static global::System.Linq.Expressions.Expression<global::System.Func<int, string, decimal, global::ExpressiveSharp.Docs.Playground.Snippet.OrderSummaryDto>> _ctor_P0_int_P1_string_P2_decimal_Expression() 
        {
            var p_id = global::System.Linq.Expressions.Expression.Parameter(typeof(int), "id");
            var p_description = global::System.Linq.Expressions.Expression.Parameter(typeof(string), "description");
            var p_total = global::System.Linq.Expressions.Expression.Parameter(typeof(decimal), "total");
            var expr_0 = global::System.Linq.Expressions.Expression.New(typeof(global::ExpressiveSharp.Docs.Playground.Snippet.OrderSummaryDto).GetConstructor(global::System.Reflection.BindingFlags.Public | global::System.Reflection.BindingFlags.NonPublic | global::System.Reflection.BindingFlags.Instance, null, new global::System.Type[] {  }, null));
            var expr_1 = global::System.Linq.Expressions.Expression.Bind(typeof(global::ExpressiveSharp.Docs.Playground.Snippet.OrderSummaryDto).GetProperty("Id", global::System.Reflection.BindingFlags.Public | global::System.Reflection.BindingFlags.NonPublic | global::System.Reflection.BindingFlags.Instance), p_id);
            var expr_2 = global::System.Linq.Expressions.Expression.Bind(typeof(global::ExpressiveSharp.Docs.Playground.Snippet.OrderSummaryDto).GetProperty("Description", global::System.Reflection.BindingFlags.Public | global::System.Reflection.BindingFlags.NonPublic | global::System.Reflection.BindingFlags.Instance), p_description);
            var expr_3 = global::System.Linq.Expressions.Expression.Bind(typeof(global::ExpressiveSharp.Docs.Playground.Snippet.OrderSummaryDto).GetProperty("Total", global::System.Reflection.BindingFlags.Public | global::System.Reflection.BindingFlags.NonPublic | global::System.Reflection.BindingFlags.Instance), p_total);
            var expr_4 = global::System.Linq.Expressions.Expression.MemberInit(expr_0, expr_1, expr_2, expr_3);
            return global::System.Linq.Expressions.Expression.Lambda<global::System.Func<int, string, decimal, global::ExpressiveSharp.Docs.Playground.Snippet.OrderSummaryDto>>(expr_4, p_id, p_description, p_total);
        }
    }
}


// === ExpressiveSharp_Docs_Playground_Snippet_OrderExt.Total_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 Total(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>> Total_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_OrderSummaryDto.Attributes.g.cs ===
// <auto-generated/>

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


// === 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.OrderSummaryDto).GetConstructor(allFlags, null, new global::System.Type[] { typeof(int), typeof(string), typeof(decimal) }, null), "ExpressiveSharp.Generated.ExpressiveSharp_Docs_Playground_Snippet_OrderSummaryDto", "_ctor_P0_int_P1_string_P2_decimal_Expression");
            Register(map, typeof(global::ExpressiveSharp.Docs.Playground.Snippet.OrderExt).GetMethod("Total", allFlags, null, new global::System.Type[] { typeof(global::ExpressiveSharp.Docs.PlaygroundModel.Webshop.Order) }, null), "ExpressiveSharp.Generated.ExpressiveSharp_Docs_Playground_Snippet_OrderExt", "Total_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, "SD5GwIsXxLHe2o+lD0/a238BAABfX1NuaXBwZXQuY3M=")]
        internal static global::ExpressiveSharp.IExpressiveQueryable<global::ExpressiveSharp.Docs.Playground.Snippet.OrderSummaryDto> __Polyfill_Select_3e61_14_21(
            this global::ExpressiveSharp.IExpressiveQueryable<global::ExpressiveSharp.Docs.PlaygroundModel.Webshop.Order> source,
            global::System.Func<global::ExpressiveSharp.Docs.PlaygroundModel.Webshop.Order, global::ExpressiveSharp.Docs.Playground.Snippet.OrderSummaryDto> __func)
        {
            // Source: o => new OrderSummaryDto(o.Id, $"Order #{o.Id}", o.Total())
            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.Property(i3e6114c21_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 i3e6114c21_expr_2 = global::System.Linq.Expressions.Expression.Constant("Order #", typeof(string)); // $"Order #{o.Id}"
            var i3e6114c21_expr_3 = global::System.Linq.Expressions.Expression.Property(i3e6114c21_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 i3e6114c21_expr_4 = global::System.Linq.Expressions.Expression.Call(i3e6114c21_expr_3, typeof(int).GetMethod("ToString", global::System.Reflection.BindingFlags.Public | global::System.Reflection.BindingFlags.NonPublic | global::System.Reflection.BindingFlags.Instance, null, new global::System.Type[] {  }, null));
            var i3e6114c21_expr_5 = global::System.Linq.Expressions.Expression.Call(typeof(string).GetMethod("Concat", 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), i3e6114c21_expr_2, i3e6114c21_expr_4);
            var i3e6114c21_expr_6 = global::System.Linq.Expressions.Expression.Call(typeof(global::ExpressiveSharp.Docs.Playground.Snippet.OrderExt).GetMethod("Total", 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[] { i3e6114c21_p_o }); // o.Total()
            var i3e6114c21_expr_0 = global::System.Linq.Expressions.Expression.New(typeof(global::ExpressiveSharp.Docs.Playground.Snippet.OrderSummaryDto).GetConstructor(global::System.Reflection.BindingFlags.Public | global::System.Reflection.BindingFlags.NonPublic | global::System.Reflection.BindingFlags.Instance, null, new global::System.Type[] { typeof(int), typeof(string), typeof(decimal) }, null), i3e6114c21_expr_1, i3e6114c21_expr_5, i3e6114c21_expr_6);
            var __lambda = global::System.Linq.Expressions.Expression.Lambda<global::System.Func<global::ExpressiveSharp.Docs.PlaygroundModel.Webshop.Order, global::ExpressiveSharp.Docs.Playground.Snippet.OrderSummaryDto>>(i3e6114c21_expr_0, i3e6114c21_p_o);
            return global::ExpressiveSharp.ExpressiveQueryableExtensions.AsExpressive(
                global::System.Linq.Queryable.Select(
                    (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 →

Basic Example ​

csharp
public class OrderSummaryDto
{
    public int Id { get; set; }
    public string Description { get; set; } = "";
    public decimal Total { get; set; }

    public OrderSummaryDto() { }   // required parameterless constructor

    [Expressive]
    public OrderSummaryDto(int id, string description, decimal total)
    {
        Id = id;
        Description = description;
        Total = total;
    }
}

The generator produces an expression equivalent to:

csharp
(int id, string description, decimal total) => new OrderSummaryDto()
{
    Id = id,
    Description = description,
    Total = total
}

Use it in a query -- the query tabs above show how each provider translates the projection.

TIP

o.Total() is itself an [Expressive] extension -- it is expanded recursively into o.Items.Sum(i => i.UnitPrice * i.Quantity) before translation. Constructor projections compose with expressive properties and methods seamlessly.

Requirements ​

The class must expose an accessible parameterless constructor (public, internal, or protected-internal). The generated code uses new T() { ... } (object-initializer syntax), which requires a parameterless constructor.

If the parameterless constructor is missing, the generator reports EXP0002.

Supported Constructs ​

Constructor bodies support the following constructs:

ConstructNotes
Simple property assignmentsId = id; Description = description;
Local variable declarationsInlined at each usage point
if/else chainsConverted to ternary expressions / provider CASE
Switch expressionsTranslated to nested ternary / CASE
base()/this() initializer chainsRecursively inlines the delegated constructor's assignments

Inheritance -- Base/This Initializer Chains ​

The generator recursively inlines delegated constructor assignments. This is useful with DTO inheritance hierarchies:

C#
db
    .Customers
    .Select(c => new CustomerDetailDto(c))

// Setup
public class CustomerDto
{
    public int Id { get; set; }
    public string Name { get; set; } = "";

    public CustomerDto() { }

    [Expressive]
    public CustomerDto(Customer c)
    {
        Id = c.Id;
        Name = c.Name;
    }
}

public class CustomerDetailDto : CustomerDto
{
    public string? Email { get; set; }
    public string Tier { get; set; } = "";

    public CustomerDetailDto() { }

    [Expressive]
    public CustomerDetailDto(Customer c) : base(c)
    {
        Email = c.Email;
        Tier = c.Orders.Count() >= 10 ? "Gold" : "Standard";
    }
}
SELECT "c"."Email", CASE
    WHEN (
        SELECT COUNT(*)
        FROM "Orders" AS "o"
        WHERE "c"."Id" = "o"."CustomerId") >= 10 THEN 'Gold'
    ELSE 'Standard'
END AS "Tier"
FROM "Customers" AS "c"
SELECT c."Email", CASE
    WHEN (
        SELECT count(*)::int
        FROM "Orders" AS o
        WHERE c."Id" = o."CustomerId") >= 10 THEN 'Gold'
    ELSE 'Standard'
END AS "Tier"
FROM "Customers" AS c
SELECT [c].[Email], CASE
    WHEN (
        SELECT COUNT(*)
        FROM [Orders] AS [o]
        WHERE [c].[Id] = [o].[CustomerId]) >= 10 THEN N'Gold'
    ELSE N'Standard'
END AS [Tier]
FROM [Customers] AS [c]
playground.customers.Aggregate([
    {
         "$project" : {
             "Email" : "$Email",
            "Tier" : {
                 "$cond" : {
                     "if" : {
                         "$gte" : [
                            { "$size" : "$Orders" },
                            10
                        ] 
                    },
                    "then" : "Gold",
                    "else" : "Standard" 
                } 
            },
            "_id" : 0 
        } 
    }
])
// === ExpressiveSharp_Docs_Playground_Snippet_CustomerDto._ctor_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_CustomerDto 
    {
        // [Expressive]
        // public CustomerDto(Customer c)
        // {
        //     Id = c.Id;
        //     Name = c.Name;
        // }
        static global::System.Linq.Expressions.Expression<global::System.Func<global::ExpressiveSharp.Docs.PlaygroundModel.Webshop.Customer, global::ExpressiveSharp.Docs.Playground.Snippet.CustomerDto>> _ctor_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_0 = global::System.Linq.Expressions.Expression.New(typeof(global::ExpressiveSharp.Docs.Playground.Snippet.CustomerDto).GetConstructor(global::System.Reflection.BindingFlags.Public | global::System.Reflection.BindingFlags.NonPublic | global::System.Reflection.BindingFlags.Instance, null, new global::System.Type[] {  }, null));
            var expr_1 = global::System.Linq.Expressions.Expression.Property(p_c, typeof(global::ExpressiveSharp.Docs.PlaygroundModel.Webshop.Customer).GetProperty("Id", global::System.Reflection.BindingFlags.Public | global::System.Reflection.BindingFlags.NonPublic | global::System.Reflection.BindingFlags.Instance)); // c.Id
            var expr_2 = global::System.Linq.Expressions.Expression.Property(p_c, typeof(global::ExpressiveSharp.Docs.PlaygroundModel.Webshop.Customer).GetProperty("Name", global::System.Reflection.BindingFlags.Public | global::System.Reflection.BindingFlags.NonPublic | global::System.Reflection.BindingFlags.Instance)); // c.Name
            var expr_3 = global::System.Linq.Expressions.Expression.Bind(typeof(global::ExpressiveSharp.Docs.Playground.Snippet.CustomerDto).GetProperty("Id", global::System.Reflection.BindingFlags.Public | global::System.Reflection.BindingFlags.NonPublic | global::System.Reflection.BindingFlags.Instance), expr_1);
            var expr_4 = global::System.Linq.Expressions.Expression.Bind(typeof(global::ExpressiveSharp.Docs.Playground.Snippet.CustomerDto).GetProperty("Name", global::System.Reflection.BindingFlags.Public | global::System.Reflection.BindingFlags.NonPublic | global::System.Reflection.BindingFlags.Instance), expr_2);
            var expr_5 = global::System.Linq.Expressions.Expression.MemberInit(expr_0, expr_3, expr_4);
            return global::System.Linq.Expressions.Expression.Lambda<global::System.Func<global::ExpressiveSharp.Docs.PlaygroundModel.Webshop.Customer, global::ExpressiveSharp.Docs.Playground.Snippet.CustomerDto>>(expr_5, p_c);
        }
    }
}


// === ExpressiveSharp_Docs_Playground_Snippet_CustomerDetailDto._ctor_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_CustomerDetailDto 
    {
        // [Expressive]
        // public CustomerDetailDto(Customer c) : base(c)
        // {
        //     Email = c.Email;
        //     Tier = c.Orders.Count() >= 10 ? "Gold" : "Standard";
        // }
        static global::System.Linq.Expressions.Expression<global::System.Func<global::ExpressiveSharp.Docs.PlaygroundModel.Webshop.Customer, global::ExpressiveSharp.Docs.Playground.Snippet.CustomerDetailDto>> _ctor_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_0 = global::System.Linq.Expressions.Expression.New(typeof(global::ExpressiveSharp.Docs.Playground.Snippet.CustomerDetailDto).GetConstructor(global::System.Reflection.BindingFlags.Public | global::System.Reflection.BindingFlags.NonPublic | global::System.Reflection.BindingFlags.Instance, null, new global::System.Type[] {  }, null));
            var expr_1 = global::System.Linq.Expressions.Expression.Property(p_c, typeof(global::ExpressiveSharp.Docs.PlaygroundModel.Webshop.Customer).GetProperty("Email", global::System.Reflection.BindingFlags.Public | global::System.Reflection.BindingFlags.NonPublic | global::System.Reflection.BindingFlags.Instance)); // c.Email
            var expr_5 = 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 expr_4 = 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 == "Count" && m.IsGenericMethodDefinition && m.GetGenericArguments().Length == 1 && m.GetParameters().Length == 1 && m.GetParameters()[0].ParameterType.IsGenericType && !m.GetParameters()[0].ParameterType.IsGenericParameter)).MakeGenericMethod(typeof(global::ExpressiveSharp.Docs.PlaygroundModel.Webshop.Order)), new global::System.Linq.Expressions.Expression[] { expr_5 });
            var expr_6 = global::System.Linq.Expressions.Expression.Constant(10, typeof(int)); // 10
            var expr_3 = global::System.Linq.Expressions.Expression.MakeBinary(global::System.Linq.Expressions.ExpressionType.GreaterThanOrEqual, expr_4, expr_6);
            var expr_7 = global::System.Linq.Expressions.Expression.Constant("Gold", typeof(string)); // "Gold"
            var expr_8 = global::System.Linq.Expressions.Expression.Constant("Standard", typeof(string)); // "Standard"
            var expr_2 = global::System.Linq.Expressions.Expression.Condition(expr_3, expr_7, expr_8, typeof(string));
            var expr_9 = global::System.Linq.Expressions.Expression.Bind(typeof(global::ExpressiveSharp.Docs.Playground.Snippet.CustomerDetailDto).GetProperty("Email", global::System.Reflection.BindingFlags.Public | global::System.Reflection.BindingFlags.NonPublic | global::System.Reflection.BindingFlags.Instance), expr_1);
            var expr_10 = global::System.Linq.Expressions.Expression.Bind(typeof(global::ExpressiveSharp.Docs.Playground.Snippet.CustomerDetailDto).GetProperty("Tier", global::System.Reflection.BindingFlags.Public | global::System.Reflection.BindingFlags.NonPublic | global::System.Reflection.BindingFlags.Instance), expr_2);
            var expr_11 = global::System.Linq.Expressions.Expression.MemberInit(expr_0, expr_9, expr_10);
            return global::System.Linq.Expressions.Expression.Lambda<global::System.Func<global::ExpressiveSharp.Docs.PlaygroundModel.Webshop.Customer, global::ExpressiveSharp.Docs.Playground.Snippet.CustomerDetailDto>>(expr_11, p_c);
        }
    }
}


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

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


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

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


// === 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.CustomerDto).GetConstructor(allFlags, null, new global::System.Type[] { typeof(global::ExpressiveSharp.Docs.PlaygroundModel.Webshop.Customer) }, null), "ExpressiveSharp.Generated.ExpressiveSharp_Docs_Playground_Snippet_CustomerDto", "_ctor_P0_ExpressiveSharp_Docs_PlaygroundModel_Webshop_Customer_Expression");
            Register(map, typeof(global::ExpressiveSharp.Docs.Playground.Snippet.CustomerDetailDto).GetConstructor(allFlags, null, new global::System.Type[] { typeof(global::ExpressiveSharp.Docs.PlaygroundModel.Webshop.Customer) }, null), "ExpressiveSharp.Generated.ExpressiveSharp_Docs_Playground_Snippet_CustomerDetailDto", "_ctor_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, "ZR/mGl+fdK/+9lBu5lPkI4IBAABfX1NuaXBwZXQuY3M=")]
        internal static global::ExpressiveSharp.IExpressiveQueryable<global::ExpressiveSharp.Docs.Playground.Snippet.CustomerDetailDto> __Polyfill_Select_3e61_14_24(
            this global::ExpressiveSharp.IExpressiveQueryable<global::ExpressiveSharp.Docs.PlaygroundModel.Webshop.Customer> source,
            global::System.Func<global::ExpressiveSharp.Docs.PlaygroundModel.Webshop.Customer, global::ExpressiveSharp.Docs.Playground.Snippet.CustomerDetailDto> __func)
        {
            // Source: c => new CustomerDetailDto(c)
            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.New(typeof(global::ExpressiveSharp.Docs.Playground.Snippet.CustomerDetailDto).GetConstructor(global::System.Reflection.BindingFlags.Public | global::System.Reflection.BindingFlags.NonPublic | global::System.Reflection.BindingFlags.Instance, null, new global::System.Type[] { typeof(global::ExpressiveSharp.Docs.PlaygroundModel.Webshop.Customer) }, null), i3e6114c24_p_c); // new CustomerDetailDto(c)
            var __lambda = global::System.Linq.Expressions.Expression.Lambda<global::System.Func<global::ExpressiveSharp.Docs.PlaygroundModel.Webshop.Customer, global::ExpressiveSharp.Docs.Playground.Snippet.CustomerDetailDto>>(i3e6114c24_expr_0, i3e6114c24_p_c);
            return global::ExpressiveSharp.ExpressiveQueryableExtensions.AsExpressive(
                global::System.Linq.Queryable.Select(
                    (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 →

The generated expression inlines both the base constructor and the derived constructor body:

csharp
(Customer c) => new CustomerDetailDto()
{
    Id = c.Id,
    Name = c.Name,
    Email = c.Email,
    Tier = c.Orders.Count() >= 10 ? "Gold" : "Standard"
}

Constructor Overloads ​

Multiple [Expressive] constructors per class are supported -- each overload generates its own expression, distinguished by parameter types:

csharp
public class OrderDto
{
    public int Id { get; set; }
    public decimal Total { get; set; }
    public string? Note { get; set; }

    public OrderDto() { }

    [Expressive]
    public OrderDto(int id, decimal total)
    {
        Id = id;
        Total = total;
    }

    [Expressive]
    public OrderDto(int id, decimal total, string note)
    {
        Id = id;
        Total = total;
        Note = note;
    }
}

Factory Method Conversion ​

If you have an existing [Expressive] factory method that returns new T { ... }, the generator emits diagnostic EXP0012 (Info severity) suggesting a conversion to a constructor.

Diagnostics ​

CodeSeverityDescription
EXP0002ErrorClass is missing a parameterless constructor
EXP0003ErrorDelegated constructor source not available (base/this chain cannot be analyzed)
EXP0012InfoFactory method can be converted to an [Expressive] constructor

Next Steps ​

Released under the MIT License.

Copyright © ExpressiveSharp Contributors