From b62479733060cebd604ebd372dd91dc1c2762cdc Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?David=20Leb=C3=A9e?= <DavidLebee@roxboro.biz>
Date: Sun, 11 Mar 2018 21:54:13 -0500
Subject: [PATCH] create anonymous type and group by it. :)

---
 .../Helpers/QueryableHelpers.cs               |  6 +++--
 .../Helpers/TypeHelpers.cs                    | 24 +++++++++++++++++++
 2 files changed, 28 insertions(+), 2 deletions(-)

diff --git a/PoweredSoft.DynamicLinq/Helpers/QueryableHelpers.cs b/PoweredSoft.DynamicLinq/Helpers/QueryableHelpers.cs
index 57fac38..698e296 100644
--- a/PoweredSoft.DynamicLinq/Helpers/QueryableHelpers.cs
+++ b/PoweredSoft.DynamicLinq/Helpers/QueryableHelpers.cs
@@ -99,8 +99,10 @@ namespace PoweredSoft.DynamicLinq.Helpers
             var constructor = anonymousType.GetConstructor(constructorTypes);
             var newExpression = Expression.New(constructor, partExpressions);
             var genericMethod = Constants.GroupByMethod.MakeGenericMethod(type, anonymousType);
-
-            return query;
+            var lambda = Expression.Lambda(newExpression, parameter);
+            var groupByExpression = Expression.Call(genericMethod, query.Expression, lambda);
+            var result = query.Provider.CreateQuery(groupByExpression);
+            return result;
         }
 
         public static IQueryable GroupBy(IQueryable query, Type type, string path)
diff --git a/PoweredSoft.DynamicLinq/Helpers/TypeHelpers.cs b/PoweredSoft.DynamicLinq/Helpers/TypeHelpers.cs
index 2a7bb2a..334f602 100644
--- a/PoweredSoft.DynamicLinq/Helpers/TypeHelpers.cs
+++ b/PoweredSoft.DynamicLinq/Helpers/TypeHelpers.cs
@@ -50,10 +50,34 @@ namespace PoweredSoft.DynamicLinq.Helpers
             {
                 CreatePropertyOnType(dynamicType, field.name, field.type);
             });
+            CreateConstructorWithAllPropsOnType(dynamicType, fields);
             var ret = dynamicType.CreateTypeInfo();
             return ret;
         }
 
+        private static void CreateConstructorWithAllPropsOnType(TypeBuilder dynamicType, List<(Type type, string name)> fields)
+        {
+            var ctor = dynamicType.DefineConstructor(MethodAttributes.Public, CallingConventions.Standard, fields.Select(t => t.type).ToArray());
+            var parameters = fields
+                .Select((field, i) =>
+               {
+                   return ctor.DefineParameter(i++, ParameterAttributes.None, $"{field.name}_1");
+               })
+               .ToList();
+
+            var emitter = ctor.GetILGenerator();
+            emitter.Emit(OpCodes.Nop);
+
+            // Load `this` and call base constructor with arguments
+            emitter.Emit(OpCodes.Ldarg_0);
+            for (var i = 1; i <= parameters.Count; ++i)
+            {
+                emitter.Emit(OpCodes.Ldarg, i);
+            }
+            emitter.Emit(OpCodes.Call, ctor);
+            emitter.Emit(OpCodes.Ret);
+        }
+
         internal static void CreatePropertyOnType(TypeBuilder typeBuilder, string propertyName, Type propertyType)
         {
             // Generate a property called "Name"