Fix GroupByMany using composite key and normal key

README.md

@@ -84,7 +84,7 @@ Or provide a list of additional types in the [DefaultDynamicLinqCustomTypeProvid
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src/System.Linq.Dynamic.Core/DynamicQueryableExtensions.cs

@@ -871,12 +871,10 @@
             Check.HasNoNulls(keySelectors);
 
             var selectors = new List<Func<TElement, object>>(keySelectors.Length);
-
-            bool createParameterCtor = true;
             foreach (var selector in keySelectors)
             {
-                LambdaExpression l = DynamicExpressionParser.ParseLambda(config, createParameterCtor, typeof(TElement), typeof(object), selector);
-                selectors.Add((Func<TElement, object>)l.Compile());
+                var lambdaExpression = DynamicExpressionParser.ParseLambda(config, createParameterCtor: true, typeof(TElement), null, selector);
+                selectors.Add((Func<TElement, object>)EnsureLambdaExpressionReturnsObject(lambdaExpression).Compile());
             }
 
             return GroupByManyInternal(source, selectors.ToArray(), 0);
@@ -913,8 +911,9 @@
 
             var selector = keySelectors[currentSelector];
 
-            var result = source.GroupBy(selector).Select(
-                g => new GroupResult
+            var result = source
+                .GroupBy(selector)
+                .Select(g => new GroupResult
                 {
                     Key = g.Key,
                     Count = g.Count(),
@@ -2136,7 +2135,7 @@
         /// <inheritdoc cref="SelectMany(IQueryable, ParsingConfig, string, string, string, string, object[], object[])"/>
         public static IQueryable SelectMany(this IQueryable source, string collectionSelector, string resultSelector, string collectionParameterName, string resultParameterName, object?[]? collectionSelectorArgs = null, params object?[]? resultSelectorArgs)
         {
             return SelectMany(source, ParsingConfig.Default, collectionSelector, resultSelector, collectionParameterName, resultParameterName, collectionSelectorArgs, resultSelectorArgs);
         }
 
         #endregion SelectMany
@@ -2847,6 +2846,16 @@
 
             return (TResult?)Convert.ChangeType(result, typeof(TResult))!;
         }
+
+        private static LambdaExpression EnsureLambdaExpressionReturnsObject(LambdaExpression lambdaExpression)
+        {
+            if (!lambdaExpression.GetReturnType().GetTypeInfo().IsSubclassOf(typeof(DynamicClass)))
+            {
+                return Expression.Lambda(Expression.Convert(lambdaExpression.Body, typeof(object)), lambdaExpression.Parameters.ToArray());
+            }
+
+            return lambdaExpression;
+        }
         #endregion Private Helpers
     }
 }

src/System.Linq.Dynamic.Core/Parser/ExpressionHelper.cs

@@ -45,15 +45,15 @@ public bool TryUnwrapAsConstantExpression<TValue>(Expression? expression, [NotNu
             return true;
         }
 
-        value = default;
+        value = null;
         return false;
     }
 
     public bool TryUnwrapAsConstantExpression(Expression? expression, [NotNullWhen(true)] out ConstantExpression? value)
     {
         if (!_parsingConfig.UseParameterizedNamesInDynamicQuery || expression is not MemberExpression memberExpression)
         {
-            value = default;
+            value = null;
             return false;
         }
 
@@ -68,7 +68,7 @@ public bool TryUnwrapAsConstantExpression(Expression? expression, [NotNullWhen(t
             return true;
         }
 
-        value = default;
+        value = null;
         return false;
     }
 
@@ -531,6 +531,6 @@ private static object[] ConvertIfIEnumerableHasValues(IEnumerable? input)
             return input.Cast<object>().ToArray();
         }
 
-        return new object[0];
+        return [];
     }
 }

test/System.Linq.Dynamic.Core.Tests/QueryableTests.GroupByMany.cs

@@ -1,57 +1,82 @@
 using System.Collections.Generic;
+using FluentAssertions;
 using NFluent;
 using Xunit;
 
-namespace System.Linq.Dynamic.Core.Tests
+namespace System.Linq.Dynamic.Core.Tests;
+
+public partial class QueryableTests
 {
-    public partial class QueryableTests
+    [Fact]
+    public void GroupByMany_Dynamic_LambdaExpressions()
+    {
+        var lst = new List<Tuple<int, int, int>>
+        {
+            new(1, 1, 1),
+            new(1, 1, 2),
+            new(1, 1, 3),
+            new(2, 2, 4),
+            new(2, 2, 5),
+            new(2, 2, 6),
+            new(2, 3, 7)
+        };
+
+        var sel = lst.GroupByMany(x => x.Item1, x => x.Item2).ToArray();
+
+        Assert.Equal(2, sel.Length);
+        Assert.Single(sel.First().Subgroups);
+        Assert.Equal(2, sel.Skip(1).First().Subgroups.Count());
+    }
+
+    [Fact]
+    public void GroupByMany_Dynamic_StringExpressions()
     {
-        [Fact]
-        public void GroupByMany_Dynamic_LambdaExpressions()
+        var lst = new List<Tuple<int, int, int>>
         {
-            var lst = new List<Tuple<int, int, int>>
-            {
-                new Tuple<int, int, int>(1, 1, 1),
-                new Tuple<int, int, int>(1, 1, 2),
-                new Tuple<int, int, int>(1, 1, 3),
-                new Tuple<int, int, int>(2, 2, 4),
-                new Tuple<int, int, int>(2, 2, 5),
-                new Tuple<int, int, int>(2, 2, 6),
-                new Tuple<int, int, int>(2, 3, 7)
-            };
-
-            var sel = lst.AsQueryable().GroupByMany(x => x.Item1, x => x.Item2);
-
-            Assert.Equal(2, sel.Count());
-            Assert.Single(sel.First().Subgroups);
-            Assert.Equal(2, sel.Skip(1).First().Subgroups.Count());
-        }
-
-        [Fact]
-        public void GroupByMany_Dynamic_StringExpressions()
+            new(1, 1, 1),
+            new(1, 1, 2),
+            new(1, 1, 3),
+            new(2, 2, 4),
+            new(2, 2, 5),
+            new(2, 2, 6),
+            new(2, 3, 7)
+        };
+
+        var sel = lst.GroupByMany("Item1", "Item2").ToList();
+
+        Check.That(sel.Count).Equals(2);
+
+        var firstGroupResult = sel.First();
+        Check.That(firstGroupResult.ToString()).Equals("1 (3)");
+        Check.That(firstGroupResult.Subgroups.Count()).Equals(1);
+
+        var skippedGroupResult = sel.Skip(1).First();
+        Check.That(skippedGroupResult.ToString()).Equals("2 (4)");
+        Check.That(skippedGroupResult.Subgroups.Count()).Equals(2);
+    }
+
+    [Fact]
+    public void GroupByMany_Dynamic_CompositeKey()
+    {
+        // Arrange
+        var data = new[]
         {
-            var lst = new List<Tuple<int, int, int>>
-            {
-                new Tuple<int, int, int>(1, 1, 1),
-                new Tuple<int, int, int>(1, 1, 2),
-                new Tuple<int, int, int>(1, 1, 3),
-                new Tuple<int, int, int>(2, 2, 4),
-                new Tuple<int, int, int>(2, 2, 5),
-                new Tuple<int, int, int>(2, 2, 6),
-                new Tuple<int, int, int>(2, 3, 7)
-            };
-
-            var sel = lst.AsQueryable().GroupByMany("Item1", "Item2").ToList();
-
-            Check.That(sel.Count).Equals(2);
-
-            var firstGroupResult = sel.First();
-            Check.That(firstGroupResult.ToString()).Equals("1 (3)");
-            Check.That(firstGroupResult.Subgroups.Count()).Equals(1);
-
-            var skippedGroupResult = sel.Skip(1).First();
-            Check.That(skippedGroupResult.ToString()).Equals("2 (4)");
-            Check.That(skippedGroupResult.Subgroups.Count()).Equals(2);
-        }
+            new { MachineId = 1, Machine = new { Id = 1, Name = "A" } },
+            new { MachineId = 1, Machine = new { Id = 1, Name = "A" } },
+            new { MachineId = 2, Machine = new { Id = 2, Name = "B" } }
+        };
+
+        // Act
+        var normalResult = data
+            .GroupByMany(d => new { d.MachineId, d.Machine.Name }, a => a.Machine.Id)
+            .Select(x => x.ToString())
+            .ToList();
+        var result = data
+            .GroupByMany("new (MachineId, Machine.Name)", "Machine.Id")
+            .Select(x => x.ToString())
+            .ToList();
+
+        // Assert
+        result.Should().BeEquivalentTo(normalResult);
     }
-}
+}