Update DynamicGetMemberBinder to add BindingRestrictions to DynamicMetaObject

Author: StefH

src-console/ConsoleApp_net6.0/Program.cs

@@ -83,14 +83,14 @@ private static void Q912()
         // GROUPING SET 1: (Region, Product)
         var detailed = rows
             .GroupBy("new (Region, Product)")
-            .Select<GroupedSalesData>("new (Key.Region as Region, Key.Product as Product, Sum(Convert.ToInt32(Sales)) as TotalSales, 0 as GroupLevel)");
+            .Select("new (Key.Region as Region, Key.Product as Product, Sum(Convert.ToInt32(Sales)) as TotalSales, 0 as GroupLevel)");
 
         // GROUPING SET 2: (Region)
         var regionSubtotal = rows
             .GroupBy("Region")
-            .Select<GroupedSalesData>("new (Key as Region, null as Product, Sum(Convert.ToInt32(Sales)) as TotalSales, 1 as GroupLevel)");
+            .Select("new (Key as Region, null as Product, Sum(Convert.ToInt32(Sales)) as TotalSales, 1 as GroupLevel)");
 
-        var combined = detailed.Concat(regionSubtotal);
+        var combined = detailed.ToDynamicArray().Concat(regionSubtotal.ToDynamicArray()).AsQueryable();
         var ordered = combined.OrderBy("Product").ToDynamicList();
 
         int x = 9;

src/System.Linq.Dynamic.Core/DynamicGetMemberBinder.cs

@@ -21,13 +21,15 @@ public DynamicGetMemberBinder(string name, ParsingConfig? config) : base(name, c
 
     public override DynamicMetaObject FallbackGetMember(DynamicMetaObject target, DynamicMetaObject? errorSuggestion)
     {
-        var instance = Expression.Call(
+        var methodCallExpression = Expression.Call(
             DynamicGetMemberMethod,
             target.Expression,
             Expression.Constant(Name),
             Expression.Constant(IgnoreCase));
 
-        return DynamicMetaObject.Create(target.Value!, instance);
+        // Fix #907 and #912: "The result of the dynamic binding produced by the object with type '<>f__AnonymousType1`4' for the binder 'System.Linq.Dynamic.Core.DynamicGetMemberBinder' needs at least one restriction.".
+        var restrictions = BindingRestrictions.GetInstanceRestriction(target.Expression, target.Value);
+        return new DynamicMetaObject(methodCallExpression, restrictions, target.Value!);
     }
 
     public static object? GetDynamicMember(object value, string name, bool ignoreCase)

test/System.Linq.Dynamic.Core.Tests/DynamicGetMemberBinderTests.cs

@@ -0,0 +1,64 @@
+using FluentAssertions;
+using Xunit;
+
+namespace System.Linq.Dynamic.Core.Tests;
+
+public class DynamicGetMemberBinderTests
+{
+    public class SalesData
+    {
+        public string Region { get; set; } = null!;
+
+        public string Product { get; set; } = null!;
+
+        public string Sales { get; set; } = null!;
+    }
+
+    [Fact]
+    public void DynamicGetMemberBinder_Test1()
+    {
+        // Arrange
+        var rows = new SalesData[]
+        {
+            new() { Region = "North", Product = "Widget", Sales = "100" },
+            new() { Region = "North", Product = "Gadget", Sales = "150" },
+            new() { Region = "South", Product = "Widget", Sales = "200" },
+            new() { Region = "South", Product = "Gadget", Sales = "100" },
+            new() { Region = "North", Product = "Widget", Sales = "50" }
+        }.AsQueryable();
+
+        // Act
+        var grouping1 = rows
+            .GroupBy("new (Region, Product)")
+            .Select("new (Key.Region as Region, Key.Product as Product, Sum(Convert.ToInt32(Sales)) as TotalSales, 0 as GroupLevel)");
+
+        var grouping2 = rows
+            .GroupBy("Region")
+            .Select("new (Key as Region, null as Product, Sum(Convert.ToInt32(Sales)) as TotalSales, 1 as GroupLevel)");
+
+        var combined = grouping1.ToDynamicArray().Concat(grouping2.ToDynamicArray()).AsQueryable();
+        var ordered = combined.OrderBy("Product").ToDynamicList();
+
+        // Assert
+        ordered.Should().HaveCount(6);
+    }
+
+    [Fact]
+    public void DynamicGetMemberBinder_Test2()
+    {
+        // Arrange
+        var dynamicData = new[] { 1, 2 }
+            .AsQueryable()
+            .Select("new { it as Value }")
+            .ToDynamicArray();
+
+        // Act
+        var dynamicResult = dynamicData
+            .AsQueryable()
+            .Select("Value")
+            .ToDynamicArray();
+
+        // Assert
+        dynamicResult.Should().HaveCount(2);
+    }
+}