Add IndexerName attribute to DynamicClass to fix naming issues with Item

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

@@ -2,6 +2,7 @@
 using System.Collections.Generic;
 using System.Dynamic;
 using System.Reflection;
+using System.Runtime.CompilerServices;
 
 namespace System.Linq.Dynamic.Core;
 
@@ -18,6 +19,8 @@ namespace System.Linq.Dynamic.Core;
 /// </summary>
 public abstract class DynamicClass : DynamicObject
 {
+    internal const string IndexerName = "System_Linq_Dynamic_Core_DynamicClass_Indexer";
+
     private Dictionary<string, object?>? _propertiesDictionary;
 
     private Dictionary<string, object?> Properties
@@ -99,11 +102,12 @@ public void SetDynamicPropertyValue(string propertyName, object value)
     /// <value>The <see cref="object"/>.</value>
     /// <param name="name">The name.</param>
     /// <returns>Value from the property.</returns>
+    [IndexerName(IndexerName)]
     public object? this[string name]
     {
         get
         {
-            return Properties.TryGetValue(name, out object? result) ? result : null;
+            return Properties.TryGetValue(name, out var result) ? result : null;
         }
 
         set
@@ -153,7 +157,7 @@ public override bool TryGetMember(GetMemberBinder binder, out object? result)
     /// </returns>
     public override bool TrySetMember(SetMemberBinder binder, object? value)
     {
-        string name = binder.Name;
+        var name = binder.Name;
         if (Properties.ContainsKey(name))
         {
             Properties[name] = value;

src/System.Linq.Dynamic.Core/DynamicClass.net35.cs

@@ -6,6 +6,8 @@ namespace System.Linq.Dynamic.Core;
 /// </summary>
 public abstract class DynamicClass
 {
+    internal const string IndexerName = "System_Linq_Dynamic_Core_DynamicClass_Indexer";
+
     /// <summary>
     /// Gets the dynamic property by name.
     /// </summary>

src/System.Linq.Dynamic.Core/DynamicClass.uap.cs

@@ -1,6 +1,7 @@
 #if UAP10_0
 using System.Collections.Generic;
 using System.Dynamic;
+using System.Runtime.CompilerServices;
 
 namespace System.Linq.Dynamic.Core;
 
@@ -9,6 +10,8 @@ namespace System.Linq.Dynamic.Core;
 /// </summary>
 public class DynamicClass : DynamicObject
 {
+    internal const string IndexerName = "System_Linq_Dynamic_Core_DynamicClass_Indexer";
+
     private readonly Dictionary<string, object> _properties = new();
 
     /// <summary>
@@ -31,6 +34,7 @@ public DynamicClass(params KeyValuePair<string, object>[] propertylist)
     /// </value>
     /// <param name="name">The name.</param>
     /// <returns>Value from the property.</returns>
+    [IndexerName(IndexerName)]
     public object this[string name]
     {
         get

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

@@ -66,7 +66,7 @@
             ParameterExpression parameter = ParameterExpressionHelper.CreateParameterExpression(source.ElementType, "s");
             Expression selector = Expression.Lambda(Expression.MakeMemberAccess(parameter, property), parameter);
             // We've tried to find an expression of the type Expression<Func<TSource, TAcc>>,
             // which is expressed as ( (TSource s) => s.Price );
 
             var methods = typeof(Queryable).GetMethods().Where(x => x.Name == function && x.IsGenericMethod).ToArray();
 
@@ -2135,7 +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
@@ -2849,7 +2849,7 @@
 
         private static LambdaExpression EnsureLambdaExpressionReturnsObject(LambdaExpression lambdaExpression)
         {
-            if (!lambdaExpression.GetReturnType().GetTypeInfo().IsSubclassOf(typeof(DynamicClass)))
+            if (!TypeHelper.IsDynamicClass(lambdaExpression.GetReturnType()))
             {
                 return Expression.Lambda(Expression.Convert(lambdaExpression.Body, typeof(object)), lambdaExpression.Parameters.ToArray());
             }

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

@@ -1580,7 +1580,7 @@
         var propertyInfos = type.GetProperties();
         if (type.GetTypeInfo().BaseType == typeof(DynamicClass))
         {
-            propertyInfos = propertyInfos.Where(x => x.Name != "Item").ToArray();
+            propertyInfos = propertyInfos.Where(x => x.Name != DynamicClass.IndexerName).ToArray();
         }
 
         var propertyTypes = propertyInfos.Select(p => p.PropertyType).ToArray();
@@ -1906,7 +1906,7 @@
 #if UAP10_0 || NETSTANDARD1_3
         if (type == typeof(DynamicClass))
         {
-            return Expression.MakeIndex(expression, typeof(DynamicClass).GetProperty("Item"), new[] { Expression.Constant(id) });
+            return Expression.MakeIndex(expression!, typeof(DynamicClass).GetProperty(DynamicClass.IndexerName), [Expression.Constant(id)]);
         }
 #endif
         if (TryFindPropertyOrField(type!, id, expression, out var propertyOrFieldExpression))
@@ -1920,7 +1920,8 @@
 
         if (!_parsingConfig.DisableMemberAccessToIndexAccessorFallback && extraCheck)
         {
-            var indexerMethod = expression?.Type.GetMethod("get_Item", new[] { typeof(string) });
+            var indexerName = TypeHelper.IsDynamicClass(type!) ? DynamicClass.IndexerName : "Item";
+            var indexerMethod = expression?.Type.GetMethod($"get_{indexerName}", [typeof(string)]);
             if (indexerMethod != null)
             {
                 return Expression.Call(expression, indexerMethod, Expression.Constant(id));
@@ -1954,8 +1955,8 @@
         switch (member)
         {
             case PropertyInfo property:
                 var propertyIsStatic = property?.GetGetMethod().IsStatic ?? property?.GetSetMethod().IsStatic ?? false;
                 propertyOrFieldExpression = propertyIsStatic ? Expression.Property(null, property) : Expression.Property(expression, property);
                 return true;
 
             case FieldInfo field:

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

@@ -6,6 +6,11 @@ namespace System.Linq.Dynamic.Core.Parser;
 
 internal static class TypeHelper
 {
+    internal static bool IsDynamicClass(Type type)
+    {
+        return type == typeof(DynamicClass) || type.GetTypeInfo().IsSubclassOf(typeof(DynamicClass));
+    }
+
     internal static bool TryGetAsEnumerable(Type type, [NotNullWhen(true)] out Type? enumerableType)
     {
         if (type.IsArray)

test/System.Linq.Dynamic.Core.Tests/EntitiesTests.Select.cs

@@ -164,4 +164,15 @@ public void Entities_Select_DynamicClass_And_Select_DynamicClass()
 
         dynamicResult.Should().BeEquivalentTo([1000, 1001]);
     }
+
+    [Fact]
+    public void Entities_Select_ClassWithItemProperty()
+    {
+        // Act
+        var result = _context.Posts.Select(x => new { x.Item, x.BlogId }).ToArray();
+        var resultDynamic = _context.Posts.Select("new (Item, BlogId)").ToDynamicArray();
+
+        // Assert
+        resultDynamic.Should().BeEquivalentTo(result);
+    }
 }

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

@@ -11,7 +11,7 @@ namespace System.Linq.Dynamic.Core.Tests;
 
 public partial class EntitiesTests : IClassFixture<EntitiesTestsDatabaseFixture>
 {
-    private static readonly Random Rnd = new Random(1);
+    private static readonly Random Rnd = new(1);
 
     private readonly BlogContext _context;
 
@@ -66,7 +66,8 @@ private void InternalPopulateTestData()
                     Content = "My Content",
                     PostDate = postDate,
                     CloseDate = Rnd.Next(0, 10) < 5 ? postDate.AddDays(1) : null,
-                    NumberOfReads = Rnd.Next(0, 5000)
+                    NumberOfReads = Rnd.Next(0, 5000),
+                    Item = "Item " + Rnd.Next(0, 1000)
                 };
 
                 _context.Posts.Add(post);

test/System.Linq.Dynamic.Core.Tests/Helpers/Entities/Post.cs

@@ -22,4 +22,6 @@ public class Post
     public DateTime PostDate { get; set; }
 
     public DateTime? CloseDate { get; set; }
+
+    public string? Item { get; set; }
 }

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

@@ -20,6 +20,14 @@ namespace System.Linq.Dynamic.Core.Tests
 {
     public partial class QueryableTests
     {
+        [DynamicLinqType]
+        public class ClassWithItem
+        {
+            public string? Item { get; set; }
+
+            public int Value { get; set; }
+        }
+
         [DynamicLinqType]
         public class Example
         {
@@ -536,5 +544,24 @@ public void Select_Dynamic_StringConcatDifferentTypes(string expression, string
             // Act
             queryable.Select(config, expression).ToDynamicArray<string>()[0].Should().Be(expectedResult);
         }
+
+        [Fact]
+        public void Select_Dynamic_ClassWithItemProperty()
+        {
+            // Arrange
+            var data = new []
+            {
+                new ClassWithItem { Item = "Value1", Value = 1 },
+                new ClassWithItem { Item = "Value2", Value = 2 }
+            };
+            var queryable = data.AsQueryable();
+
+            // Act
+            var result = queryable.Select(x => new {x.Item, x.Value }).ToArray();
+            var resultDynamic = queryable.Select("new (Item, Value)").ToDynamicArray();
+
+            // Assert
+            resultDynamic.Should().BeEquivalentTo(result);
+        }
     }
 }