Distinct

src/System.Linq.Dynamic.Core.NewtonsoftJson/NewtonsoftJsonExtensions.cs

@@ -281,6 +281,50 @@ public static int Count(this JArray source, LambdaExpression lambda)
     }
     #endregion Count
 
+    #region DefaultIfEmpty
+    /// <summary>
+    /// Returns the elements of the specified sequence or the type parameter's default value in a singleton collection if the sequence is empty.
+    /// </summary>
+    /// <param name="source">The <see cref="JArray"/> to return a default value for if empty.</param>
+    /// <returns>An <see cref="JArray"/> that contains default if source is empty; otherwise, source.</returns>
+    public static JArray DefaultIfEmpty(this JArray source)
+    {
+        Check.NotNull(source);
+
+        var queryable = ToQueryable(source);
+        return ToJArray(queryable.DefaultIfEmpty);
+    }
+
+    /// <summary>
+    /// Returns the elements of the specified sequence or the type parameter's default value in a singleton collection if the sequence is empty.
+    /// </summary>
+    /// <param name="source">The <see cref="JArray"/> to return a default value for if empty.</param>
+    /// <param name="defaultValue">The value to return if the sequence is empty.</param>
+    /// <returns>An <see cref="JArray"/> that contains defaultValue if source is empty; otherwise, source.</returns>
+    public static JArray DefaultIfEmpty(this JArray source, object? defaultValue)
+    {
+        Check.NotNull(source);
+
+        var queryable = ToQueryable(source);
+        return ToJArray(() => queryable.DefaultIfEmpty(defaultValue));
+    }
+    #endregion
+
+    #region Distinct
+    /// <summary>
+    /// Returns distinct elements from a sequence by using the default equality comparer to compare values.
+    /// </summary>
+    /// <param name="source">The sequence to remove duplicate elements from.</param>
+    /// <returns>An <see cref="JArray"/> that contains distinct elements from the source sequence.</returns>
+    public static JArray Distinct(this JArray source)
+    {
+        Check.NotNull(source);
+
+        var queryable = ToQueryable(source);
+        return ToJArray(queryable.Distinct);
+    }
+    #endregion Distinct
+
     #region Select
     /// <summary>
     /// Projects each element of a sequence into a new form.

src/System.Linq.Dynamic.Core.SystemTextJson/SystemTextJsonExtensions.cs

@@ -282,6 +282,50 @@ public static int Count(this JsonDocument source, LambdaExpression lambda)
     }
     #endregion Count
 
+    #region DefaultIfEmpty
+    /// <summary>
+    /// Returns the elements of the specified sequence or the type parameter's default value in a singleton collection if the sequence is empty.
+    /// </summary>
+    /// <param name="source">The <see cref="JsonDocument"/> to return a default value for if empty.</param>
+    /// <returns>An <see cref="JsonDocument"/> that contains default if source is empty; otherwise, source.</returns>
+    public static JsonDocument DefaultIfEmpty(this JsonDocument source)
+    {
+        Check.NotNull(source);
+
+        var queryable = ToQueryable(source);
+        return ToJsonDocumentArray(queryable.DefaultIfEmpty);
+    }
+
+    /// <summary>
+    /// Returns the elements of the specified sequence or the type parameter's default value in a singleton collection if the sequence is empty.
+    /// </summary>
+    /// <param name="source">The <see cref="JsonDocument"/> to return a default value for if empty.</param>
+    /// <param name="defaultValue">The value to return if the sequence is empty.</param>
+    /// <returns>An <see cref="JsonDocument"/> that contains defaultValue if source is empty; otherwise, source.</returns>
+    public static JsonDocument DefaultIfEmpty(this JsonDocument source, object? defaultValue)
+    {
+        Check.NotNull(source);
+
+        var queryable = ToQueryable(source);
+        return ToJsonDocumentArray(() => queryable.DefaultIfEmpty(defaultValue));
+    }
+    #endregion
+
+    #region Distinct
+    /// <summary>
+    /// Returns distinct elements from a sequence by using the default equality comparer to compare values.
+    /// </summary>
+    /// <param name="source">The sequence to remove duplicate elements from.</param>
+    /// <returns>An <see cref="JsonDocument"/> that contains distinct elements from the source sequence.</returns>
+    public static JsonDocument Distinct(this JsonDocument source)
+    {
+        Check.NotNull(source);
+
+        var queryable = ToQueryable(source);
+        return ToJsonDocumentArray(queryable.Distinct);
+    }
+    #endregion Distinct
+
     #region Select
     /// <summary>
     /// Projects each element of a sequence into a new form.
@@ -352,17 +396,7 @@ private static JsonDocument ToJsonDocumentArray(Func<IQueryable> func)
         var array = new List<object>();
         foreach (var dynamicElement in func())
         {
-            object element;
-            if (dynamicElement is DynamicClass dynamicClass)
-            {
-                element = JsonElementUtils.FromObject(dynamicClass);
-            }
-            else
-            {
-                element = dynamicElement;
-            }
-
-            //var element = dynamicElement is DynamicClass dynamicClass ? JsonElementUtils.FromObject(dynamicClass) : dynamicElement;
+            var element = dynamicElement is DynamicClass dynamicClass ? JsonElementUtils.FromObject(dynamicClass) : dynamicElement;
             array.Add(element);
         }
 

test/System.Linq.Dynamic.Core.NewtonsoftJson.Tests/NewtonsoftJsonTests.cs

@@ -93,6 +93,29 @@ public void Count()
         result2.Should().Be(1);
     }
 
+    [Fact]
+    public void Distinct()
+    {
+        var json = @"[
+            {
+                ""Name"": ""John""
+            },
+            {
+                ""Name"": ""Doe""
+            },
+            {
+                ""Name"": ""John""
+            }
+        ]";
+        var source = JArray.Parse(json);
+
+        // Act
+        var result = source.Select("Name").Distinct();
+
+        // Assert
+        result.Should().HaveCount(2);
+    }
+
     [Fact]
     public void Select()
     {

test/System.Linq.Dynamic.Core.SystemTextJson.Tests/SystemTextJsonTests.cs

@@ -93,6 +93,29 @@ public void Count()
         result2.Should().Be(1);
     }
 
+    [Fact]
+    public void Distinct()
+    {
+        var json = @"[
+            {
+                ""Name"": ""John""
+            },
+            {
+                ""Name"": ""Doe""
+            },
+            {
+                ""Name"": ""John""
+            }
+        ]";
+        var source = JsonDocument.Parse(json);
+
+        // Act
+        var result = source.Select("Name").Distinct();
+
+        // Assert
+        result.RootElement.EnumerateArray().Should().HaveCount(2);
+    }
+
     [Fact]
     public void Select()
     {