Add Try methods to JsonObject

src/libraries/System.Text.Json/ref/System.Text.Json.cs

@@ -842,6 +842,8 @@ public sealed partial class JsonObject : System.Text.Json.Nodes.JsonNode, System
         System.Collections.Generic.KeyValuePair<string, System.Text.Json.Nodes.JsonNode?> System.Collections.Generic.IList<System.Collections.Generic.KeyValuePair<string, System.Text.Json.Nodes.JsonNode?>>.this[int index] { get { throw null; } set { } }
         public void Add(System.Collections.Generic.KeyValuePair<string, System.Text.Json.Nodes.JsonNode?> property) { }
         public void Add(string propertyName, System.Text.Json.Nodes.JsonNode? value) { }
+        public bool TryAdd(string propertyName, JsonNode? value) { throw null; }
+        public bool TryAdd(string propertyName, JsonNode? value, out int index) { throw null; }
         public void Clear() { }
         public bool ContainsKey(string propertyName) { throw null; }
         public static System.Text.Json.Nodes.JsonObject? Create(System.Text.Json.JsonElement element, System.Text.Json.Nodes.JsonNodeOptions? options = default(System.Text.Json.Nodes.JsonNodeOptions?)) { throw null; }
@@ -862,6 +864,7 @@ public void SetAt(int index, System.Text.Json.Nodes.JsonNode? value) { }
         void System.Collections.Generic.IList<System.Collections.Generic.KeyValuePair<string, System.Text.Json.Nodes.JsonNode?>>.RemoveAt(int index) { }
         System.Collections.IEnumerator System.Collections.IEnumerable.GetEnumerator() { throw null; }
         public bool TryGetPropertyValue(string propertyName, out System.Text.Json.Nodes.JsonNode? jsonNode) { throw null; }
+        public bool TryGetPropertyValue(string propertyName, out System.Text.Json.Nodes.JsonNode? jsonNode, out int index) { throw null; }
         public override void WriteTo(System.Text.Json.Utf8JsonWriter writer, System.Text.Json.JsonSerializerOptions? options = null) { }
     }
     public abstract partial class JsonValue : System.Text.Json.Nodes.JsonNode

src/libraries/System.Text.Json/src/System/Text/Json/Nodes/JsonObject.IDictionary.cs

@@ -34,6 +34,47 @@ public void Add(string propertyName, JsonNode? value)
             value?.AssignParent(this);
         }
 
+        /// <summary>
+        ///   Adds an element with the provided name and value to the <see cref="JsonObject"/>, if a property named <paramref name="propertyName"/> doesn't already exist.
+        /// </summary>
+        /// <param name="propertyName">The property name of the element to add.</param>
+        /// <param name="value">The value of the element to add.</param>
+        /// <exception cref="ArgumentNullException"><paramref name="propertyName"/> is null.</exception>
+        /// <returns>
+        ///   <see langword="true"/> if the property didn't exist and the element was added; otherwise, <see langword="false"/>.
+        /// </returns>
+        public bool TryAdd(string propertyName, JsonNode? value) => TryAdd(propertyName, value, out _);
+
+        /// <summary>
+        ///   Adds an element with the provided name and value to the <see cref="JsonObject"/>, if a property named <paramref name="propertyName"/> doesn't already exist.
+        /// </summary>
+        /// <param name="propertyName">The property name of the element to add.</param>
+        /// <param name="value">The value of the element to add.</param>
+        /// <param name="index">The index of the added or existing <paramref name="propertyName"/>. This is always a valid index into the <see cref="JsonObject"/>.</param>
+        /// <exception cref="ArgumentNullException"><paramref name="propertyName"/> is null.</exception>
+        /// <returns>
+        ///   <see langword="true"/> if the property didn't exist and the element was added; otherwise, <see langword="false"/>.
+        /// </returns>
+        public bool TryAdd(string propertyName, JsonNode? value, out int index)
+        {
+            if (propertyName is null)
+            {
+                ThrowHelper.ThrowArgumentNullException(nameof(propertyName));
+            }
+
+#if NET10_0_OR_GREATER
+            var success = Dictionary.TryAdd(propertyName, value, out index);
+#else
+            var success = Dictionary.TryAdd(propertyName, value);
+            index = Dictionary.IndexOf(propertyName);
+#endif
+            if (success)
+            {
+                value?.AssignParent(this);
+            }
+            return success;
+        }
+
         /// <summary>
         ///   Adds the specified property to the <see cref="JsonObject"/>.
         /// </summary>

src/libraries/System.Text.Json/src/System/Text/Json/Nodes/JsonObject.cs

@@ -115,17 +115,42 @@ internal string GetPropertyName(JsonNode? node)
         /// </summary>
         /// <param name="propertyName">The name of the property to return.</param>
         /// <param name="jsonNode">The JSON value of the property with the specified name.</param>
+        /// <exception cref="ArgumentNullException">
+        ///   <paramref name="propertyName"/> is <see langword="null"/>.
+        /// </exception>
         /// <returns>
         ///   <see langword="true"/> if a property with the specified name was found; otherwise, <see langword="false"/>.
         /// </returns>
-        public bool TryGetPropertyValue(string propertyName, out JsonNode? jsonNode)
+        public bool TryGetPropertyValue(string propertyName, out JsonNode? jsonNode) => TryGetPropertyValue(propertyName, out jsonNode, out _);
+
+        /// <summary>
+        ///   Gets the value associated with the specified property name.
+        /// </summary>
+        /// <param name="propertyName">The property name of the value to get.</param>
+        /// <param name="jsonNode">
+        ///   When this method returns, it contains the value associated with the specified property name, if the property name is found;
+        ///   otherwise <see langword="null"/>.
+        /// </param>
+        /// <param name="index">The index of <paramref name="propertyName"/> if found; otherwise, -1.</param>
+        /// <exception cref="ArgumentNullException">
+        ///   <paramref name="propertyName"/> is <see langword="null"/>.
+        /// </exception>
+        /// <returns>
+        ///   <see langword="true"/> if the <see cref="JsonObject"/> contains an element with the specified property name; otherwise, <see langword="false"/>.
+        /// </returns>
+        public bool TryGetPropertyValue(string propertyName, out JsonNode? jsonNode, out int index)
         {
             if (propertyName is null)
             {
                 ThrowHelper.ThrowArgumentNullException(nameof(propertyName));
             }
 
+#if NET10_0_OR_GREATER
+            return Dictionary.TryGetValue(propertyName, out jsonNode, out index);
+#else
+            index = Dictionary.IndexOf(propertyName);
             return Dictionary.TryGetValue(propertyName, out jsonNode);
+#endif
         }
 
         /// <inheritdoc/>

src/libraries/System.Text.Json/tests/System.Text.Json.Tests/JsonNode/JsonObjectTests.cs

@@ -1604,6 +1604,69 @@ public static void JsonObject_IsIList()
             Assert.Equal(-1, jObject.IndexOf("Two"));
         }
 
+        [Fact]
+        public static void TryAdd_NewKey_EmptyJsonObject()
+        {
+            JsonObject jObject = new();
+
+            Assert.True(jObject.TryAdd("First", "value", out var index));
+            Assert.Equal(0, index);
+        }
+
+        [Fact]
+        public static void TryAdd_NewKey()
+        {
+            JsonObject jObject = new()
+            {
+                ["One"] = 1,
+                ["Two"] = "str",
+                ["Three"] = null,
+            };
+
+            Assert.True(jObject.TryAdd("Four", 33, out var index));
+            Assert.Equal(3, index);
+        }
+
+        [Fact]
+        public static void TryAdd_ExistingKey()
+        {
+            JsonObject jObject = new()
+            {
+                ["One"] = 1,
+                ["Two"] = "str",
+                ["Three"] = null,
+            };
+
+            Assert.False(jObject.TryAdd("Two", 33, out var index));
+            Assert.Equal(1, index);
+        }
+
+        [Fact]
+        public static void TryAdd_ThrowsArgumentNullException()
+        {
+            JsonObject jObject = new()
+            {
+                ["One"] = 1,
+                ["Two"] = "str",
+                ["Three"] = null,
+            };
+
+            Assert.Throws<ArgumentNullException>(() => { jObject.TryAdd(null, 33); });
+        }
+
+        [Fact]
+        public static void TryGetPropertyValue_ThrowsArgumentNullException()
+        {
+            JsonObject jObject = new()
+            {
+                ["One"] = 1,
+                ["Two"] = "str",
+                ["Three"] = null,
+            };
+
+            Assert.Throws<ArgumentNullException>(() => { jObject.TryGetPropertyValue(null, out var jsonNode, out var index); });
+        }
+
         [Theory]
         [InlineData(10_000)]
         [InlineData(50_000)]

src/libraries/System.Text.Json/tests/System.Text.Json.Tests/JsonNode/ParseTests.cs

@@ -84,6 +84,60 @@ public static void Parse_TryGetPropertyValue()
             Assert.IsType<JsonObject>(node);
         }
 
+        [Fact]
+        public static void Parse_TryGetPropertyValueWithIndex()
+        {
+            JsonObject jObject = JsonNode.Parse(JsonNodeTests.ExpectedDomJson).AsObject();
+
+            JsonNode? node;
+            int index;
+
+            Assert.True(jObject.TryGetPropertyValue("MyString", out node, out index));
+            Assert.Equal("Hello!", node.GetValue<string>());
+            Assert.Equal(0, index);
+
+            Assert.True(jObject.TryGetPropertyValue("MyNull", out node, out index));
+            Assert.Null(node);
+            Assert.Equal(1, index);
+
+            Assert.True(jObject.TryGetPropertyValue("MyBoolean", out node, out index));
+            Assert.False(node.GetValue<bool>());
+            Assert.Equal(2, index);
+
+            Assert.True(jObject.TryGetPropertyValue("MyArray", out node, out index));
+            Assert.IsType<JsonArray>(node);
+            Assert.Equal(3, index);
+
+            Assert.True(jObject.TryGetPropertyValue("MyInt", out node, out index));
+            Assert.Equal(43, node.GetValue<int>());
+            Assert.Equal(4, index);
+
+            Assert.True(jObject.TryGetPropertyValue("MyDateTime", out node, out index));
+            Assert.Equal("2020-07-08T00:00:00", node.GetValue<string>());
+            Assert.Equal(5, index);
+
+            Assert.True(jObject.TryGetPropertyValue("MyGuid", out node, out index));
+            Assert.Equal("ed957609-cdfe-412f-88c1-02daca1b4f51", node.AsValue().GetValue<Guid>().ToString());
+            Assert.Equal(6, index);
+
+            Assert.True(jObject.TryGetPropertyValue("MyObject", out node, out index));
+            Assert.IsType<JsonObject>(node);
+            Assert.Equal(7, index);
+        }
+
+        [Fact]
+        public static void Parse_TryGetPropertyValueFail()
+        {
+            JsonObject jObject = JsonNode.Parse(JsonNodeTests.ExpectedDomJson).AsObject();
+
+            JsonNode? node;
+            int index;
+
+            Assert.False(jObject.TryGetPropertyValue("NonExistentKey", out node, out index));
+            Assert.Null(node);
+            Assert.Equal(-1, index);
+        }
+
         [Fact]
         public static void Parse_TryGetValue()
         {