Add extension method for JsonSerializerOptions.GetTypeInfo

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

@@ -457,11 +457,13 @@ public JsonSerializerOptions(System.Text.Json.JsonSerializerOptions options) { }
         [System.Diagnostics.CodeAnalysis.RequiresUnreferencedCodeAttribute("Getting a converter for a type may require reflection which depends on unreferenced code.")]
         public System.Text.Json.Serialization.JsonConverter GetConverter(System.Type typeToConvert) { throw null; }
         public System.Text.Json.Serialization.Metadata.JsonTypeInfo GetTypeInfo(System.Type type) { throw null; }
+        public System.Text.Json.Serialization.Metadata.JsonTypeInfo<T> GetTypeInfo<T>() { throw null; }
         public void MakeReadOnly() { }
         [System.Diagnostics.CodeAnalysis.RequiresDynamicCodeAttribute("Populating unconfigured TypeInfoResolver properties with the reflection resolver requires runtime code generation.")]
         [System.Diagnostics.CodeAnalysis.RequiresUnreferencedCodeAttribute("Populating unconfigured TypeInfoResolver properties with the reflection resolver requires unreferenced code.")]
         public void MakeReadOnly(bool populateMissingResolver) { }
         public bool TryGetTypeInfo(System.Type type, [System.Diagnostics.CodeAnalysis.NotNullWhenAttribute(true)] out System.Text.Json.Serialization.Metadata.JsonTypeInfo? typeInfo) { throw null; }
+        public bool TryGetTypeInfo<T>([System.Diagnostics.CodeAnalysis.NotNullWhenAttribute(true)] out System.Text.Json.Serialization.Metadata.JsonTypeInfo<T>? typeInfo) { throw null; }
     }
     public enum JsonTokenType : byte
     {

src/libraries/System.Text.Json/src/System/Text/Json/Serialization/JsonSerializerOptions.Caching.cs

@@ -64,6 +64,15 @@ public JsonTypeInfo GetTypeInfo(Type type)
             return GetTypeInfoInternal(type, resolveIfMutable: true);
         }
 
+        /// <summary>
+        /// Gets the <see cref="JsonTypeInfo"/> contract metadata resolved by the current <see cref="JsonSerializerOptions"/> instance.
+        /// </summary>
+        /// <returns>The contract metadata resolved for <typeparamref name="T"/>.</returns>
+        /// <remarks>
+        /// If the <see cref="JsonSerializerOptions"/> instance is locked for modification, the method will return a cached instance for the metadata.
+        /// </remarks>
+        public JsonTypeInfo<T> GetTypeInfo<T>() => (JsonTypeInfo<T>)GetTypeInfo(typeof(T));
+
         /// <summary>
         /// Tries to get the <see cref="JsonTypeInfo"/> contract metadata resolved by the current <see cref="JsonSerializerOptions"/> instance.
         /// </summary>
@@ -90,6 +99,26 @@ public bool TryGetTypeInfo(Type type, [NotNullWhen(true)] out JsonTypeInfo? type
             return typeInfo is not null;
         }
 
+        /// <summary>
+        /// Tries to get the <see cref="JsonTypeInfo"/> contract metadata resolved by the current <see cref="JsonSerializerOptions"/> instance.
+        /// </summary>
+        /// <param name="typeInfo">The resolved contract metadata, or <see langword="null" /> if no contract could be resolved.</param>
+        /// <returns><see langword="true"/> if a contract for <typeparamref name="T"/> was found, or <see langword="false"/> otherwise.</returns>
+        /// <exception cref="ArgumentException"><typeparamref name="T"/> is not valid for serialization.</exception>
+        /// <remarks>
+        /// If the <see cref="JsonSerializerOptions"/> instance is locked for modification, the method will return a cached instance for the metadata.
+        /// </remarks>
+        public bool TryGetTypeInfo<T>([NotNullWhen(true)] out JsonTypeInfo<T>? typeInfo)
+        {
+            if (TryGetTypeInfo(typeof(T), out var typeInfoOpt))
+            {
+                typeInfo = (JsonTypeInfo<T>)typeInfoOpt;
+                return true;
+            }
+            typeInfo = null;
+            return false;
+        }
+
         /// <summary>
         /// Same as GetTypeInfo but without validation and additional knobs.
         /// </summary>