Add CreateJson overloads to BinaryContent for simplified JSON serialization

sdk/core/System.ClientModel/api/System.ClientModel.net8.0.cs

@@ -22,9 +22,12 @@ protected AuthenticationTokenProvider() { }
     public abstract partial class BinaryContent : System.IDisposable
     {
         protected BinaryContent() { }
+        public virtual string? MediaType { get { throw null; } }
         public static System.ClientModel.BinaryContent Create(System.BinaryData value) { throw null; }
         public static System.ClientModel.BinaryContent Create(System.IO.Stream stream) { throw null; }
         public static System.ClientModel.BinaryContent Create<T>(T model, System.ClientModel.Primitives.ModelReaderWriterOptions? options = null) where T : System.ClientModel.Primitives.IPersistableModel<T> { throw null; }
+        public static System.ClientModel.BinaryContent CreateJson<T>(T jsonSerializable, System.Text.Json.JsonSerializerOptions? options = null) { throw null; }
+        public static System.ClientModel.BinaryContent CreateJson<T>(T jsonSerializable, System.Text.Json.Serialization.Metadata.JsonTypeInfo<T> jsonTypeInfo) { throw null; }
         public abstract void Dispose();
         public abstract bool TryComputeLength(out long length);
         public abstract void WriteTo(System.IO.Stream stream, System.Threading.CancellationToken cancellationToken = default(System.Threading.CancellationToken));

sdk/core/System.ClientModel/api/System.ClientModel.netstandard2.0.cs

@@ -22,9 +22,12 @@ protected AuthenticationTokenProvider() { }
     public abstract partial class BinaryContent : System.IDisposable
     {
         protected BinaryContent() { }
+        public virtual string? MediaType { get { throw null; } }
         public static System.ClientModel.BinaryContent Create(System.BinaryData value) { throw null; }
         public static System.ClientModel.BinaryContent Create(System.IO.Stream stream) { throw null; }
         public static System.ClientModel.BinaryContent Create<T>(T model, System.ClientModel.Primitives.ModelReaderWriterOptions? options = null) where T : System.ClientModel.Primitives.IPersistableModel<T> { throw null; }
+        public static System.ClientModel.BinaryContent CreateJson<T>(T jsonSerializable, System.Text.Json.JsonSerializerOptions? options = null) { throw null; }
+        public static System.ClientModel.BinaryContent CreateJson<T>(T jsonSerializable, System.Text.Json.Serialization.Metadata.JsonTypeInfo<T> jsonTypeInfo) { throw null; }
         public abstract void Dispose();
         public abstract bool TryComputeLength(out long length);
         public abstract void WriteTo(System.IO.Stream stream, System.Threading.CancellationToken cancellationToken = default(System.Threading.CancellationToken));

sdk/core/System.ClientModel/src/Message/BinaryContent.cs

@@ -5,6 +5,8 @@
 using System.ClientModel.Internal;
 using System.ClientModel.Primitives;
 using System.IO;
+using System.Text.Json;
+using System.Text.Json.Serialization.Metadata;
 using System.Threading;
 using System.Threading.Tasks;
 
@@ -18,6 +20,11 @@ public abstract class BinaryContent : IDisposable
 {
     private static readonly ModelReaderWriterOptions ModelWriteWireOptions = new ModelReaderWriterOptions("W");
 
+    /// <summary>
+    /// Gets the media type of the content.
+    /// </summary>
+    public virtual string? MediaType { get; }
+
     /// <summary>
     /// Creates an instance of <see cref="BinaryContent"/> that contains the
     /// bytes held in the provided <see cref="BinaryData"/> instance.
@@ -65,6 +72,39 @@ public static BinaryContent Create(Stream stream)
         return new StreamBinaryContent(stream);
     }
 
+    /// <summary>
+    /// Creates an instance of <see cref="BinaryContent"/> that contains the
+    /// JSON representation of the provided object.
+    /// </summary>
+    /// <typeparam name="T">The type of the object to serialize.</typeparam>
+    /// <param name="jsonSerializable">The object to serialize to JSON.</param>
+    /// <param name="options">The <see cref="JsonSerializerOptions"/> to use for serialization.
+    /// If not provided, the default options will be used.</param>
+    /// <returns>An instance of <see cref="BinaryContent"/> that contains the
+    /// JSON representation of the provided object.</returns>
+#pragma warning disable AZC0014 // Avoid using banned types in public API
+    public static BinaryContent CreateJson<T>(T jsonSerializable, JsonSerializerOptions? options = default)
+#pragma warning restore AZC0014 // Avoid using banned types in public API
+    {
+        return Create(BinaryData.FromObjectAsJson(jsonSerializable, options));
+    }
+
+    /// <summary>
+    /// Creates an instance of <see cref="BinaryContent"/> that contains the
+    /// JSON representation of the provided object using the specified JSON type information.
+    /// </summary>
+    /// <typeparam name="T">The type of the object to serialize.</typeparam>
+    /// <param name="jsonSerializable">The object to serialize to JSON.</param>
+    /// <param name="jsonTypeInfo">The <see cref="JsonTypeInfo{T}"/> to use for serialization.</param>
+    /// <returns>An instance of <see cref="BinaryContent"/> that contains the
+    /// JSON representation of the provided object.</returns>
+#pragma warning disable AZC0014 // Avoid using banned types in public API
+    public static BinaryContent CreateJson<T>(T jsonSerializable, JsonTypeInfo<T> jsonTypeInfo)
+#pragma warning restore AZC0014 // Avoid using banned types in public API
+    {
+        return Create(BinaryData.FromObjectAsJson(jsonSerializable, jsonTypeInfo));
+    }
+
     /// <summary>
     /// Attempts to compute the length of the underlying body content, if available.
     /// </summary>

sdk/core/System.ClientModel/tests/Message/BinaryContentTests.cs

@@ -4,6 +4,7 @@
 using System.ClientModel.Primitives;
 using System.IO;
 using System.Text.Json;
+using System.Text.Json.Serialization.Metadata;
 using System.Threading;
 using System.Threading.Tasks;
 using Azure.Core.TestFramework;
@@ -156,4 +157,59 @@ public void StreamBinaryContentMustBeSeekable()
 
         Assert.Throws<ArgumentException>(() => { BinaryContent.Create(stream); });
     }
+
+    [Test]
+    public async Task CanCreateAndWriteJsonBinaryContentFromObject()
+    {
+        var testObject = new { Name = "test", Value = 42 };
+        using BinaryContent content = BinaryContent.CreateJson(testObject);
+
+        Assert.IsTrue(content.TryComputeLength(out long length));
+        Assert.Greater(length, 0);
+
+        MemoryStream stream = new MemoryStream();
+        await content.WriteToSyncOrAsync(stream, CancellationToken.None, IsAsync);
+
+        string json = System.Text.Encoding.UTF8.GetString(stream.ToArray());
+        Assert.IsTrue(json.Contains("test"));
+        Assert.IsTrue(json.Contains("42"));
+    }
+
+    [Test]
+    public async Task CanCreateAndWriteJsonBinaryContentWithOptions()
+    {
+        var testObject = new { Name = "TEST", Value = 42 };
+        var options = new JsonSerializerOptions { PropertyNamingPolicy = JsonNamingPolicy.CamelCase };
+
+        using BinaryContent content = BinaryContent.CreateJson(testObject, options);
+
+        Assert.IsTrue(content.TryComputeLength(out long length));
+        Assert.Greater(length, 0);
+
+        MemoryStream stream = new MemoryStream();
+        await content.WriteToSyncOrAsync(stream, CancellationToken.None, IsAsync);
+
+        string json = System.Text.Encoding.UTF8.GetString(stream.ToArray());
+        // With camelCase naming policy, "Name" should become "name"
+        Assert.IsTrue(json.Contains("name"));
+        Assert.IsTrue(json.Contains("value"));
+    }
+
+    [Test]
+    public void JsonBinaryContentMatchesBinaryDataFromObjectAsJson()
+    {
+        var testObject = new { Name = "test", Value = 42 };
+
+        // Create using the new CreateJson method
+        using BinaryContent content = BinaryContent.CreateJson(testObject);
+
+        // Create using the existing pattern
+        BinaryData binaryData = BinaryData.FromObjectAsJson(testObject);
+        using BinaryContent expectedContent = BinaryContent.Create(binaryData);
+
+        // They should have the same length
+        Assert.IsTrue(content.TryComputeLength(out long contentLength));
+        Assert.IsTrue(expectedContent.TryComputeLength(out long expectedLength));
+        Assert.AreEqual(expectedLength, contentLength);
+    }
 }