Initial commit

src/mcpdotnet/Utils/Json/ContentJsonConverter.cs

@@ -0,0 +1,51 @@
+// Utils/Json/ContentJsonConverter.cs
+namespace McpDotNet.Utils.Json;
+
+using System.Text.Json;
+using System.Text.Json.Serialization;
+using global::McpDotNet.Protocol.Types;
+
+/// <summary>
+/// JSON converter for IContent that handles polymorphic deserialization based on the "type" property.
+/// </summary>
+public class ContentJsonConverter : JsonConverter<IContent>
+{
+    public override IContent? Read(ref Utf8JsonReader reader, Type typeToConvert, JsonSerializerOptions options)
+    {
+        if (reader.TokenType != JsonTokenType.StartObject)
+        {
+            throw new JsonException("Expected StartObject token");
+        }
+
+        using var doc = JsonDocument.ParseValue(ref reader);
+        var root = doc.RootElement;
+
+        if (!root.TryGetProperty("type", out var typeProperty))
+        {
+            throw new JsonException("Missing 'type' property");
+        }
+
+        var type = typeProperty.GetString();
+        return type switch
+        {
+            "text" => JsonSerializer.Deserialize<TextContent>(root.GetRawText(), options),
+            "image" => JsonSerializer.Deserialize<ImageContent>(root.GetRawText(), options),
+            _ => throw new JsonException($"Unknown content type: {type}")
+        };
+    }
+
+    public override void Write(Utf8JsonWriter writer, IContent value, JsonSerializerOptions options)
+    {
+        switch (value)
+        {
+            case TextContent text:
+                JsonSerializer.Serialize(writer, text, options);
+                break;
+            case ImageContent image:
+                JsonSerializer.Serialize(writer, image, options);
+                break;
+            default:
+                throw new JsonException($"Unknown content type: {value.GetType()}");
+        }
+    }
+}