Fixed JSON serialization issue between Annotated base class and deriv… #12
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…ed classes due to 'Type' name conflict.
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…ed classes due to 'Type' name conflict.
Experienced the following error during MCP server testing locally:
MCP error -32602: The type 'ModelContextProtocol.NET.Core.Models.Protocol.Shared.Content.TextContent' contains property 'type' that conflicts with an existing metadata property name.
Root Cause Determination:
In Annotated.cs, the base class has:
csharpCopy[JsonPolymorphic(TypeDiscriminatorPropertyName = "type")]
[JsonDerivedType(typeof(TextContent), "text")]
[JsonDerivedType(typeof(ImageContent), "image")]
[JsonDerivedType(typeof(EmbeddedResource), "resource")]
The base Annotated class uses [JsonPolymorphic] with TypeDiscriminatorPropertyName = "type" to handle polymorphic serialization. Each derived content class (TextContent, ImageContent, EmbeddedResource) defined a Type property that returned a string constant. During serialization, the system tried to use both the discriminator property "type" (from the JsonPolymorphic attribute) and the actual property "Type" from the class, causing a naming conflict
Changes Made:
Added [JsonIgnore] attribute to the Type property in:
TextContent.cs
ImageContent.cs
EmbeddedResource.cs
No unit tests found in the solution, but I tested the library with these changes locally and the error has been fixed.