PolymorphicJsonTypeInfoResolver 0.1.11

Polymorphic Json Type Info Resolver

Polymorphic Json Type Info Resolver allows you to configure polymorphism on the contract model without polluting the domain model with attributes. This library leverages the polymorphic type serialization feature introduced in .NET7.

Installation

You can install the Polymorphic Json Type Info Resolver via NuGet Package Manager or by using the .NET CLI.

NuGet Package Manager:

1. Search for "PolymorphicJsonTypeInfoResolver" in the NuGet Package Manager in Visual Studio.
2. Click "Install".

.NET CLI:

dotnet add package PolymorphicJsonTypeInfoResolver

Usage

Here's an example of how to use Polymorphic Json Type Info Resolver:

var options = new JsonSerializerOptions {
    TypeInfoResolver = new PolymorphicTypeInfoResolver()
        .Type<Shape>(x => x
            .DerivedTypes
            .Add<Square>("square")
            .Add<Circle>("circle"))
};
        
var json = JsonSerializer.Serialize(new Box(new Circle(10)), options);

In the above code snippet, we create a new instance of JsonSerializerOptions and set its TypeInfoResolver property to an instance of PolymorphicTypeInfoResolver. We then configure the resolver to serialize objects of type Shape with a $type property that specifies the derived type (Square or Circle). Finally, we serialize a Box object containing a Circle object with a radius of 10.

Remark: the Add method can use the type name for discriminator, but I'm not sure that's a good idea after all. Since it is part of your contract you may want to decouple it so it does not automatically change as part of refactoring.

{
    "Shape": {
        "$type":"circle",
        "Radius":10
    }
}

To supply a factory for the polymorphic JSON options, you can use the following code:

var options = new JsonSerializerOptions {
    TypeInfoResolver = new PolymorphicTypeInfoResolver(options: () => new JsonPolymorphismOptions {
        TypeDiscriminatorPropertyName = "$TYPE"
    })
};

In the above code snippet, we create a new instance of JsonSerializerOptions and set its TypeInfoResolver property to an instance of PolymorphicTypeInfoResolver. We then supply a factory function that returns an instance of JsonPolymorphismOptions with a custom $TYPE type discriminator property name.

To opt-in to all derived types from its own assembly or the specified assembly, you can use the following code:

new JsonSerializerOptions {
    TypeInfoResolver = new PolymorphicTypeInfoResolver()
        .Type<Shape>(x => x
            .DerivedTypes
            .AddAllAssignableTo<Shape>(t => t.Name)
            .AddAllAssignableTo<Shape, Parallelogram>(t => t.Name))
};

In the above code snippet, we create a new instance of JsonSerializerOptions and set its TypeInfoResolver property to an instance of PolymorphicTypeInfoResolver. We then configure the resolver to serialize objects of type Shape with all derived types assignable to Shape from its own assembly and the assembly where Parallelogram is located with their name as the type discriminator.

Remark: this readme was peer-reviewed by ChatGPT.

Happy coding!