Polymorphism

Sometimes your models will need lists of objects with a shared heritage

apiVersion: kadense.io/v1
kind: MalleableModule
metadata:
  name: test-polymorph
  namespace: default
spec:
  classes:
    PolymorphicBaseClass:
      discriminatorProperty: "type"
      properties:
        BaseStringProperty:
          type: string
    
    PolymorphicDerivedClass1:
      baseClass: PolymorphicBaseClass
      typeDiscriminator: DerivedString
      properties:
        DerivedStringProperty:
          type: string
    
    PolymorphicDerivedClass2:
      baseClass: PolymorphicBaseClass
      typeDiscriminator: DerivedInt
      properties:
        DerivedIntProperty:
          type: int    

The MalleableAssemblyBuilder will populate the MalleableAssembly that it generates with the configuration for the JsonSerializer. This can then be passed into the MalleablePolymorphicTypeResolver and in turn into the JsonSerializerOptions as follows:

public IList<MalleableAssembly> Assemblies { get; }
protected MalleablePolymorphicTypeResolver? TypeResolver { get; set; }

public JsonSerializerOptions GetJsonSerializerOptions()
{
    if(TypeResolver == null)
    {
        TypeResolver = new MalleablePolymorphicTypeResolver();
        foreach (var assembly in Assemblies)
        {
            TypeResolver.MalleableAssembly.Add(assembly);
        }
    }
    var options = new JsonSerializerOptions
    {
        TypeInfoResolver = TypeResolver,
        WriteIndented = true
    };

    return options;
}

This can then be called when serializing or deserializing the objects:

// serialize to stream
await System.Text.Json.JsonSerializer.SerializeAsync<T>(stream, content, this.GetJsonSerializerOptions());

// deserialize from stream
var message = await JsonSerializer.DeserializeAsync<TMessage>(stream, this.GetJsonSerializerOptions());

// serialize to a HttpResponse stream
await context.Response.WriteAsJsonAsync<T>(content, this.GetJsonSerializerOptions());

// create content for a HttpRequest
var content = JsonContent.Create(instance, instance.GetType(), options: GetJsonSerializerOptions())

Of course, when using the Malleable Workflow Engine all of the serializers should implement this by default.