InstancedStruct

This example only works with UE5.0+

Starting with UE 5.0 there's a new plugin StructUtils featuring a struct type called FInstancedStruct. It's shares the same idea to previous AnyStruct example, while it has proper asset serialization logic and editor support.

Given a struct hierarchy like this:

// DataConfigExtra/Public/DataConfig/Extra/Types/DcExtraTestFixtures.h
USTRUCT(BlueprintType)
struct FDcStructShapeBase
{
    GENERATED_BODY()
    
    UPROPERTY(EditAnywhere) FName ShapeName;
};

USTRUCT(BlueprintType)
struct FDcStructShapeRectangle : public FDcStructShapeBase
{
    GENERATED_BODY()
    
    UPROPERTY(EditAnywhere) float Height;
    UPROPERTY(EditAnywhere) float Width;
};

USTRUCT(BlueprintType)
struct FDcStructShapeCircle : public FDcStructShapeBase
{
    GENERATED_BODY()
    
    UPROPERTY(EditAnywhere) float Radius;
};

You can use FInstancedStruct specified with a BaseStruct meta to reference to a polymorphism instance:

// DataConfigEngineExtra5/Public/DataConfig/EngineExtra/SerDe/DcSerDeInstancedStruct.h
UPROPERTY(EditAnywhere, meta = (BaseStruct = "/Script/DataConfigExtra.DcStructShapeBase"))
FInstancedStruct InstancedStruct1;

UPROPERTY(EditAnywhere, meta = (BaseStruct = "DcStructShapeBase"))
FInstancedStruct InstancedStruct2;

The best part is that the editor is also working as intended:

Prior to this you'll need to setup Sub Objects for similar behavior, which costs unnecessary overhead.

FInstancedStruct can also be serialized to and from JSON with DataConfig:

• DcSerDeInstancedStruct.h
• DcSerDeInstancedStruct.cpp

// DataConfigExtra5/Public/DataConfig/EngineExtra/SerDe/DcSerDeInstancedStruct.h
USTRUCT()
struct FDcEngineExtra5InstancedStruct1
{
    GENERATED_BODY()

    UPROPERTY() FInstancedStruct InstancedStruct1;
    UPROPERTY() FInstancedStruct InstancedStruct2;
    UPROPERTY() FInstancedStruct InstancedStruct3;
};

// DataConfigExtra5/Private/DataConfig/EngineExtra/SerDe/DcSerDeInstancedStruct.cpp
FString Str = TEXT(R"(
    {
        "InstancedStruct1" : {
            "$type" : "DcExtraTestSimpleStruct1",
            "NameField" : "Foo"
        },
        "InstancedStruct2" : {
            "$type" : "DcExtraTestStructWithColor1",
            "ColorField1" : "#0000FFFF",
            "ColorField2" : "#FF0000FF"
        },
        "InstancedStruct3" : null
    }
)");

Note how the custom FColor <-> "#RRGGBBAA" conversion recursively works within FInstancedStruct.