Blueprint recompile invalidates references in native component

Development Programming & Scripting C++
5

I’m probably a bit confused as to the basics here. Let’s say I have these types:


UCLASS()
class UTestMember : public UObject
{
    GENERATED_BODY()
public:
    UPROPERTY(EditAnywhere)
    int32 Value = 0;
};

UCLASS()
class UTestContainer : public UObject
{
    GENERATED_BODY()
public:
    UTestContainer()
    {
        MemberA = CreateDefaultSubobject<UTestMember>(FName(TEXT("MA")));
        MemberB = CreateDefaultSubobject<UTestMember>(FName(TEXT("MB")));
    }

    UPROPERTY(Transient, VisibleAnywhere)
    UTestMember* MemberA;

    UPROPERTY(Transient, VisibleAnywhere)
    UTestMember* MemberB;
};

In some component, I create an instance of UTestContainer (at edit-time):


    TestContainer = NewObject<UTestContainer>(this, UTestContainer::StaticClass(), FName(TEXT("TisAFineDay")));

where TestContainer is declared as:


    UPROPERTY(EditAnywhere, Category="Test")
    UTestContainer* TestContainer = nullptr;

I edit the values in MemberA and MemberB in a few different components and note that they each hold unique values for UTestMember::Value. On save, however, they are not persisted since transient has been specified. On load they take their value from the CDO, which I guess is expected. This is the instance data I’m talking about. If I remove the transient specifier, data is persisted and all seems well. In this case I might have been lucky as there was no recycling happening in NewObject, bit hard to tell. But I suppose I could guarantee proper behavior by adding the DefaultToInstanced class specifier to UTestMember? (Just like UActorComponent.)

There is likely something wrong with my reasoning, but what? :slight_smile: