Assigning TSubClassOf in C++

Development Programming & Scripting
1

Hi,

I’m doing some modifications on the First Person Example project and I want to assign/change the type of projectile that is used in code.

The variable is of type TSubclassOf. I’m using the code found here to get a reference to the blueprint of the projectile I want to use.

So in my function I have something like this:

void ACPP_FPS_LearnCharacter::SetProjectile(FName AssetPath) { ProjectileClass = *LoadObjFromPath<ACPP_FPS_LearnProjectile>(AssetPath); }

However the error I get is that ProjectileClass is of type TSubclassOf and the return value is of type ACPP_FPS_LearnProjectile so the assignment fails. I can just use a regular pointer but I was wondering how to do that with TSubclassOf.

2

I’m not sure about this, but I think your issue may be that your code is attempting to load an object of type ACPP_FPS_LearnProjectile, whereas what you want to do is load the blueprint/class itself. Try the following (note the omission of the * you had):

ProjectileClass = LoadObjFromPath<UClass>(AssetPath);

You may perhaps need to edit your asset path by appending ‘_C’ to the end of it, I’m not sure.

You could perhaps try UBlueprint instead of UClass too, however I think I read somewhere that this use was being phased out.

3

Hi Swiftle,

Try to use:

UPROPERTY(EditAnywhere, BlueprintReadWrite, Category = Options)
TSubclassOf<class AProjectileBase> ProjectileClass;

In this case, you can setup ProjectileClass in blueprint to all blueprints or classes derived from AProjectileBase.

Hope it helps!

4

Hello,

I know I can do that in Blueprints but I actually want to do it in C++. I want to be able to switch my projectiles. Let’s say I have a bouncing projectile and an explosive projectile. I want to be able to change between them and I really wanted to write the logic in C++. I’ve actually tried to replace TSubclassOf<> with a simple pointer to the the class but the I when I try to spawn it nothing happens. The SpawnActor in my Fire() function wont recognize the UClass* reference.

Again this is all done with the C++ First Person Shooter example in UE4. I haven’t added any new classes. Oh and btw I’ve tried to do it with the use of ConstructorHelpers::FObjectFinder but I can only call that function in the class constructor which is rather limiting.
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5

Have you tried LoadClass() instead of LoadObjFromPath()?

6

Is that the correct syntax:
ProjectileClass = LoadClass < MyProjectile > (NULL, TEXT("Blueprint'/Game/Blueprints/Projectile.Projectile'"), NULL, LOAD_None, NULL); ?

7

I tried what you suggested but the ProjectileClass remains empty after the assignment. Also using UBlueprint instead of UClass results in an error about incorrect assignment.

8

Try to use this

 auto pObj = LoadObjFromPath<ACPP_FPS_LearnProjectile>(AssetPath);
    if (pObj)
       ProjectileClass = pObj->GetClass();
9

Guys thank you all for your help I figured it out. The problem is the string that I was using, as kamrann suggested I have to add a _C. For example, my original blueprint reference was this: Blueprint'/Game/Blueprints/Projectile.Projectile'. However this would always assign NULL to my Projectile Class. However once I changed the string to /Game/Blueprints/Projectile.Projectile_C and used LoadClass, everything worked correctly and the Blueprint was assigned. My guess is that the first string is a reference to a UBlueprint and I actually need the UClass from that UBlueprint.