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Casting from c++ to blueprint

When I try to cast my c++ actor class to it's blueprint class, it fails. I'm not sure why since the blueprint class was created from the c++ class.

The createItem function spawns a new Aitem and returns its pointer. In blueprints, I then attempt to cast it but it always fails : imagelike this.

 Aitem* ADungeonLevel::createItem(FName iname)
 Aitem *newitem = NULL;
 FVector location(500.f, 500.f, 500.f);
 FRotator rotation(0.f, 0.f, 0.f);
 FActorSpawnParameters spawninfo;
 spawninfo.SpawnCollisionHandlingOverride = ESpawnActorCollisionHandlingMethod::AlwaysSpawn;

 for (int i = 0; i < ItemsPtr->AllItems.Max(); i++)
     for (int n = 0; n < ItemsPtr->AllItems[i].Items.Max(); n++)
         if (ItemsPtr->AllItems[i].Items[n].EditorName == iname)
             newitem = GetWorld()->SpawnActor<Aitem>(location, rotation, spawninfo);
             // set item data


     if (newitem) break;
 if(!newitem) UE_LOG(LogItem, Error, TEXT("Error creating new item") );

 return newitem;
Product Version: UE 4.18
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asked Feb 04 '18 at 06:11 AM in C++ Programming

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avatar image erik321123 Feb 04 '18 at 12:53 PM

So you try to cast a AItem to AItem or what? Your question isn't really clear, perhaps you can add a BP screenshot

avatar image postal83 Feb 04 '18 at 03:20 PM

Thanks I tried to clarify it a bit. I have a blueprint class that is created from my actor c++ class. When I try to cast my c++ class to the blueprint class it fails?

avatar image erik321123 Feb 04 '18 at 03:25 PM

is your spawn, and function successful? Is it really the cast that fails or the getting of data to cast?

avatar image erik321123 Feb 04 '18 at 03:26 PM

Also is AItem inherited from BP_Itembase?

avatar image postal83 Feb 04 '18 at 03:32 PM

BP_Itembase was created by "create blueprint class based on item" in the content browser by right clicking on the CPP class.

The spawn is successful and I can manipulate the Aitem object before I try to cast it and can even get it to render its sprite, but for whatever reason it won't cast to a blueprint class that was derived from the c++ class.

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I think I know what is going wrong, you are trying to 'down'cast. A super class is casted to a child class. That isn't possible, you can only cast 'up', to a super class.

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answered Feb 04 '18 at 03:41 PM

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avatar image postal83 Feb 04 '18 at 03:48 PM

Ah that's a bummer but makes sense now. Thanks for the answer. Back to the drawing board...

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