UBlackBoardComponent is undefined even when BehaviorTree/BlackboardComponent.h is included

Development Programming & Scripting
1

I have followed many tutorials and have done EnemyAIController like this:

EnemyAIController.h:

#pragma once
#include "CoreMinimal.h"
#include "AIController.h"
#include "EnemyAIController.generated.h"

UCLASS()
class OLIVIA_API AEnemyAIController : public AAIController
{
	GENERATED_BODY()
public:
	AEnemyAIController();
	virtual void OnPossess(APawn* InPawn)override;
protected:
	UPROPERTY(Transient)
		class UBlackBoardComponent *BlackBoardComp;
	UPROPERTY(Transient)
		class UBehaviorTreeComponent *BehaviorTreeComp;
	uint8 EnemyKeyID;
};

EnemyAIController.cpp:

#include "EnemyAIController.h"
#include "BehaviorTree/BlackboardComponent.h"
#include "BehaviorTree/Blackboard/BlackboardKeyAllTypes.h"
#include "BehaviorTree/BehaviorTree.h"
#include "BehaviorTree/BehaviorTreeComponent.h"
#include "EnemyCharacter.h"

AEnemyAIController::AEnemyAIController()
{
	BlackBoardComp = CreateDefaultSubobject<UBlackBoardComponent>(TEXT("BlackBoardComp"));
	BehaviorTreeComp = CreateDefaultSubobject<UBehaviorTreeComponent>(TEXT("BehaviorTreeComp"));
}

void AEnemyAIController::OnPossess(APawn * InPawn)
{
	Super::OnPossess(InPawn);
	
	AEnemyCharacter *c = Cast<AEnemyCharacter>(InPawn);
	if (c && c->botBehavior)
	{
		BlackBoardComp->InitializeBlackBoard(*c->botBehavior->BlackboardAsset);
		EnemyKeyID = BlackBoardComp->GetKeyID("TargetActor");
		BehaviorTreeComp->StartTree(*c->botBehavior);
	}
}

Even with the included headers, the .cpp can’t recognize UBlackBoardComponent and when compiling it complains that error C2027: use of undefined type ‘UBlackBoardComponent’.

I have tried other ways like moving those includes to the EnemyAIController.h, but the error persists.

Please note that UBehaviorTreeComponent is good, only UBlackBoardComponent is undefined.

Also I did add “AIModule” to the .Build.cs, then rebuild the solution, but still the error persists.

I clicked and opened BehaviorTree/BlackboardComponent.h and it looks fine.

...
class UBrainComponent;
...
UCLASS(ClassGroup = AI, meta = (BlueprintSpawnableComponent))
class AIMODULE_API UBlackboardComponent : public UActorComponent
{
...

Am I missing some other includes than BehaviorTree/BlackboardComponent.h?
Any ideas? Thanks.

2

Take a look at this open source tutorial header/cpp for their AI.

Header

cpp

check these out to see what you should include.

And it seems like you wrote BlackBoardComponent when it should be BlackboardComponent.

3

It’s just a typo, it should be UBlackboardComponent rather than UBlackBoardComponent.