How can I use the Get All Actors Of Class Matching Tag Query node?

Development Programming & Scripting Blueprint
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7

quick fix

To use GetAllActorsOfClassMatchingTagQuery, your classes have to implements the GameplayTagAssetInterface (see IGameplayTagAssetInterface | Unreal Engine 5.5 Documentation | Epic Developer Community)

To do so, you have to create a new C++ class like this

.Build.cs

[...]

PrivateDependencyModuleNames.AddRange(
	new string[]
    {

[...]

        "GameplayTags",

    });

[...]

.h

#include "CoreMinimal.h"
#include "Engine/GameInstance.h" 
#include "GameFramework/Actor.h"
#include "GameplayTagAssetInterface.h"

#include "MyActor.generated.h"

UCLASS()
class MY_API AMyActor : public AActor, public IGameplayTagAssetInterface
{

	GENERATED_BODY()

public:

	UPROPERTY(BlueprintReadOnly, EditAnywhere, Category = "Gameplay", meta = (ToolTip = "Container for gameplay tags"))
	FGameplayTagContainer GameplayTags;

	UFUNCTION(BlueprintCallable, Category = "Gameplay")
	virtual void GetOwnedGameplayTags(FGameplayTagContainer& TagContainer) const;

.cpp


void AMyActor::GetOwnedGameplayTags(FGameplayTagContainer& TagContainer) const
{
	TagContainer = GameplayTags;
}

reason

A peep in the source code of UBlueprintGameplayTagLibrary make it clear how the GetAllActorsOfClassMatchingTagQuery is working.

in Unreal 5.4.4, BlueprintGameplayTagLibrary.cpp line 120, after getting all the actors of the specified class, the code validate the presence of the inteface.

				IGameplayTagAssetInterface* GameplayTagAssetInterface = Cast<IGameplayTagAssetInterface>(Actor);
				if (GameplayTagAssetInterface != nullptr)
				{

i hope it still helps :wink: