Unreal Engine 5 can't find TStaticArray

Question

My problem revolves around a data asset class describing a survivor for my game. The class contains an FText for both the name and description and it compiled fine. However, after I added a property for teachable perks, which every survivor has 3 of, it started causing issues. At first, I thought I just forgot to include the necessary header, that being "Containers/StaticArray.h", but even after that I still get an error telling me that "a class, delegate, enum, or struct, with the name TStaticArray can not be found". I know that I have the correct header because I checked the documentation for the TStaticArray type so I'm stuck. It might be worth noting that intellisense does show the correct type, I can even navigate to the definition by holding down control and left-clicking on it in Visual Studio, but the compiler doesn't seem to find it.

Any help is much appreciated.

Here's the full code:

#pragma once

#include "CoreMinimal.h"
#include "Engine/DataAsset.h"
#include "Containers/StaticArray.h"
#include "SurvivorData.generated.h"

UCLASS()
class KILLERGAME_API USurvivorData : public UPrimaryDataAsset
{
    GENERATED_BODY()
    
public:
    UPROPERTY(BlueprintReadOnly, EditDefaultsOnly)
    FText Name;

    UPROPERTY(BlueprintReadOnly, EditDefaultsOnly)
    FText Description;

    UPROPERTY(BlueprintReadOnly, EditDefaultsOnly)
    TStaticArray<TObjectPtr<class UPerkData>, 3> TeachablePerks;
};

UPerkData is just another data asset describing a perk.

Tools used:

• Visual Studio 2022 17.8.3
• Unreal Engine 5.3

Answer 1

So I think I've figured it out.

I had the correct header file and the template type doesn't matter. TStaticArray simply doesn't work as a UPROPERTY. Using it as a normal field works fine.

So that answers that.

No to my workaround to achieve the limiting of the array length to 3. I had to fall back to old faithful and use a simple TArray. I only care about limiting its size in the editor since it is a data asset. So I added a constructor that initializes the array with 3 empty slots, added EditFixedSize to the metadata, and overwrote the const version of the IsDataValid method derived from UObject. In it, I simply define the object as invalid should the array size not equal 3.

Here's the code:

Header:

#pragma once

#include "CoreMinimal.h"
#include "Engine/DataAsset.h"
#include "PerkData.h"
#include "SurvivorData.generated.h"

UCLASS()
class KILLERGAME_API USurvivorData : public UPrimaryDataAsset
{
    GENERATED_BODY()
    
public:
    UPROPERTY(BlueprintReadOnly, EditDefaultsOnly)
    FText Name;

    UPROPERTY(BlueprintReadOnly, EditDefaultsOnly)
    FText Description;

    UPROPERTY(BlueprintReadOnly, EditDefaultsOnly, EditFixedSize)
    TArray<UPerkData*> TeachablePerks;

    USurvivorData();

    virtual EDataValidationResult IsDataValid(FDataValidationContext& Context) const override;
};

CPP:

#include "SurvivorData.h"
#include "Misc/DataValidation.h"

USurvivorData::USurvivorData()
    : TeachablePerks({ nullptr, nullptr, nullptr })
{ }

EDataValidationResult USurvivorData::IsDataValid(FDataValidationContext& Context) const
{
    if (TeachablePerks.Num() != 3)
    {
        Context.AddError(FText::FromString(TEXT("Number of teachable perks can only be 3!")));
        return EDataValidationResult::Invalid;
    }

    return EDataValidationResult::Valid;
}

For anyone curious, I'd encourage them to read the official documentation about data validation here.

So that wraps it up. TStaticArray is great for use as a private field or as a variable in code. Should you need an array for use in the editor however, blueprint or not, you should use TArray.