Need to identify what's wrong

Development Programming & Scripting Blueprint
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1

I have defined a struct that actually exists in the UE (Unreal Engine) editor, its representation is in the form of a file. And now I want to reference it in C++ code using a pointer.

图像_2023-06-30_193634177
图像_2023-06-30_193634177994×367 45.9 KB

To do this, I used the following definition in the header file:

USTRUCT(BlueprintType)
struct FItemStatRow
{
	GENERATED_BODY()
};

UCLASS(Blueprintable, Category = "DataDriven")
class DATAASSET_API UMyDataFunctionLibrary : public UBlueprintFunctionLibrary
{
	GENERATED_BODY()

public:
	UMyDataFunctionLibrary();

	static FItemStatRow* MyStructPtr;
}

I have written the following code in the source file:

FItemStatRow* UMyDataFunctionLibrary::MyStructPtr = nullptr;

UMyDataFunctionLibrary::UMyDataFunctionLibrary() {
	static ConstructorHelpers::FObjectFinder<UClass> StructFinder(TEXT("UserDefinedStruct'/Game/DataTable/PrepareData/S_ItemStatRow.S_ItemStatRow'"));
	if (StructFinder.Succeeded()) {
		UClass* StructClass = StructFinder.Object;
		/*if (StructClass) {
			MyStructPtr = Cast<FItemStatRow>(StructClass->GetDefaultObject());
		}*/
	}
}

The commented-out portion that I have is unable to compile, and I’m not sure what the issue is or how to fix it.
The error message specifically states that “StaticClass” is not a member of “FItemStatRow”.

2

UStructs can’t be UClasses.
Although structs and classes are extremely similar, UStructs and UClasses aren’t.

Though, this wouldn’t work even if it was a class. S_ItemStatRow doesn’t inherit from FItemStatRow, so you would either get a crash or a nullptr. Might as well just use a void*.

What you should do is move all the variables in S_ItemStatRow to FItemStatRow and just get rid of it. Seeing how it has row in the name, I assume this is a data table row. To make the struct data-table compatible, simply make the struct inherit from FTableRowBase and make all variables at least EditDefaultsOnly. Like so:
image

3

for some reason, the struct definition must be done in the Blueprint Editor

4

What do you mean by “some reason”?
Data tables do not need their based structure to be blueprint-defined.
You’ll likely also want the properties to be blueprint readwrite.

If you want CPP to have access to a struct, it has to be defined in CPP.