My UStructs aren't being recognised.

anonymous_user_cd8511271 · August 9, 2016, 11:46am

Hello,

I’ve created a struct called ‘FItem’ and it stores some very basic variables, I’ve given it the USTRUCT() tag but whenever I create a variable of type FItem or, in my case, create an array of them with the UPROPERTY tag I get the error Error:

Unrecognized type ‘FItem’ - type must be a UCLASS, USTRUCT or UENUM

USTRUCT(BlueprintType)
struct FItem
{
	GENERATED_USTRUCT_BODY()

	UPROPERTY(EditAnywhere, BlueprintReadWrite, Category = "Inventory")
		int Id;

	UPROPERTY(EditAnywhere, BlueprintReadWrite, Category = "Inventory")
		FString Name;

	UPROPERTY(EditAnywhere, BlueprintReadWrite, Category = "Inventory")
		FString Description;
};

This is what it looks like in my actor component class:

	UPROPERTY()
	TArray<FItem> ItemDataBase;

Thanks in advanced.

Atheist91 · August 9, 2016, 1:34pm

If you declared that struct in other header than the one where you’re trying to use it as property, then you have to include the header containing the declaration of that struct.

For example if you declared your struct in MyHeaderWithStruct.h and you’re trying to make a property in MyActorComponent.h header, then you need to add this on top of your MyActorComponent.h file.

#include "MyHeaderWithStruct.h"

anonymous_user_cd8511271 · August 9, 2016, 1:37pm

Hello, thanks for your reply.

The headers were correct, I probably should have mentioned that before, although my stuct is not in it’s own header file, it’s below another class. The intellisense recognises ‘FItem’ and if I remove the UPROPERTY() there’s no error but I need it to be a UPROPERTY.

Atheist91 · August 9, 2016, 1:59pm

Okay then.

Change type of your Id variable to int32 (or something else that is supported by UPROPERTies).

anonymous_user_2b03d27c · August 9, 2016, 6:22pm

Hey TroyAtkinson-

Are you getting this error in Visual Studio when compiling or when trying to use the struct in the editor? I was able to copy the above struct into a class that compiled and was available in the editor. Can you provide additional information about your setup?

Atheist91 · August 9, 2016, 7:21pm

I just added your code to my project (with a change of Id to int32) and it works. O.o

Since your code in comment above doesn’t show where you exactly tried to use UPROPERTY and since you have array of items and array of pointers to items, then you should know that UPROPERTY doesn’t work with pointers to struct.

If that’s now what you wanted to do, then I guess we’ll have to keep thinking.

Atheist91 · August 9, 2016, 7:26pm

Okay, nvm. Just re- your comment.

anonymous_user_cd8511271 · August 9, 2016, 7:09pm

Hello , thanks for your reply.

I’m getting the error in the Unreal message log when it fails to compile. ‘Unrecognized type ‘FItem’ - type must be a UCLASS, USTRUCT or UENUM’. If I remove the UPROPERTY() tag it compiles. Would you recommend I make a new header file just for the struct?

anonymous_user_cd8511271 · August 9, 2016, 7:11pm

Hi again, I updated it to int32 and I’m getting the same error.

anonymous_user_cd8511271 · August 9, 2016, 7:14pm

This is the first header file with the struct.

UCLASS(Blueprintable, BlueprintType)
class GAMENAME_API UGameSingleton : public UObject
{
	GENERATED_BODY()

public:
	// TODO - Get rid of this if it's not used
	UGameSingleton(const FObjectInitializer& ObjectInitializer);

	// Inventory
	UPROPERTY(EditAnywhere, BlueprintReadWrite, Category = "Inventory")
		class UPlayerInventory* PlayerInventory;
};

// TODO - Put this in it's own header file
USTRUCT(BlueprintType)
struct FItem
{
	GENERATED_USTRUCT_BODY()

	UPROPERTY(EditAnywhere, BlueprintReadWrite, Category = "Inventory")
		int32 Id;

	UPROPERTY(EditAnywhere, BlueprintReadWrite, Category = "Inventory")
		FString Name;

	UPROPERTY(EditAnywhere, BlueprintReadWrite, Category = "Inventory")
		FString Description;
};

And this is the class that uses the struct

#pragma once
#include "Components/ActorComponent.h"
#include "GameSingleton.h"
#include "PlayerInventory.generated.h"

UCLASS( ClassGroup=(Custom), Blueprintable, BlueprintType, meta=(BlueprintSpawnableComponent) )
class GAMENAME_API UPlayerInventory : public UActorComponent
{
	GENERATED_BODY()
public:
	// Functions & constructors
	UPlayerInventory();
	virtual void BeginPlay() override;
	void AddInstanceToGameSingleton();

	UFUNCTION(BlueprintNativeEvent, BlueprintCallable, Category = "Inventory")
	void CreateItems();
	void CreateItems_Implementation();

	UFUNCTION(BlueprintCallable, Category = "Inventory")
	void CreateItem(FString ItemName, FString ItemDescription);

	// Variables & properties
	TArray<struct FItem> ItemDataBase;
	int32 NumberOfDatabaseItems;

	TArray<struct FItem*> Items;
};

On Line 24 is where I’m creating the Array of FItems, right now I’ve taken the UPROPERTY() prefix off so it doesn’t error. But as soon as I put it on it doesn’t compile.

anonymous_user_2b03d27c · August 9, 2016, 7:21pm

Structs need to be placed outside of the class declaration for whatever class it is added to. If your struct is inside the declaration, try copying it to just below the header’s include statements. Putting the struct would be another solution however it shouldn’t be necessary.

anonymous_user_cd8511271 · August 9, 2016, 7:30pm

Sorry I didn’t mentioned where the UPROPERTY went, it was line 24. Could you try this code, it still doesn’t compile with the same error coming from line 25, if it works fine for you then I’m just going start a new project.

Edit: there was a mistype but I fixed it and it still comes up with the error.

#pragma once
#include "Components/ActorComponent.h"
#include "GameSingleton.h"
#include "PlayerInventory.generated.h"

UCLASS( ClassGroup=(Custom), Blueprintable, BlueprintType, meta=(BlueprintSpawnableComponent) )
class GAMENAME_API UPlayerInventory : public UActorComponent
{
	GENERATED_BODY()
public:
	// Functions & constructors
	UPlayerInventory();
	virtual void BeginPlay() override;
	void AddInstanceToGameSingleton();

	UFUNCTION(BlueprintNativeEvent, BlueprintCallable, Category = "Inventory")
	void CreateItems();
	void CreateItems_Implementation();

	UFUNCTION(BlueprintCallable, Category = "Inventory")
	void CreateItem(FString ItemName, FString ItemDescription);

	// Variables & properties
	UPROPERTY()
	TArray<struct FItem> ItemDataBase;
	int32 NumberOfDatabaseItems;

	//TArray<struct FItem*> Items;
};

// TODO - Put this in it's own header file
USTRUCT(BlueprintType)
struct FItem
{
	GENERATED_USTRUCT_BODY()

	UPROPERTY(EditAnywhere, BlueprintReadWrite, Category= "Inventory")
		int32 ItemId;

	UPROPERTY(EditAnywhere, BlueprintReadWrite, Category = "Inventory")
		FString Name;

	UPROPERTY(EditAnywhere, BlueprintReadWrite, Category = "Inventory")
		FString Description;
};

anonymous_user_cd8511271 · August 9, 2016, 7:45pm

It works, you’re my hero. I can’t thank-you enough
Re-reading what said, yeah it’s pretty much the same but I didn’t take out of it what I needed.

Have a great day, thanks again!

Atheist91 · August 9, 2016, 7:41pm

Okay, now I have this issue.

The solution to fix it, is just to switch place of your class declaration and struct declaration. Every class/struct you use, has to be declared first, before you can use it. (i’m not totally sure if that’s what meant, so sorry if i’m simply saying that same what you said :p)

I see you tried to use forward declaration there, but it looks like it doesn’t work with structs and UPROPERTies (i just tested it). Odd.

@Down:
Yw, happy coding!

anonymous_user_cd8511271 · August 9, 2016, 7:46pm

It’s working, big thanks

Have a great day!