Reference a blueprint in C++ (Connect Pin Error)

[pynion]

Heya,

	public:
		/** Please add a variable description */
		UPROPERTY(BlueprintReadWrite, EditAnywhere, meta=(DisplayName="Affliction"))
		TSubclassOf<class UObject> AfflictionClass;

I have a C++ Struct, that I’m trying to add a complex blueprint reference to (to get it to work while i convert the entire thing to C++)

So, I’m trying to use the BreakStruct node to convert it to blueprint but get this.

I’ve tried referancing the parent (Object Class), among a few other trials, but nothing seems to get it to connect.

Does anyone know how to get through this?

[Roy_Wierer.Seda145]

The problem here is that your struct is using UObject as AfflictionClass, while the method GetEffect takes BPAfflictionClass and not UObject.

Easiest way to explain it is “an apple is a fruit, but a fruit is not an apple”, an AfflictionClass can be a UObject, but not the other way around. You should create a new c++ class “UAfflicationClass” and make that blueprint BPAfflicationClass inherit from it (by setting the parent class on the editor panel). In your c++ struct instead of using UObject for the property you use UAfflicationClass. Update the variables / parameters to accept that c++ class as input.

[pynion]

Thanks for the reply Roy! It’s making more sense on what was going wrong, I’m a step closer (I think) but the last bit both in blueprints and my mind isn’t connecting.

So the updated structure is now:

		/** Please add a variable description */
		UPROPERTY(BlueprintReadWrite, EditAnywhere, meta=(DisplayName="Affliction"))
		TSubclassOf<UAfflictionLink> AfflictionLink;

Which is beginning to make sense. Knowing that C++ can’t communicate with blueprints, having this file that they both can reference is a dot connected. But the I’m really unsure what I’m missing to get this to connect.

Here’s the new C++ parent class.

#pragma once

#include "CoreMinimal.h"
#include "AfflictionLink.generated.h"

/**
 * 
 */
UCLASS( Blueprintable)
class XXX_API UAfflictionLink : public UObject
{
	GENERATED_BODY()
	
};

Here’s where the blueprint stands…

And where the BP is parented

Thanks for the gander.

[Roy_Wierer.Seda145]

What remains is that the data type of parameter Affliction on the method GetAffliction should be updated to be the c++ class you made, else you have the same problem as I described with the UObject.

[Roy_Wierer.Seda145]

You should probably also add the specifier “BlueprintType” to the UCLASS:

Class Specifiers | Unreal Engine 4.27 Documentation

[pynion]

Thank you so very much Roy. I was not getting the connection, that I could replace the blueprint reference to my CPP for the input.

Here was my final issue.

[pynion]

Dang it. I thought I understood. But I still can’t seem to get the data from the struct. In my head I thought it was pulling from the parent struct and it built the connections from there. but getting the functions out of the original BP is still an issue. I can call them from BP itself, but when I used the LINK it doesn’t have them. I assume it’s because I don’t have them defined in my AfflictionLink.h, but my worry is that if I put them in the link, the names will show up and connect just fine but the functionality won’t be there.

)

Sorry, thought I understood =/

[pynion]

Update: I did go ahead and put it into the AfflictionLink.H It does connect with the gameplay tags.

{
	GENERATED_BODY()
	
	public:
	/** Removes Affliction */
	UPROPERTY(BlueprintReadWrite, EditAnywhere, Category="Application", meta=(MultiLine="true"))
	FGameplayTagContainer RemoveAfflictionWithTags;

	
};

But I’m wary that this is best practice?
Thanks for the help, I should be done with construction in the next few days and will will remember to post back!

[Roy_Wierer.Seda145]

If you wish to call any of the methods, or access data through that c++ class then you must first port what you implemented in Blueprint to c++. This is the correct way to do it though, just port it all one by one.

I think you are also mixing up something else here. You are accessing data from the class default on that image. I think you might want to access data from an object instance instead? If you don’t know the difference between a class and an instance it is important to look for a tutorial about that asap.

[pynion]

Thanks so much for support Roy, I’ll go brush up on object instancing. Converting a project to C++ from BP has been an immense learning experience. I appreciate your help!

[Roy_Wierer.Seda145]

This shows the difference quite well:

https://youtu.be/TL4c6vsbgMY?t=1147

In Blueprint a class pin is purple and an instance is a blue pin.