Adding Meta to Blueprint Variables

Development Programming & Scripting Blueprint
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1

Hey guys,

Is it possible to add properties to Blueprint variables in the editor?
I want to add a flag that indicates whether a value should be database serialised and another flag that indicates if a value should be included in debugging information, but so far it’s been elusive to add meta properties!

Cheers,
Calem

2

Hi! You can use custom metadata with functions, classes and properties till you using C++ code. To use this you have to add your custom meta directly to UCLASS\UPROPERTY\UFUNCTION Meta block

UPROPERY(Meta="MyCustomMeta=100500")

This meta value will be attached to the property and you will be able to get it using UProperty::GetMeta or check presence of a meta flag using UProperty::HasMeta. To extract meta from object instance you can use GetClass() first. It will give you a reference to the Class object associated with your c++ class. This object contains functions like FindProperty, which allow to find a property by it’s name. If you get UProperty reference somehow it’s easy to get an associated meta - UProperty references contain GetMeta function.

UClass* CheckClass = SomeUObject.GetClass();
UProperty* CheckProperty = CheckClass.FindProperty(TEXT("SomeProperty"));
FString CustomMeta = CheckProperty.GetMeta(TEXT("CustomMeta"));
3

thanks for the answer! i’ve clarified my question a bit since i realised i only put editor in the tags. do you know if it’s possible to add meta to properties that are variables in blueprints in the editor?

4

Unfortunately I have no idea how to use custom meta without c++. If you don’t have a c++ based module in your project I even have no idea how do you want to make a custom serialization. (There is no exposed to the blueprint serializers as I know). If you have a c++ module but just want to mark fields directly from the blueprint editor you can use blueprint details modifiers. They affects all blueprints but they should be registered from the c++ code too.

	// Register Blueprint editor variable customization
	FBlueprintEditorModule& BlueprintEditorModule = FModuleManager::LoadModuleChecked<FBlueprintEditorModule>("Kismet");
	BlueprintEditorModule.RegisterVariableCustomization(UProperty::StaticClass(), FOnGetVariableCustomizationInstance::CreateStatic(&FControlRigVariableDetailsCustomization::MakeInstance));

Example of how it works you can find in the engine sources: UE_4.17\Engine\Plugins\Experimental\ControlRig\Source\ControlRigEditor\Private\ControlRigVariableDetailsCustomization.cpp

This modifier adds some extra checkers for some variables and extends meta like you want to do.

5

Doesn’t seem to be possible right now.

Edit: asking this elsewhere, hoping for updates soon!