PostEditChangeProperty: `FNAME` of FVector property or its components

Development Programming & Scripting
1

I set up an event handler for the PostEditChangeProperty. I use

const auto Name = PropertyChangedEvent.Property->GetFName();

to get the FName of the affected property and I use

static const FName FNameSomeProp = GET_MEMBER_NAME_CHECKED(USplineComponent, SomeProp);

to then go on and check

if(Name = FNameSomeProp) // ...

So far so great. However, one of my properties is an FVector Velocity. My variable Name has the value “X”, “Y”, or “Z”, depending on which component I edit in the editor.

GET_MEMBER_NAME_CHECKED(USplineComponent, Velocity.X) gives the more reasonable “Velocity.X”.

How do I go about it? Property doesn’t seem to have a function that gives a fully qualified name. The GetFName function gives a very incomplete name that won’t work anymore as soon as I add another FVector property.

2

For structs try PostEditChangeChainProperty .
Inside of the overridden function do something like:

#if WITH_EDITOR
void UYourAwesomeClass::PostEditChangeChainProperty(
    FPropertyChangedChainEvent& PropertyChangedEvent)
{
    Super::PostEditChangeChainProperty(PropertyChangedEvent);
    const FName PropertyName = PropertyChangedEvent.GetPropertyName();
    
    if (PropertyName == GET_MEMBER_NAME_CHECKED(UYourAwesomeClass, YourProperty))
    {
        
    }
}
#endif
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3

You pointed me into the right direction. Some details, though:

  • PostEditChangeChainProperty is a generalized form; they always fire both
  • GetPropertyName still only gives me X, I need
const auto Name = PropertyChangedChainEvent.PropertyChain.GetHead()->GetValue()->GetFName();
  • … to get the FName of my FVector property, and
const auto Tail = PropertyChangedChainEvent.PropertyChain.GetTail()->GetValue()->GetFName();
  • … to get the FName of members inside FVector (or any other struct).
  • For members that aren’t structs, Name and Tail are identical and give the simple property FName

None of this is documented. Luckily Rider has introspection.

2 Likes
4

I’ve never used GetHead or GetTail before, good to know how that works :+1:

I have seen that I can actually use this for structs :sweat_smile:

const FName PropertyName =
        PropertyChangedEvent.PropertyChain.GetActiveMemberNode()->GetValue()->GetFName();
1 Like