Data Asset: Only allow an int var to be positive

Development Programming & Scripting C++
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1

Fairly simple question, but I can’t tell if I’m just not finding documentation or if I shouldn’t be trying to do this in the first place.

In my C++ UDataAsset, I have the uproperty:

int32 NumPages = 100;

I want to make sure the input for this data asset is always positive using a MakePositive function (which is already written.)

But… how do I do that? Is it even a good idea to do that or is this not how a data asset is intended to work?

2

If you’re trying to limit the value of NumPages to only positive values while modifying it in the edttor, you can use the meta property ClampMin to set a minimum value.

UPROPERTY(EditAnywhere, BlueprintReadOnly, meta=(ClampMin=0))
int32 NumPages = 100;

There’s also the PostEditChangeProperty function that you can override to do operations on the value after it was edited.

#if WITH_EDITOR
void PostEditChangeProperty(FPropertyChangedEvent& PropertyChangedEvent) override;
#endif

#if WITH_EDITOR
void ASomeActor::PostEditChangeProperty(struct FPropertyChangedEvent& PropertyChangedEvent)
{
  Super::PostEditChangeProperty(PropertyChangedEvent);

  FName PropertyName = (PropertyChangedEvent.Property != NULL) ? PropertyChangedEvent.Property->GetFName() : NAME_None;
  if (PropertyName == GET_MEMBER_NAME_CHECKED(ASomeActor, NumPages)) 
  {
    if (NumPages < 0) 
    {
        MakePositive();
    }
  }
}
#endif

^ modified code from: