Question Default values of inherited fields not shown in UI Builder

When I add a standard UIElement "Button" into the hierarchy in the UI Builder, it fills the Text-Field with the default value "Button".

Then I wrote an Class "ButtonTranslatable" that inherits form the UIElement Button and adds a new attribute "TranslationKey".
When I add this "ButtonTranslatable" into the hierarchy in the UI Builder the Value of the Text Field is empty.

I just wrote it like described here
https://docs.unity3d.com/2019.1/Documentation/Manual/UIE-UXML.html
But instead of VisualElement I inherited form Button.

 

For the standard elements, UI Builder is setting default attributes when you add them in from the Library panel:

Code (CSharp):

1. new BuilderLibraryTreeItem("Button", nameof(Button), typeof(Button), () => new Button { text = "Button" })

This is why it has a default text value of "Button", the default values are being added by UI Builder, not in UI elements.

If you want your

ButtonTranslatable

class to have a default value for the existing text attribute, you'll need to set it in the

Init

method for its

UxmlTraits

:

Code (CSharp):

1.     public class ButtonTranslatable : Button
2.     {
3.         public new class UxmlFactory : UxmlFactory<ButtonTranslatable, UxmlTraits> { };
4.  
5.         public new class UxmlTraits : Button.UxmlTraits
6.         {
7.             public override void Init(VisualElement ve, IUxmlAttributes bag, CreationContext cc)
8.             {
9.                 base.Init(ve, bag, cc);
10.  
11.                 ButtonTranslatable buttonTranslatable = ve as ButtonTranslatable;
12.                 buttonTranslatable.text = "Translated Button";
13.             }
14.         };
15.     }

 

Unfortunatelly this would override any value of the "text"-attribute in an uxml file to "Translated Button".

But I you are correct with you first sentence:
When I drag a "Button" into the Hierarchy it adds "<ui:Button text="Button" />" to the uxml file.
But when I drag a "ButtonTranslatable" into the Hierarchy it only adds "<ButtonTranslatable />".

So is there a way to modify that behavior? Is there a way to add a custom "new BuilderLibraryTreeItem()" entry somewhere?
Which leads to another question: Is there a way to change the icon of a custom UiElement in the UI Builder?

 

Ah that's true, my bad.

Looking through the UI Builder code some more, it seems like it's calling the

Create

method in the factory when it's running

BuilderLibraryTreeItem

for custom classes.

I tried setting the default attributes in this method, but it was still resetting the attributes to the hard-coded value whenever UI Builder changed.

Instead, using

Create

, you may be able to achieve the desired result by checking whether the attribute has any value, then setting a value on it:

Code (CSharp):

1. public new class UxmlFactory : UxmlFactory<ButtonTranslatable, UxmlTraits> {
2.     public override VisualElement Create(IUxmlAttributes bag, CreationContext cc)
3.     {
4.         VisualElement visualElement = base.Create(bag, cc);
5.  
6.         Button button = visualElement as Button;
7.  
8.         if (button.text.Length == 0)
9.             button.text = "Translated Button";
10.  
11.         return visualElement;
12.     }
13. };

Unfortunately this also has its drawbacks, as it will actually set it back to the hardcoded value if the text is made blank at any point. It's not ideal, and there may be a cleaner or better way to do it, but hopefully it works for now.

Unfortunately not, as far as I can see. The code in UI builder that is running

BuilderLibraryTreeItem

for custom elements is passing "CustomCSharpElement" in as the

iconName

.

 

Any updates on this issue?