String in custom element is null

Unity Engine
,
1 
using UnityEngine;
using UnityEngine.UIElements;

[UxmlElement]
public partial class TestVisualElement : VisualElement
{
    [UxmlAttribute]
    public string TestString { get; set; }

    public TestVisualElement()
    {
        Debug.Log(TestString);
    }
}

9845655--1416984--upload_2024-5-20_23-16-42.png

9845655--1416975--upload_2024-5-20_23-14-54.png
9845655--1416975--upload_2024-5-20_23-14-54.png991Ă—134 22.4 KB

Why?

2

The value is applied after the element is constructed, there’s no way we could do it before. You can use the property setter method to know when its set.

2 Likes
3

Ok this seems to work

using UnityEngine;
using UnityEngine.UIElements;

[UxmlElement]
public partial class TestVisualElement : VisualElement
{
    [UxmlAttribute]
    public string TestString { get; set; }

    public TestVisualElement()
    {
        RegisterCallback<AttachToPanelEvent>(OnAttachToPanel);
    }

    void OnAttachToPanel(AttachToPanelEvent evt)
    {
        Debug.Log(TestString);
    }
}

9845730--1417005--upload_2024-5-20_23-55-54.png

4

When I use this custom element directly in UI Document it works fine but if I make a template from it and use this template inside the document it returns null again

5

Ok seems like using setter works fine in all cases, thanks

1 Like
6

Got new problem. The property gets reseted for some reason in this code:

[UxmlElement]
public partial class KeyBindingView : VisualElement
{
    [UxmlAttribute]
    public string ActionName
    {
        get => _actionName;
        set
        {
            _actionName = value;
            Debug.Log("PROP: " + _actionName);
        }
    }

    private string _actionName;

    private Label KeyBindingNameLabel;
    private Button KeyBindingPrimaryActionButton;
    private Button KeyBindingSecondaryActionButton;

    public void Initialize()
    {
        Debug.Log("INIT");
        KeyBindingNameLabel = this.Q<Label>("key-binding__name-label");
        KeyBindingPrimaryActionButton = this.Q<Button>("key-binding__action-button-primary");
        KeyBindingSecondaryActionButton = this.Q<Button>("key-binding__action-button-secondary");

        InputAction action = InputSystem.actions.FindAction(ActionName);

        KeyBindingNameLabel.text = ActionName;
        KeyBindingPrimaryActionButton.text = action.bindings[0].ToDisplayString();
        KeyBindingSecondaryActionButton.text = action.bindings[0].ToDisplayString();
    }
}

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9849168--1417854--upload_2024-5-22_16-56-24.png
9849168--1417854--upload_2024-5-22_16-56-24.png981Ă—77 5.46 KB

7

Thats normal, it resets values in the UI Builder.
You should adjust your code to expect a null string or change the default value for _actionName.
Maybe change it to private string _actionName = "";

8

I’m not sure I understand how private string _actionName = ""; should help.
I want to configure different strings for each instance of KeyBindingTemplate but it resets all of them to value of _actionName.

9

The UI Builder will set all the attributes to their default values. The default value for ActionName is currently null. Instead of setting it to “” you would be better checking if the value is null or empty in Initialize and not calling InputSystem.actions.FindAction if it is.

10

I mean, yeah, there will be no error if I check for null or empty but property is initialized with configured in UIBuilder string and after that gets reseted to default value. So at the end all instances reseted to whatever _actionName is.
This is what I have in Builder:
9849330--1417893--upload_2024-5-22_18-16-58.png
It’s properly initialized at start
9849330--1417896--upload_2024-5-22_18-17-25.png
After that it gets reseted without calling property setter
9849330--1417902--upload_2024-5-22_18-19-44.png

11

I think it’s a bug or I don’t know something about templates. My uxml structure looks like this:
9856578--1419537--upload_2024-5-27_3-6-46.png
Everything is fine but if I give SettingsWindow.uxml template some name all properties in custom controls inside it will fail to initialize.
Without name:
9856578--1419540--upload_2024-5-27_3-9-53.png
With name:
9856578--1419543--upload_2024-5-27_3-10-50.png9856578--1419546--upload_2024-5-27_3-11-13.png
What could be the reason for this behavior?

12

Made bug report just in case (IN-77201)

13

Just got update that this bug is fixed in 6000.0.7f1