Why does my custom DropdownField not bind?

Unity Engine
,
1

I have created a custom DropdownField which seems to work. Except that I get a strange error:

Field type Editor.Elements.PetDropdownField is not compatible with PPtr<$Pet> property “pet”
UnityEditor.InspectorWindow:RedrawFromNative ()

and the DropdownField does not seem to bind to the object.

DropdownField

using System.Collections.Generic;
using Scripts;
using UnityEngine;
using UnityEngine.UIElements;

namespace Editor.Elements
{
    public class PetDropdownField : PopupField<Pet>
    {
        public new class UxmlTraits : BaseField<Pet>.UxmlTraits { }

        public new class UxmlFactory : UxmlFactory<PetDropdownField, UxmlTraits> { }
     
        private static List<Pet> Choices() => new(Resources.LoadAll<Pet>("Pets"));

        public PetDropdownField() : base(
            "Pets",
            Choices(),
            -1,
            s => s?.name ?? "unknown",
            s => s?.name ?? "unknown"
        ) { }
    }
}

Scriptable Objects

using UnityEngine;

namespace Scripts
{
    [CreateAssetMenu(fileName="new Owner", menuName="Owner")]
    public class Owner : ScriptableObject
    {

        [SerializeField] private Pet pet;

    }
}

namespace Scripts
{
    [CreateAssetMenu(fileName="new Pet", menuName = "Pet")]
    public class Pet : ScriptableObject
    {
     
    }
}

Editor

using Scripts;
using UnityEditor;
using UnityEngine;
using UnityEngine.UIElements;

namespace Editor
{
 
    [CustomEditor(typeof(Owner))]
    public class OwnerEditor : UnityEditor.Editor
    {

        [SerializeField] private VisualTreeAsset template;

        public override VisualElement CreateInspectorGUI() => template.CloneTree();

    }
}

<ui:UXML xmlns:ui="UnityEngine.UIElements" xmlns:uie="UnityEditor.UIElements" xsi="http://www.w3.org/2001/XMLSchema-instance" engine="UnityEngine.UIElements" editor="UnityEditor.UIElements" noNamespaceSchemaLocation="../../../UIElementsSchema/UIElements.xsd" editor-extension-mode="False">
    <Editor.Elements.PetDropdownField label="Pet" binding-path="pet" />
</ui:UXML>

Does anyone know why this control does not bind?

8435858--1117430--dropdown2.png
8435858--1117430--dropdown2.png1003×469 46.1 KB

2

Hello! Your control should inherit from PopupField<Object> instead of PopupField<Pet> so the binding system can detect it. Basically:

DropdownField

    using System.Collections.Generic;
    using Scripts;
    using UnityEngine;
    using UnityEngine.UIElements;
    
    namespace Editor.Elements
    {
        public class PetDropdownField : PopupField<Object>
        {
            public new class UxmlTraits : BaseField<Object>.UxmlTraits { }
    
            public new class UxmlFactory : UxmlFactory<PetDropdownField, UxmlTraits> { }
        
            private static List<Object> Choices() => new(Resources.LoadAll<Pet>("Pets"));
    
            public PetDropdownField() : base(
                "Pets",
                Choices(),
                -1,
                s => s?.name ?? "unknown",
                s => s?.name ?? "unknown"
            ) { }
        }
    }

That should do it :slight_smile: