Bind to nested properties

Version: 2021.3+

This example demonstrates how to use the binding-path attribute of a BindableElement in UXML to bind fields to nested properties of a SerializedObject.

Example overview

This example creates a custom Inspector UI with the following:

• Two fields that bind to a GameObject’s name and the scale of a USS transform
• Two fields that bind to nested properties of a SerializedObject

You can find the completed files that this example creates in this GitHub repository.

先决条件

This guide is for developers familiar with the Unity Editor, UI Toolkit, and C# scripting. You are recommended to have a basic understanding of the following:

• Visual Tree
• UXML
• USS
• BindableElement
• PropertyField

Create the destructible tank object

Create a C# script to define a class for a tank that has health values to make it destructible.

1. Create a project in Unity with any template.

2. In your Project window, create a folder named bind-nested-properties to store all the files.

3. Create a C# script named DestructibleTankScript.cs and replace its content with the following:

   using System;
   using UnityEngine;
   using UnityEngine.Serialization;
   
   [Serializable]
   public struct Health
   {
       public int armor;
       public int life;
   }
   
   [ExecuteInEditMode]
   public class DestructibleTankScript : MonoBehaviour
   {
       public string tankName = "Tank";
       public float tankSize = 1;
   
       public Health health;
   
       private void Update()
       {
           gameObject.name = tankName;
           gameObject.transform.localScale = new Vector3(tankSize, tankSize, tankSize);
       }
   
       public void Reset()
       {
           health.armor = 100;
           health.life = 10;
       }
   }
   

Create the UXML and the Inspector UI

Create a UXML file with a BindableElement. Set the BindableElement’s binding-path to the health property and set each child element’s binding-path of the BindableElement to the armor and life properties of health.

1. In the bind-nested-properties folder, create a folder named Editor.

2. In the Editor folder, create a USS file named tank_inspector_styles.uss and replace its contents with the following:

   .container {
       background-color: rgb(80, 80, 80);
       flex-direction: column;
   }
   Label {
       background-color: rgb(80, 80, 80);
   }
   TextField:hover {
       background-color: rgb(255, 255, 0);
   }
   FloatField {
       background-color: rgb(0, 0, 255);
   }
   

3. Create a UI Document named destructible_tank_editor.uxml and replace its contents with the following:

   <UXML xmlns="UnityEngine.UIElements" xmlns:ue="UnityEditor.UIElements">
       <Style src="tank_inspector_styles.uss"/>
       <VisualElement name="row" class="container">
           <Label text="Tank Script - Custom Inspector" />
           <ue:PropertyField binding-path="tankName" name="tank-name-field" />
           <ue:PropertyField binding-path="tankSize" name="tank-size-field" />
           <BindableElement binding-path="health">
               <ue:PropertyField binding-path="armor"/>
               <ue:PropertyField binding-path="life"/>
           </BindableElement>
       </VisualElement>
   </UXML>
   

Create the custom Editor

Create a C# script that registers a custom Editor for the DestructibleTankScript.

1. Create a C# script named DestructibleTankEditor.cs and replace its content with the following:

   using UnityEditor;
   using UnityEngine;
   using UnityEngine.UIElements;
   
   [CustomEditor(typeof(DestructibleTankScript))]
   public class DestructibleTankEditor : Editor
   {
       [SerializeField]
       VisualTreeAsset visualTreeAsset;
   
       public override VisualElement CreateInspectorGUI()
       {
           return visualTreeAsset.CloneTree();
       }
   }
   

2. Select DestructibleTankEditor.cs in the Project window.

3. Drag destructible_tank_editor.uxml to Visual Tree Asset in the Inspector.

Test the binding

1. In Unity, add an empty GameObject to a scene.
2. Select the GameObject.
3. Add the Destructible Tank Script component in the Inspector. The Armor and Life fields are bound to the health.armor and health.life properties. If you change the values in the Inspector, the values of the underlying properties change.

其他资源

• SerializedObject data binding
• Bindable elements
• Binding data type conversion
• Implementation details
• Binding examples