2019.2.19f1 : PropertyField changed event?

This is probably a nobrainer. I am trying to set a target object, and access available properties on that object. I'm trying to use UIElements for this.

Code (CSharp):

1.         public override VisualElement CreatePropertyGUI(SerializedProperty property)
2.         {
3.             Debug.Log("CreatePropertyGUI(...)");
4.  
5.             container = new VisualElement();
6.  
7.             var targetItemProperty = property.FindPropertyRelative("targetItem");
8.  
9.             var targetItemField = new PropertyField(targetItemProperty);
10.             container.Add(targetItemField);
11.  
12.             var selectedItem = targetItemProperty.objectReferenceValue as Item;
13.  
14.             if (selectedItem != null)
15.             {
16.                 var propertyList = selectedItem.SerializeProperties().Select(x => x.Name).ToList();
17.  
18.                 popupField = new PopupField<string>("label", propertyList, 0);
19.                 popupField.formatSelectedValueCallback += Selected;
20.  
21.                 container.Add(popupField);
22.             }
23.  
24.             return container;
25.         }

selectedItem is always null, no matter what I do.

Do I need to add a listener to the PropertyField like I do for the PopupField? How?

 

I'm probably too used to the IMGUI. CreatePropertyGUI is called only once when you switch to the corresponding Inspector. So how do I listen to a change in the property field correctly?

targetItemField.RegisterCallback<ChangeEvent<Item>>(i => PropertyCallback(i.newValue));

does not work.

 

Thanks, I'll try that. I don't understand the logic behind this. A PropertyField (no matter what type of property it is) is going to be changed. That's the whole point of having a property exposed to the inspector. So why not give it a changed event that someone can listen to?

 

Code (CSharp):

1. targetItemField = new PropertyField(targetItemProperty);
2. container.Add(targetItemField);
3. objectField = container.Query<ObjectField>().First();

or

Code (CSharp):

1.  
2. targetItemField = new PropertyField(targetItemProperty);
3. objectField = targetItemField.Query<ObjectField>().First();

objectField is always null.

 

I now resorted to adding an ObjectField like this. Then I can register my valuechangedcallback.

But now the PopupField never shows up in the Inspector.

Code (CSharp):

1.   public override VisualElement CreatePropertyGUI(SerializedProperty property)
2.         {
3.             container = new VisualElement();
4.  
5.             var targetItemProperty = property.FindPropertyRelative("targetItem");
6.  
7.             var objectField = new ObjectField(targetItemProperty.displayName);
8.             objectField.objectType = typeof(Item);
9.             objectField.bindingPath = targetItemProperty.propertyPath;
10.             objectField.BindProperty(property.serializedObject);
11.  
12.             objectField.RegisterValueChangedCallback(ObjectField_ValueChanged);
13.  
14.             container.Add(objectField);
15.  
16.             return container;
17.         }
18.  
19.         private void ObjectField_ValueChanged(ChangeEvent<UnityEngine.Object> e)
20.         {
21.             var previousValue =  e.previousValue as Item;
22.             var newValue = e.newValue as Item;
23.  
24.             if (newValue != null)
25.             {
26.                 var propertyList = newValue.SerializeProperties().Select(x => x.Name).ToList();
27.  
28.                 popupField = new PopupField<string>("Property", propertyList, 0);
29.                 popupField.formatSelectedValueCallback += Selected;
30.  
31.                 container.Add(popupField);
32.             }
33.         }

 

Ok with this code, the property popup list appears, but the ObjectField content is immediately reset to None.

I set the binding path for my object field, I call Bind. So why is the item that I drag & drop into the field not stored?

Plus: container.Remove(popupField); causes an exception: ArgumentException: This visualElement is not my child

Code (CSharp):

1. public override VisualElement CreatePropertyGUI(SerializedProperty property)
2.         {
3.             container = new VisualElement();
4.  
5.             var targetItemProperty = property.FindPropertyRelative("targetItem");
6.  
7.             var objectField = new ObjectField(targetItemProperty.displayName);
8.             objectField.objectType = typeof(Item);
9.             objectField.bindingPath = targetItemProperty.propertyPath;
10.             objectField.Bind(property.serializedObject);
11.             objectField.RegisterValueChangedCallback((e) => ObjectField_ValueChanged(e, property.serializedObject));
12.  
13.             container.Add(objectField);
14.  
15.             return container;
16.         }
17.  
18.         private void ObjectField_ValueChanged(ChangeEvent<UnityEngine.Object> e, SerializedObject serializedObject)
19.         {
20.             var previousValue =  e.previousValue as Item;
21.             var newValue = e.newValue as Item;
22.  
23.             if (newValue != null)
24.             {
25.                 var propertyList = newValue.SerializeProperties().Select(x => x.Name).ToList();
26.  
27.                 if(popupField != null)
28.                 {
29.                     container.Remove(popupField);
30.                 }
31.  
32.                 popupField = new PopupField<string>("Property", propertyList, 0);
33.                 popupField.formatSelectedValueCallback += Selected;
34.  
35.                 container.Add(popupField);
36.                 container.Bind(serializedObject);
37.             }
38.         }

 

I threw everything away and did it using IMGUI.

 

I too was wondering how to bind my custom list displayed in the PopupField to a propery.
I'm displaying a simple string value. and wanted to populate it based on values written in other scripts.

This displays the actionKey with standard layout, lable, value. When clicking the popup its value changes, which is good enough for me.

Code (CSharp):

1.  
2.  
3.             PropertyField actionKey = new PropertyField(property.FindPropertyRelative("actionKey"));
4.              rootContainer.Add(actionKey); // basically string.
5.  
6.             List<string> popupFieldValues = new List<string>();
7.             MissionEventMapper[] mappers = GameObject.FindObjectsOfType<MissionEventMapper>();
8.             foreach (var missionEventMapper in mappers)
9.             {
10.                 popupFieldValues.Add(""); // hoping theres a prop on PopupField to allow custom strings.
11.                 foreach (var missionEventItem in missionEventMapper.eventItems)
12.                 {
13.                     popupFieldValues.Add(missionEventItem.eventKey);
14.                 }
15.             }
16.  
17.             var popupField = new PopupField<string>(popupFieldValues, popupFieldValues[0]);
18.             popupField.BindProperty(property.FindPropertyRelative("actionKey"));
19.            rootContainer.Add(popupField);
20.  

 

I guess this is a good summary of current state of UTK as of now

 

I think the hardest bit is finding examples and tutorials that do things people actually want to do. Like, reorderable list. Its insane that Unity expect us to use 3rd party solutions for something this simple. I want to keep those to a minimum thanks.

Other than that, now that i've spent, admittedly, way too much time working this out, it's by far a much better solution than IMGUI. This is of course once you know things like, rootContainer.bind(serialisedObject) is key to getting things to display. And using the xml/uss to manage layout is super helpful, but you need to shift the way you think about structuring your code, for example building lists as a result of a changeevent rather than in OnEnable.

 

Is this even available at runtime?

 

Its in an editor script so no.

I imagine your refering to the use of Toolkit for ingame UI. I haven't played with that yet. Mostly using Toolkit for custom property inspectors, and when adding properties by hand (i.e. list recursion) i've found that unless you call rootContainer.bind(serialisedObject), nothing will appear.