Question How to check if IAspect has an optional component?

Hello!

I am trying to get started with Unity ECS and run into difficulties checking if an IAspect has an optional component. As far as I can tell I am supposed to use "_myOptionalComponent.IsValid" within the aspect struct to check if the component exists, however, even if I am fairly sure that the component should exist .IsValid always returns "False".

Consider this simple system:

Components:

Code (CSharp):

1.  
2. using Unity.Entities;
3.  
4. namespace Test
5. {
6.     public struct TestValueComponent : IComponentData
7.     {
8.         public int ValueWithTag;
9.         public int ValueWithoutTag;
10.     }
11.  
12.     public struct TestTag : IComponentData { }
13. }
14.  

Authoring + Baking:

Code (CSharp):

1.  
2. using Unity.Entities;
3. using UnityEngine;
4.  
5. namespace Test
6. {
7.     public class TestAuthoring : MonoBehaviour
8.     {
9.         public bool AddTestTag;
10.     }
11.  
12.     public class TestBaker : Baker<TestAuthoring>
13.     {
14.         public override void Bake(TestAuthoring authoring)
15.         {
16.             if (authoring.AddTestTag)
17.             {
18.                 AddComponent<TestTag>();
19.             }
20.  
21.             AddComponent(new TestValueComponent
22.             {
23.                 ValueWithTag = 0,
24.                 ValueWithoutTag= 1
25.             });
26.         }
27.     }
28. }
29. }
30.  

Aspect:

Code (CSharp):

1.  
2. using Unity.Entities;
3.  
4. namespace Test
5. {
6.     public readonly partial struct TestAspect : IAspect
7.     {
8.         private readonly RefRO<TestValueComponent> _testComponent;
9.  
10. // I think the problem is somewhere around here?
11.         [Optional] private readonly RefRO<TestTag> _testTag;
12.         public bool HasTag() => _testTag.IsValid;
13.  
14.         public int GetValueWithTag() => _testComponent.ValueRO.ValueWithTag;
15.  
16.         public int GetValueWithoutTag() => _testComponent.ValueRO.ValueWithoutTag;
17.     }
18. }
19.  

System + Job:

Code (CSharp):

1.  
2. using Unity.Burst;
3. using Unity.Entities;
4.  
5. namespace Test
6. {
7.     [BurstCompile]
8.     public partial struct TestSystem : ISystem
9.     {
10.         [BurstCompile]
11.         public void OnCreate(ref SystemState state) { }
12.  
13.         [BurstCompile]
14.         public void OnDestroy(ref SystemState state) { }
15.  
16.         [BurstCompile]
17.         public void OnUpdate(ref SystemState state)
18.         {
19.             new TestJob
20.             {
21.             }.ScheduleParallel();
22.         }
23.     }
24.  
25.     [BurstCompile]
26.     public partial struct TestJob : IJobEntity
27.     {
28.         [BurstCompile]
29.         private void Execute(ref TestAspect aspect)
30.         {
31.             if (aspect.HasTag())
32.             {
33.                 UnityEngine.Debug.Log(aspect.GetValueWithTag().ToString());
34.             }
35.             else
36.             {
37.                 UnityEngine.Debug.Log(aspect.GetValueWithoutTag().ToString());
38.             }
39.         }
40.     }
41. }
42.  

Then I create a new GameObject within an empty subscene and add the TestAuthoring script. Now, from what I understand, the moment I enter player I should get a lot of "0"s in the console when I have checked the "AddTestTag" checkbox on the TestAuthoring Gameobject and "1" if I didnt. However, in both cases, I only get "1"s, i.e. the aspect doesnt find the optional component even if the Inspector tells me that it is attached to the entity.

I am fairly sure that I am overlooking something really obvious here, but as it stands I am at my wit's end. Thanks in advance for your help!

 

Just from your code I don't see anything obvious.
Couples of questions :
Is your authoring component bool set to true in the editor ?
Have you tried to do the same thing with a non tag component?

 

Thanks, you found the problem!

It works when I change

Code (CSharp):

1. public struct TestTag : IComponentData { }

to

Code (CSharp):

1. public struct TestTag : IComponentData
2.     {
3.         public float ValueThatWillNeverBeUsed;
4.     }

So, I suppose optional tag components aren't supported?

 

I'm just going to bump this, since I've just ran into this unexpected behaviour myself and I believe it should either be fixed or at least documented.