Resolved RefRW<LocalTransform> : Local Transform Component missing from Entity

Diving into entities by following along with a tutorial and making updates where required.

ArgumentException: A component with type:Unity.Transforms.LocalTransform has not been added to the entity.

I get the above exception when trying to reference the LocalTransform component to my aspect. This LocalTransform should be on every entity right?

Code (CSharp):

1.     public readonly partial struct SpawnerAspect : IAspect
2.     {
3.         public readonly Entity Entity;
4.  
5.         private readonly RefRO<SpawnerProperties> _properties;
6.  
7.         private readonly RefRW<LocalTransform> _transform;
8.         private readonly RefRW<RandomComponent> _random;
9.  
10.         public int EnemiesToSpawn => _properties.ValueRO.EnemiesToSpawn;
11.         public Entity EnemyPrefab => _properties.ValueRO.EnemyPrefab;
12.  
13.     }

Some more investigating shows that on Play, the entity is not getting a Local Transform Component

 

To add, documentation on transforms has this paragraph

The built-in transform system adds a LocalTransform component to each entity by default. It stores the data that represents an entity's position, rotation, and scale. There are also a variety of static helper methods defined on it.

 

Entities don't always have LocalTransform, this is configurable when baking.
Prefabs are currently always baked with a LocalTransform.
https://docs.unity3d.com/Packages/com.unity.entities@1.0/api/Unity.Entities.IBaker.GetEntity.html
https://docs.unity3d.com/Packages/com.unity.entities@1.0/api/Unity.Entities.TransformUsageFlags.html
Entities needing transforms should have a baker specify TransformUsageFlags.Dynamic so the framework knows a transform is needed and adds one.

 

Solved! Thank you! The TransformUsageFlags I wasn't too knowledgeable on and had them in my Bake as None but this helped me understand a bit about how things are getting baked. My Bake code now looks like this,

Code (CSharp):

1.     public class SpawnerBaker : Baker<SpawnerMono>
2.     {
3.         public override void Bake(SpawnerMono authoring)
4.         {
5.             Entity entity = GetEntity(TransformUsageFlags.Dynamic);
6.             AddComponent(entity, new SpawnerProperties
7.             {
8.                 FieldDimensions = authoring.FieldDimensions,
9.                 EnemiesToSpawn = authoring.EnemiesToSpawn,
10.                 EnemyPrefab = GetEntity(authoring.EnemyPrefab, TransformUsageFlags.None)
11.             });
12.  
13.             AddComponent(entity, new RandomComponent
14.             {
15.                 RandomGenerator = Unity.Mathematics.Random.CreateFromIndex(authoring.RandomSeed)
16.             });
17.         }
18.     }

This line was changed from

Entity entity = GetEntity(TransformUsageFlags.None);

to:

Entity entity = GetEntity(TransformUsageFlags.Dynamic);