Unity ECS : System does not find entities

Question

I am having a problem with Unity ECS. My system does not find my entity with its query. This is my setup : I am currently testing with just one entity, that is created by a prefab, using this function :

Entity CreateEntity => GameObjectConversionUtility.ConvertGameObjectHierarchy(_parameters.carPrefab, _conversionSettings);

with

_assetStore = new BlobAssetStore();
_conversionSettings = GameObjectConversionSettings.FromWorld(World.DefaultGameObjectInjectionWorld, _assetStore);

My entity gets created properly (as i guess based on the entity window) :

My system uses this query :

Entities.ForEach((DynamicBuffer<EdgeBufferElement> pathBuffer, ref Translation position,
                ref Rotation rotation, ref CarComponentData car) => {
     //logic
}).Schedule(inputDeps);

But my system logic does not get executed. This is propably because the system shows that it can not find the entity :

I also tried to change the query to just reference the Translation but that lead to the same result. Do you have any idea what is going wrong here ?

Thanks for the help in advance !

Answer 1

This is because entities with Prefab tags are ignored in queries by default (you can easily override this ofc).

This promotes "prefab entity" pattern as calling EntityManager.Instantiate( prefab_entity ) is A LOT faster than EntityManager.Instantiate( prefab_gameObject )

using Unity.Entities;
using Unity.Jobs;
public class LetsTestQuerySystem : SystemBase
{
    protected override void OnCreate ()
    {
        Entity prefab = EntityManager.CreateEntity( typeof(Prefab) , typeof(MyComponent) );
        Entity instance = EntityManager.Instantiate( prefab );// Instantiate removes Prefab tag
        EntityManager.SetName( prefab , "prefab" );
        EntityManager.SetName( instance , "instance" );
    }
    protected override void OnUpdate ()
    {
        Entities
            // .WithAll<Prefab>()// query prefabs only
            .ForEach( ( ref MyComponent component ) => component.Value += 1 )
            .WithBurst().ScheduleParallel();
    }
    struct MyComponent : IComponentData { public int Value; }
}