Entity Query for ISystems and SystemBase in Unity ECS 1.0

Question

I have a tile based building game in Unity ECS 1.0, where I add particular IComponentData to several systems. From a PlayerInput which is a MonoBehavior (because PlayerInput and InputActions are not translated to ECS), I tried to query all systems having that IComponentData. But I found that regular EntityQueries do not match for Entity representation of systems, so I had to use EntityManager.UniversalQueryWithSystems, which returns the Entity representation of all systems. There I do a for loop and check all systems for that particular component. Does anybody know if there is a more performant way to check for these components on systems? I already tried to return EntityManager.UniversalQueryWithSystems.ToComponentDataArray<MyComponent>(), but then it's complaining, that the query have not been initialized using this component (which of course I may not change, as it's not my own query).

Answer 1

I just found it. You can pass options to an EntityQueryBuilder or a call to SystemAPI.Query<>(..) with the method .WithOptions(..) then just pass EntityQueryOptions.IncludeSystems.

So a complete call could look like this:

public static NativeArray<Entity> GetSystemsManaged<T>() where T : struct, IComponentData
{
    if (World.DefaultGameObjectInjectionWorld == null
        || !World.DefaultGameObjectInjectionWorld.IsCreated
        || World.DefaultGameObjectInjectionWorld.EntityManager == null)
    {
        return new NativeArray<Entity>(0, Allocator.Temp);
    }
    EntityManager entityManager = World.DefaultGameObjectInjectionWorld.EntityManager;
    EntityQueryBuilder queryBuilder = new EntityQueryBuilder(Allocator.Temp)
        .WithAll<T>()
        .WithOptions(EntityQueryOptions.IncludeSystems);
    EntityQuery entityQuery = entityManager.CreateEntityQuery(queryBuilder);
    NativeArray<Entity> result = entityQuery.ToEntityArray(Allocator.Temp);
    queryBuilder.Dispose();
    entityQuery.Dispose();
    return result;
}