Unity MonoBehaviour to ECS component converter

GameObjectEntity.cs

using Unity.Entities;
using UnityEngine;

[DisallowMultipleComponent]
public class GameObjectEntity : MonoBehaviour
{
	Entity entity;
	EntityManager manager;

	void Awake()
	{
		manager = Unity.Entities.World.DefaultGameObjectInjectionWorld.EntityManager;
		entity = manager.CreateEntity();
		foreach (var componentData in GetComponents<IComponentData>())
		{
			manager.AddComponentObject(entity, componentData);
		}
	}

	void OnDestroy()
	{
		try
		{
			manager.DestroyEntity(entity);
		}
		catch
		{
			// Entity manager has already been deallocated.
		}
	}
}