Method HasComponent

HasComponent<T>(Entity)

Checks whether an entity has a specific type of component.

Declaration

protected bool HasComponent<T>(Entity entity)
    where T : struct, IComponentData

Parameters

Type	Name	Description
Entity	entity	The Entity object.

Returns

Type	Description
Boolean	True, if the specified entity has the component.

Type Parameters

Name	Description
T	The data type of the component.

Remarks

Always returns false for an entity that has been destroyed.

Use this method to check if another entity has a given type of component using its Entity object. For example, if you have a component that contains an Entity field, you can check whether the referenced entity has a specific type of component using this method. (Entities in the set always have required components, so you don’t need to check for them.)

When iterating over a set of entities via Entities.ForEach, avoid using this method with the current entity in the set. It is generally faster to change your entity query methods to avoid optional components; this may require a different Entities.ForEach construction to handle each combination of optional and non-optional components.

When you call this method on the main thread, it invokes HasComponent<T>(Entity). (An Entities.ForEach function invoked with Run() executes on the main thread.) When you call this method inside a job scheduled using Entities.ForEach, this method gets replaced with component access methods through ComponentDataFromEntity<T>.

In both cases, this lookup method results in a slower, indirect memory access. When possible, organize your data to minimize the need for indirect lookups.