Method SetSingleton

SetSingleton<T>(EntityQuery, T)

Sets the value of a singleton component.

Declaration

public static void SetSingleton<T>(this EntityQuery query, T value) where T : class

Parameters

Type	Name	Description
EntityQuery	query	The query
T	value	An instance of type T containing the values to set.

Type Parameters

Name	Description
T	The component type. This type must not implement IEnableableComponent.

Remarks

For a component to be a singleton, there can be only one instance of that component that satisfies this query.

Note: singletons are otherwise normal entities. The EntityQuery and ComponentSystemBase singleton functions add checks that you have not created two instances of a type that can be accessed by this singleton query, but other APIs do not prevent such accidental creation.

To create a singleton, create an entity with the singleton component.

For example, if you had a component defined as:

public struct Singlet : IComponentData
{
    public int Value;
}

You could create a singleton as follows:

Entity singletonEntity = entityManager.CreateEntity(typeof(Singlet));
entityManager.SetComponentData(singletonEntity, new Singlet { Value = 1 });

To update the singleton component after creation, you can use an EntityQuery object that selects the singleton entity and call this SetSingleton() function:

queryForSingleton.SetSingleton<Singlet>(new Singlet {Value = 1});

You can set and get the singleton value from a system: see SetSingleton<T>(T) and GetSingleton<T>().

Exceptions

Type	Condition
InvalidOperationException	Thrown if more than one instance of this component type exists in the world or the component type appears in more than one archetype.

See Also

GetSingleton<T>(EntityQuery)

GetSingletonEntity()