Method SetSingleton

SetSingleton<T>(T)

Sets the value of a singleton component. Note that if querying a singleton component from a system-associated entity, the query must include either EntityQueryOptions.IncludeSystems or the SystemInstance component.

Declaration

public void SetSingleton<T>(T value) where T : unmanaged, IComponentData

Parameters

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

Type Parameters

Name	Description
T	The component type.

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.