Method HasSingleton

HasSingleton<T>()

Checks whether a singleton component of the specified type exists. Note that if querying a singleton component from a system-associated entity, the query must include either EntityQueryOptions.IncludeSystems or the SystemInstance component.

Declaration

[GenerateTestsForBurstCompatibility(GenericTypeArguments = new Type[] { typeof(BurstCompatibleComponentData) })]
public bool HasSingleton<T>()

Returns

Type	Description
bool	True, if a singleton is found to match exactly once with the specified typeEntityQuery.

Type Parameters

Name	Description
T	The IComponentData subtype of the singleton component. This component type must not implement IEnableableComponent

Remarks

This method matches only the entities that this query matches, so the query's EntityQueryOptions determine whether a singleton entity is found. Unless the query uses IncludeDisabledEntities or IncludePrefab, entities that have the Disabled component or the Prefab component are excluded, and this method returns false for a singleton on one of those entities.

Exceptions

Type	Condition
InvalidOperationException	Thrown if T implements IEnableableComponent and if safety checks are enabled.
InvalidOperationException	Thrown if the number of entities that match this query is greater than one.