SpatialEntity.Persist

bool Persist()

Ask the system to persist this entity, giving it a durable identity that survives across sessions! This is asynchronous, and safe to call right away since it waits until the entity is tracking and persistence has started up. On success, TryGetGuid succeeds and Changed flags the Persistence component. On failure, Status becomes Partial and the entity stays without a Guid. If an Unpersist is still in flight, this persists again once it lands.


RETURNS: bool	False if this can’t work at all, like an invalid entity, or one from a capability without persistence support. Check `Spatial.ComponentsFor` for `SpatialComponent.Persistence` to see which capabilities support it.

Examples

Keeping track of anchors by Guid

For apps that keep anchors in their own save data instead of by name. The Guid arrives a moment after Persist, so watch for it.

List<Guid> savedAnchors = new List<Guid>();

public void StepSavedAnchors()
{
	foreach (SpatialEntity anchor in SpatialEntity.With(SpatialComponent.Anchor))
	{
		if (anchor.HasChanged(SpatialComponent.Persistence) && anchor.TryGetGuid(out Guid guid))
			savedAnchors.Add(guid);
	}

	// Storage no longer having a Guid shows up as Failed
	foreach (SpatialEntity anchor in SpatialEntity.Removed)
	{
		if (anchor.Status == SpatialStatus.Failed && anchor.TryGetGuid(out Guid lost))
			savedAnchors.Remove(lost);
	}
}

// In a later session, each Guid loads back into its anchor
public List<SpatialEntity> RestoreAnchors()
{
	List<SpatialEntity> result = new List<SpatialEntity>();
	foreach (Guid guid in savedAnchors)
		result.Add(SpatialEntity.FindAnchor(guid));
	return result;
}

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