def QueryFollowerIds(cls,
client,
viewpoint_id,
callback,
excl_start_key=None,
limit=None):
"""Query followers belonging to the viewpoint (up to 'limit' total) for
the specified 'viewpoint_id'. The query is for followers starting with
(but excluding) 'excl_start_key'. The callback is invoked with an array
of follower user ids and the last queried key.
"""
def _OnQueryFollowerKeys(follower_keys):
follower_ids = [key.hash_key for key in follower_keys]
last_key = follower_ids[-1] if len(follower_ids) > 0 else None
callback((follower_ids, last_key))
# Query the viewpoint_id secondary index with excl_start_key & limit.
query_expr = ('follower.viewpoint_id={id}', {'id': viewpoint_id})
start_index_key = db_client.DBKey(
excl_start_key,
viewpoint_id) if excl_start_key is not None else None
Follower.IndexQueryKeys(client,
query_expr,
callback=_OnQueryFollowerKeys,
start_index_key=start_index_key,
limit=limit)
