add_query

Add a query to the BatchOperation, to be executed when the operation is run.

The query will return a Entry (of subclass type entry_type) representing the given entry id. The ID is of the same format as that returned by get_id.

Note that a single batch operation should not operate on a given Entry more than once, as there's no guarantee about the order in which the batch operation's operations will be performed.

callback will be called when the BatchOperation is run with run (in which case it will be called in the thread which ran the batch operation), or with run_async (in which case it will be called in an idle handler in the main thread). The operation_id passed to the callback will match the return value of add_query, and the operation_type will be QUERY . If the query was successful, the resulting entry will be passed to the callback function as entry, and error will be null. If, however, the query was unsuccessful, entry will be null and error will contain a Error detailing what went wrong.

Parameters:

this	a BatchOperation
id	the ID of the entry being queried for
entry_type	the type of the entry which will be returned
callback	a BatchOperationCallback to call when the query is finished, or null
user_data	data to pass to the callback function

Returns:

operation ID for the added query, or 0