2.1 KiB
Filtering responsibilities between controllers and drivers
Keystone supports the specification of filtering on list queries as
part of the v3 identity API. By default these queries are satisfied in
the controller class when a controller calls the
wrap_collection method at the end of a
list_{entity} method. However, to enable optimum
performance, any driver can implement some or all of the specified
filters (for example, by adding filtering to the generated SQL
statements to generate the list).
The communication of the filter details between the controller level and its drivers is handled by the passing of a reference to a Hints object, which is a list of dicts describing the filters. A driver that satisfies a filter must delete the filter from the Hints object so that when it is returned to the controller level, it knows to only execute any unsatisfied filters.
The contract for a driver for list_{entity} methods is
therefore:
- It MUST return a list of entities of the specified type
- It MAY either just return all such entities, or alternatively reduce the list by filtering for one or more of the specified filters in the passed Hints reference, and removing any such satisfied filters. An exception to this is that for identity drivers that support domains, then they should at least support filtering by domain_id.