def get_distinct_values(self, restype='', attr_list=None, res_filter=None):
"""Returns a list of distinct values for given resource type and list of attribute names.
Only supports simple types for the attribute values.
Returns a sorted list of values or tuples of values.
"""
if not restype or type(restype) != str:
raise BadRequest("Illegal value for argument restype")
if not hasattr(interface.objects, restype):
raise BadRequest("Given restype is not a resource type")
if not attr_list or not type(attr_list) in (list, tuple):
raise BadRequest("Illegal value for argument attr_list")
type_cls = getattr(interface.objects, restype)
try:
if not all(type_cls._schema[an]["type"] in {"str", "int", "float"} for an in attr_list):
raise BadRequest("Attribute in attr_list if invalid type")
except KeyError:
raise BadRequest("Attribute in attr_list unknown")
if res_filter and type(res_filter) not in (list, tuple):
raise BadRequest("Illegal value for argument res_filter")
# NOTE: This can alternatively be implemented as a SELECT DISTINCT query, but this is not
# supported by the underlying datastore interface.
rq = ResourceQuery()
if res_filter:
rq.set_filter(rq.eq(rq.ATT_TYPE, restype), res_filter)
else:
rq.set_filter(rq.eq(rq.ATT_TYPE, restype))
res_list = self.clients.resource_registry.find_resources_ext(query=rq.get_query(), id_only=False)
log.debug("Found %s resources of type %s", len(res_list), restype)
att_values = sorted({tuple(getattr(res, an) for an in attr_list) for res in res_list})
log.debug("Found %s distinct vales for attribute(s): %s", len(att_values), attr_list)
return att_values
