def _ProjectionPartialEntityGenerator(cursor):
"""Generator that creates partial entities for projection.
Generate partial datastore entities from a cursor, holding only the values
being projected. These entities might share a key.
Args:
cursor: a SQLite3.Cursor or subclass.
Yields:
Partial entities resulting from the projection.
"""
for row in cursor:
entity_original = entity_pb.EntityProto(row[1])
entity = entity_pb.EntityProto()
entity.mutable_key().MergeFrom(entity_original.key())
entity.mutable_entity_group().MergeFrom(entity_original.entity_group())
for name, value_data in zip(row[2::2], row[3::2]):
prop_to_add = entity.add_property()
prop_to_add.set_name(ToUtf8(name))
value_decoder = sortable_pb_encoder.Decoder(
array.array('B', str(value_data)))
prop_to_add.mutable_value().Merge(value_decoder)
prop_to_add.set_multiple(False)
datastore_stub_util.PrepareSpecialPropertiesForLoad(entity)
yield entity
def Query(self, query, filters, orders):
"""Perform a query on this pseudo-kind.
Args:
query: the original datastore_pb.Query
filters: the filters from query
orders: the orders from query
Returns:
A query cursor to iterate over the query results, or None if the query
is invalid.
"""
property_range = datastore_stub_util.ParsePropertyQuery(
query, filters, orders)
keys_only = query.keys_only()
conn = self._stub._GetConnection()
cursor = None
try:
prefix = self._stub._GetTablePrefix(query)
filters = []
def AddExtremeFilter(extreme, inclusive, is_end):
"""Add filter for kind start/end."""
if not is_end:
op = datastore_pb.Query_Filter.GREATER_THAN_OR_EQUAL
else:
op = datastore_pb.Query_Filter.LESS_THAN_OR_EQUAL
filters.append(('kind', op, extreme[0]))
property_range.MapExtremes(AddExtremeFilter)
for name in datastore_stub_util.GetInvisibleSpecialPropertyNames():
filters.append(('name', '!=', name))
params = []
sql_filters = self._stub._CreateFilterString(filters, params)
if not keys_only:
sql_stmt = (
'SELECT kind, name, value FROM "%s!EntitiesByProperty" %s '
'GROUP BY kind, name, substr(value, 1, 1) '
'ORDER BY kind, name' % (prefix, sql_filters))
else:
sql_stmt = (
'SELECT kind, name FROM "%s!EntitiesByProperty" %s '
'GROUP BY kind, name ORDER BY kind, name' %
(prefix, sql_filters))
c = conn.execute(sql_stmt, params)
properties = []
kind = None
name = None
property_pb = None
for row in c.fetchall():
if not (row[0] == kind and row[1] == name):
if not property_range.Contains((row[0], row[1])):
continue
kind, name = row[:2]
if property_pb:
properties.append(property_pb)
property_pb = MakeEntityForQuery(query,
KindPseudoKind.name,
ToUtf8(kind), self.name,
ToUtf8(name))
if not keys_only:
value_data = row[2]
value_decoder = sortable_pb_encoder.Decoder(
array.array('B', str(value_data)))
raw_value_pb = entity_pb.PropertyValue()
raw_value_pb.Merge(value_decoder)
tag = datastore_types.GetPropertyValueTag(raw_value_pb)
tag_name = datastore_stub_util._PROPERTY_TYPE_NAMES[tag]
representation_pb = property_pb.add_property()
representation_pb.set_name('property_representation')
representation_pb.set_multiple(True)
representation_pb.mutable_value().set_stringvalue(tag_name)
if property_pb:
properties.append(property_pb)
cursor = datastore_stub_util._ExecuteQuery(properties, query, [],
[], [])
finally:
self._stub._ReleaseConnection(conn)
return cursor
