def _entity_related_entities(self, extent_name, oid):
"""Return a dictionary of related entity sets for an entity in
`extent` with given OID."""
entity_classes = self._entity_classes
entity_map, extent_map = self._entity_extent_map(extent_name, oid)
field_id_name = extent_map['field_id_name']
entity_field_ids = extent_map['entity_field_ids']
fields = entity_map['fields']
related_entities = {}
for field_id in entity_field_ids:
# During database evolution, it may turn out that fields
# get removed. For time efficiency reasons, Schevo does
# not iterate through all entities to remove existing
# data. Therefore, when getting entity fields from the
# database here, ignore fields that exist in the entity
# but no longer exist in the extent.
field_name = field_id_name.get(field_id, None)
if field_name:
value = fields.get(field_id, None)
if isinstance(value, tuple):
value = Placeholder.new(*value)
related_entities[field_name] = frozenset([value])
else:
related_entities[field_name] = frozenset()
return related_entities
def _entity_field(self, extent_name, oid, name):
"""Return the value of a field in an entity in named extent
with given OID."""
entity_map, extent_map = self._entity_extent_map(extent_name, oid)
field_name_id = extent_map['field_name_id']
entity_field_ids = extent_map['entity_field_ids']
field_id = field_name_id[name]
value = entity_map['fields'][field_id]
if field_id in entity_field_ids and isinstance(value, tuple):
value = Placeholder.new(*value)
return value
