def create_multi(cls, values):
"""Creates multiple unique values at once.
:param values:
A sequence of values to be unique. See :meth:`create`.
:returns:
A tuple (bool, list_of_keys). If all values were created, bool is
True and list_of_keys is empty. If one or more values weren't
created, bool is False and the list contains all the values that
already existed in datastore during the creation attempt.
"""
# Maybe do a preliminary check, before going for transactions?
# entities = model.get_multi(keys)
# existing = [entity.key.id() for entity in entities if entity]
# if existing:
# return False, existing
# Create all records transactionally.
keys = [model.Key(cls, value) for value in values]
entities = [cls(key=key) for key in keys]
func = lambda e: e.put() if not e.key.get() else None
created = [model.transaction(lambda: func(e)) for e in entities]
if created != keys:
# A poor man's "rollback": delete all recently created records.
model.delete_multi(k for k in created if k)
return False, [k.id() for k in keys if k not in created]
return True, []
def create_multi(cls, values):
"""Creates multiple unique values at once.
:param values:
A sequence of values to be unique. See :meth:`create`.
:returns:
A tuple (bool, list_of_keys). If all values were created, bool is
True and list_of_keys is empty. If one or more values weren't
created, bool is False and the list contains all the values that
already existed in datastore during the creation attempt.
"""
# Maybe do a preliminary check, before going for transactions?
# entities = model.get_multi(keys)
# existing = [entity.key.id() for entity in entities if entity]
# if existing:
# return False, existing
# Create all records transactionally.
keys = [model.Key(cls, value) for value in values]
entities = [cls(key=key) for key in keys]
func = lambda e: e.put() if not e.key.get() else None
created = [model.transaction(lambda: func(e)) for e in entities]
if created != keys:
# A poor man's "rollback": delete all recently created records.
model.delete_multi(k for k in created if k)
return False, [k.id() for k in keys if k not in created]
return True, []
def get(self, name):
NOT_SET_VALUE = u'!!!__ NOT SET __!!!'
entity = self(key=model.Key(self, name))
entity.populate(value=NOT_SET_VALUE)
txn = lambda: entity.put() if not entity.key.get() else entity.key
retval = model.transaction(txn).get()
# Fall back to environment vars
if retval.value == NOT_SET_VALUE:
fallback_value = environ.get(name)
if fallback_value is not None:
retval.value = fallback_value
retval.put()
return fallback_value
if retval.value == NOT_SET_VALUE:
logging.error(
('%s %s not found in the database. A placeholder ' +
'record has been created. Go to the Developers Console '
'for your app in App Engine, look up the Settings record '
'with name=%s and enter its value in that record\'s value '
'field.') % (self.__name__, name, name))
return retval.value
def create(cls, value):
"""Creates a new unique value.
:param value:
The value to be unique, as a string.
The value should include the scope in which the value must be
unique (ancestor, namespace, kind and/or property name).
For example, for a unique property `email` from kind `User`, the
value can be `User.email:[email protected]`. In this case `User.email`
is the scope, and `[email protected]` is the value to be unique.
:returns:
True if the unique value was created, False otherwise.
"""
entity = cls(key=model.Key(cls, value))
txn = lambda: entity.put() if not entity.key.get() else None
return model.transaction(txn) is not None
def create(cls, value):
"""Creates a new unique value.
:param value:
The value to be unique, as a string.
The value should include the scope in which the value must be
unique (ancestor, namespace, kind and/or property name).
For example, for a unique property `email` from kind `User`, the
value can be `User.email:[email protected]`. In this case `User.email`
is the scope, and `[email protected]` is the value to be unique.
:returns:
True if the unique value was created, False otherwise.
"""
entity = cls(key=model.Key(cls, value))
txn = lambda: entity.put() if not entity.key.get() else None
return model.transaction(txn) is not None
def get(cls, name):
# Unique canary value (`None` may be a valid value for this config item)
NOT_SET_VALUE = u'!!!__ NOT SET __!!!'
# Need to ensure uniqueness in a transaction
entity = cls(key=model.Key(cls, name))
entity.populate(value=NOT_SET_VALUE)
txn = lambda: entity.put() if not entity.key.get() else entity.key
retval = model.transaction(txn).get()
if retval.value == NOT_SET_VALUE:
raise Exception((
'%s %s not found in the database. A placeholder ' +
'record has been created. Go to the Developers Console for your app ' +
'in App Engine, look up the Settings record with name=%s and enter ' +
'its value in that record\'s value field. ') % (cls.__name__, name, name))
return retval.value
