+ def not_null_constraints(self):
+ '''
+ Returns a list of properties that must be not NULL. Derived classes
+ should override this method if needed.
+ '''
+ return []
+
+ validation_message = \
+ "Validation failed because property '%s' must not be empty in object\n%s"
+
+ def validate(self):
+ '''
+ This function validates the not NULL constraints as returned by
+ not_null_constraints(). It raises the DBUpdateError exception if
+ validation fails.
+ '''
+ for property in self.not_null_constraints():
+ # TODO: It is a bit awkward that the mapper configuration allow
+ # directly setting the numeric _id columns. We should get rid of it
+ # in the long run.
+ if hasattr(self, property + '_id') and \
+ getattr(self, property + '_id') is not None:
+ continue
+ if not hasattr(self, property) or getattr(self, property) is None:
+ raise DBUpdateError(self.validation_message % \
+ (property, str(self)))
+
+ @classmethod
+ @session_wrapper
+ def get(cls, primary_key, session = None):
+ '''
+ This is a support function that allows getting an object by its primary
+ key.
+
+ Architecture.get(3[, session])
+
+ instead of the more verbose
+
+ session.query(Architecture).get(3)
+ '''
+ return session.query(cls).get(primary_key)
+
+ def session(self, replace = False):
+ '''
+ Returns the current session that is associated with the object. May
+ return None is object is in detached state.
+ '''
+
+ return object_session(self)
+
+ def clone(self, session = None):
+ '''
+ Clones the current object in a new session and returns the new clone. A
+ fresh session is created if the optional session parameter is not
+ provided. The function will fail if a session is provided and has
+ unflushed changes.
+
+ RATIONALE: SQLAlchemy's session is not thread safe. This method clones
+ an existing object to allow several threads to work with their own
+ instances of an ORMObject.
+
+ WARNING: Only persistent (committed) objects can be cloned. Changes
+ made to the original object that are not committed yet will get lost.
+ The session of the new object will always be rolled back to avoid
+ ressource leaks.
+ '''
+
+ if self.session() is None:
+ raise RuntimeError( \
+ 'Method clone() failed for detached object:\n%s' % self)
+ self.session().flush()
+ mapper = object_mapper(self)
+ primary_key = mapper.primary_key_from_instance(self)
+ object_class = self.__class__
+ if session is None:
+ session = DBConn().session()
+ elif len(session.new) + len(session.dirty) + len(session.deleted) > 0:
+ raise RuntimeError( \
+ 'Method clone() failed due to unflushed changes in session.')
+ new_object = session.query(object_class).get(primary_key)
+ session.rollback()
+ if new_object is None:
+ raise RuntimeError( \
+ 'Method clone() failed for non-persistent object:\n%s' % self)
+ return new_object
+