serializer

author:Mike Bayer

Serializer/Deserializer objects for usage with SQLAlchemy structures.

Any SQLAlchemy structure, including Tables, Columns, expressions, mappers, Query objects etc. can be serialized in a minimally-sized format, and deserialized when given a Metadata and optional ScopedSession object to use as context on the way out.

Usage is nearly the same as that of the standard Python pickle module:

from sqlalchemy.ext.serializer import loads, dumps
metadata = MetaData(bind=some_engine)
Session = scoped_session(sessionmaker())

# ... define mappers

query = Session.query(MyClass).filter(MyClass.somedata=='foo').order_by(MyClass.sortkey)

# pickle the query
serialized = dumps(query)

# unpickle.  Pass in metadata + scoped_session
query2 = loads(serialized, metadata, Session)

print query2.all()

Similar restrictions as when using raw pickle apply; mapped classes must be themselves be pickleable, meaning they are importable from a module-level namespace.

Note that instances of user-defined classes do not require this extension in order to be pickled; these contain no references to engines, sessions or expression constructs in the typical case and can be serialized directly. This module is specifically for ORM and expression constructs.

sqlalchemy.ext.serializer.Serializer(*args, **kw)

sqlalchemy.ext.serializer.Deserializer(file, metadata=None, scoped_session=None, engine=None)

sqlalchemy.ext.serializer.dumps(obj)

sqlalchemy.ext.serializer.loads(data, metadata=None, scoped_session=None, engine=None)