SQLAlchemy 0.5 Documentation

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Version: 0.5.0rc3 Last Updated: 11/07/08 13:55:35

module sqlalchemy.ext.serializer

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.

Module Functions

def Deserializer(file, metadata=None, scoped_session=None, engine=None)
def Serializer(*args, **kw)
def dumps(obj)
def loads(data, metadata=None, scoped_session=None, engine=None)
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