Dejavu 1.2.6, a Python ORM

Robert Brewer fumanchu at amor.org
Thu Dec 16 01:09:20 CET 2004


The Dejavu Object-Relational Mapper (version 1.2.6) is now available and
in the public domain. Get it at svn://casadeamor.com/dejavu/trunk.

Dejavu is an Object-Relational Mapper for Python applications. It is
designed to provide the "Model" third of an MVC application. Dejavu
avoids making decisions in the framework which are better left to
developers, and avoids forcing developers to make decisions which are
better left to deployers. In particular, deployers are allowed to mix
and match storage mechanisms, including how and when to cache objects in
memory, making it easier for deployers to tune applications to their
particular environment.

Dejavu provides:

MODELING LAYER
1. A subclassable Unit class for persisting objects to storage.
2. A base Unit Property class for declaring persistent object
attributes.
3. ID Sequencers.
4. Associations between Unit classes.
5. Unit Engines, Rules, and Collections.
6. Aggregation and analysis tools.

APPLICATION LAYER
1. Expressions: pure Python Unit queries. This is perhaps the most
appealing feature of Dejavu. However, since it uses bytecode hacks,
Dejavu only runs on CPython.
2. Sandboxes, which serve as Identity Maps and per-connection caches.
Unit objects are "memorized" and "recalled" from a Sandbox, using
Expressions.
3. An Arena class for application-level data.

STORAGE LAYER
1. A subclassable StorageManager class and specification. Unlike many
ORMs, Dejavu does not require you to have complete control of your back
end.
2. Specific StorageManagers for:
   a. Microsoft SQL Server via ADO.
   b. Microsoft Access (Jet) via ADO.
   c. ODBC databases (not complete = broken)
   d. Shelve to dbm.
   e. Future versions of Dejavu will support PostgreSQL, MySQL, and
SQLite. Others are being considered.

Dejavu welcomes your use and feedback as an application developer.

Dejavu also welcomes framework developers. New code for additional
Storage Managers, analysis tools, will be gladly reviewed for inclusion
in future releases. Drop me an email if you feel so inclined.


Robert Brewer
MIS
Amor Ministries
fumanchu at amor.org



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