offtheshelf

offtheshelf is a pure-Python module providing a very simple and minimalist embedded NoSQL database. It uses the shelve module as backend for persistent storage and relies on file-locking as a simple mutual exclusion mechanism.

It has no dependencies and runs on both Python 2.x and 3.x.

Installation

Download the package from GitHub and run the install script:

# python setup.py install

Basic usage

offtheshelf defines two classes: Database and Collection.

A Database object is basically a container for one or more Collections. A Collection contains a list of documents (i.e. dictionaries), holding the actual data, and provides methods for inserting, updating, searching and removing items from documents.

Database instances support closures and can be either returned by a call to the openDB() function or instantiated directly; e.g.:

>>> with offtheshelf.openDB("/tmp/music") as db:
...     coll = db.get_collection("CDCollection")
...     coll.insert({"Author": "W. A. Mozart",
...                  "Title":  "Symphony K.551 - Jupiter"})
...     coll.insert({"Author": "L. Van Beethoven",
...                  "Title":  "Symphony n.5 op.67"})

Collections can be queried, updated, counted and deleted; e.g.:

...     coll.count({"Author": "L. Van Beethoven"})
1
...     coll.find({"Author": "W. A. Mozart"})
[{'Author': 'W. A. Mozart', 'Title': 'Symphony K.551 - Jupiter'}]
...     # Don't worry Ludwig, it's only an example! :-(
...     coll.delete({"Author": "L. Van Beethoven"})
...

The Database is automatically saved and closed upon exit from the closure, but can be also explicitely saved and closed; e.g.:

>>> db = Database("/tmp/music")
>>> coll = db.get_collection("CDCollection")
>>> coll.update({"Genre": "Classical"})
>>> db.save()
>>> db.close()

Documentation

More examples and a detailed description of the module and its classes are available at http://www.kernel-panic.it/programming/offtheshelf/.

Tests

To run the test suite, just run python setup.py test.

Credits

Copyright (c) 2012 Daniele Mazzocchio (danix@kernel-panic.it).

Licensed under BSD license (see LICENSE.md file).