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adewes / blitzdb

Blitz is a document-oriented database for Python that is backend-agnostic. It comes with a flat-file database for JSON documents and provides MongoDB-like querying capabilities.
http://blitzdb.readthedocs.org
MIT License
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Blitz-DB

Build Status PyPI Code Issues Python 3

BlitzDB, or just Blitz is a document-based, object-oriented, transactional database written purely in Python. Among other things, it provides a powerful querying language, deep indexing of documents, compressed data storage and automatic referencing of embedded documents. It is reasonably fast, can be easily embedded in any Python application and does not have any external dependencies (except when using a third-party backend). In addition, you can use it as a frontend to other database engines such as MongoDB in case you should need more power.

Go To Main Documentation

Key Features

Use Cases

Blitz can be used as a standalone document store for client application. Originally blitz was designed for use with the checkmate Python code analysis toolkit, where it stores statistical data. Since blitz stores all documents as single JSON files, it is possible to put the whole database under version-control.

Installation

The easiest way to install Blitz is through pip or easy_install

pip install blitzdb
#or...
easy_install blitzdb

For more detailed installation instructions, have a look at the documentation.

Detailed Documentation

The detailed documentation for this project is hosted on ReadTheDocs, feel free to take a look!

Changelog

Contributors (in alphabetical order)

Thanks for all your contributions, without you BlitzDB wouldn't be what it is today :)

Third-Party Contributions

Examples

To get an idea of what you can do with Blitz, here are some examples.

Creating objects

from blitzdb import Document

class Movie(Document):
    pass

class Actor(Document):
    pass

the_godfather = Movie({'name': 'The Godfather','year':1972,'pk':1L})

marlon_brando = Actor({'name':'Marlon Brando','pk':1L})
al_pacino = Actor({'name' : 'Al Pacino','pk':1L})

Storing objects in the database:

from blitzdb import FileBackend

backend = FileBackend("/path/to/my/db")

the_godfather.save(backend)
marlon_brando.save(backend)
al_pacino.save(backend)

Retrieving objects from the database:

the_godfather = backend.get(Movie,{'pk':1L})
#or...
the_godfather = backend.get(Movie,{'name' : 'The Godfather'})

Filtering objects

movies_from_1972 = backend.filter(Movie,{'year' : 1972})

Working with transactions

backend.begin()
the_godfather.director = 'Roland Emmerich' #oops...
the_godfather.save()
backend.rollback() #undo the changes...

Creating nested object references

the_godfather.cast = {'Don Vito Corleone' : marlon_brando, 'Michael Corleone' : al_pacino}

#Documents stored within other objects will be automatically converted to database references.

marlon_brando.performances = [the_godfather]
al_pacino.performances = [the_godfather]

marlon_brando.save(backend)
al_pacino.save(backend)
the_godfather.save(backend)
#Will store references to the movies within the documents in the DB

Creation of database indexes and advanced querying

backend.create_index(Actor,'performances')
#Will create an index on the 'performances' field, for fast querying

godfather_cast = backend.filter(Actor,{'movies' : the_godfather})
#Will return 'Al Pacino' and 'Marlon Brando'

Arbitrary filter expressions

star_wars_iv = Movie({'name' : 'Star Wars - Episode IV: A New Hope','year': 1977})
star_wars_iv.save()

movies_from_the_seventies = backend.filter(Movie,{'year': lambda year : year >= 1970 and year < 1980})
#Will return Star Wars & The Godfather (man, what a decade!)