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Rom - the Redis object mapper for Python

Copyright 2013 Josiah Carlson

Released under the LGPL license.

Rom is a package whose purpose is to offer active-record style data modeling within Redis from Python, similar to the semantics of Django ORM, SQLAlchemy + Elixir, Google's Appengine datastore, and others.

I was building a personal project, wanted to use Redis to store some of my data, but didn't want to hack it poorly. I looked at the existing Redis object mappers available in Python, but didn't like the features and functionality offered.

Data types:

• Strings, ints, floats, decimals
• Json columns (for nested structures)
• OneToMany and ManyToOne columns (for model references)

Indexes:

• Numeric range fetches, searches, and ordering
• Full-word text search (find me entries with col X having words A and B)

Other features:

• Per-thread entity cache (to minimize round-trips, easy saving of all entities)

1. Make sure you have Python 2.6 or 2.7 installed

2. Make sure that you have Andy McCurdy's Redis library installed: https://github.com/andymccurdy/redis-py/ or https://pypi.python.org/pypi/redis

3. (optional) Make sure that you have the hiredis library installed for Python

4. Make sure that you have a Redis server installed and available remotely

5. Update the Redis connection settings for rom via rom.util.set_connection_settings() (other connection update options, including per-model connections, can be read about in the rom.util documentation):

   import redis
   from rom import util
   
   util.set_connection_settings(host='myhost', db=7)
   

6. Create a model:

   class User(Model):
       email_address = String(required=True, unique=True)
       salt = String()
       hash = String()
       created_at = Float(default=time.time)
   

7. Create an instance of the model and save it:

   PASSES = 32768
   def gen_hash(password, salt=None):
       salt = salt or os.urandom(16)
       comp = salt + password
       out = sha256(comp).digest()
       for i in xrange(PASSES-1):
           out = sha256(out + comp).digest()
       return salt, out
   
   user = User(email_address='[email protected]')
   user.salt, user.hash = gen_hash(password)
   user.save()
   # session.commit() or session.flush() works too
   

8. Load and use the object later:

   user = User.get_by(email_address='[email protected]')