Riak's "Links and Link Walking" for Python.

link_walking.py

#!/usr/bin/env python
# -*- coding: utf-8 -*-

from riak import RiakClient
from riak.mapreduce import RiakLink

# see http://wiki.basho.com/Links-and-Link-Walking.html

HOST = 'example.jp'

def print_links(links):
    for link in links:
        print('key: {0}, tag: {1}'.format(link.get_key(), link.get_tag()))

def main():
    client = RiakClient(host=HOST)
    bucket = client.bucket('people')

    
    # Working with Links
    tim = bucket.new('timoreilly', data='I am an excellent public speaker.')
    tim.add_link(RiakLink('people', 'dhh', tag='friend')).store()
    
    links = bucket.get('timoreilly').get_links()
    print_links(links)
    # key: dhh, tag: dhh

    bucket.new('dhh', data='I drive a Zonda.').store()
    
    
    # Link Walking
    links = bucket.get('timoreilly').link('people', 'friend', 1).run()
    print_links(links)
    # key: dhh, tag: dhh
    
    links = bucket.get('timoreilly').link('_', 'friend', 1).run()
    print_links(links)
    # key: dhh, tag: dhh
    
    davethomas = bucket.new('davethomas', data='I publish books')
    davethomas.add_link(RiakLink('people', 'timoreilly', tag='friend')).store()

    links = bucket.get('davethomas').link('_', 'friend', False).\
                                     link('_', 'friend', False).run()
    # it is required to use True/False in method chain. not 1/0.
    print_links(links)
    # key: dhh, tag: dhh

    links = bucket.get('davethomas').link('_', 'friend', True).\
                                     link('_', 'friend', False).run()
    print_links(links)
    # key: timoreilly, tag: friend

    dhh = bucket.get('dhh')
    dhh.add_link(RiakLink('people', 'davethomas', tag='friend')).store()

    links = bucket.get('davethomas').link('_', 'friend', False).\
                                     link('_', 'friend', False).\
                                     link('_', 'friend', False).run()
    print_links(links)
    # key: davethomas, tag: friend


if __name__ == '__main__':
    main()