Riak Shim

A teeny shim between your code and the riak-client gem. Reads database configuration out of config/riak.yml and derives bucket names from your class names and an appropriate prefix.

Riak is a database from the good people at Basho. Check it out: http://basho.com/products/riak-overview/

Installation

Add this line to your application's Gemfile:

gem 'riak-shim'

And then execute:

$ bundle

Or install it yourself as:

$ gem install riak-shim

Usage

Create a config/riak.yml containing the details of your Riak setup like so:

development: &default
  bucket_prefix: myapp_dev_
  host: localhost
  http_port: 8098

test:
  <<: *default
  bucket_prefix: myapp_test_

production:
  <<: *default
  bucket_prefix: myapp_production_

bucket_prefix will be prefixed to each bucket name, allowing you to point multiple applications (or multiple copies of the same application) at a single Riak install. During development, this prevents you from stepping on your own toes.

Converting a model to use Riak

In any class you wish to persist, you must include the module:

require 'riak-shim'
include Riak::Shim::Persistable

Then, write a #to_hash method which returns a hash representing your object (and consequently, what you are going to store):

def to_hash
  # Return hashified version of your class
  { 'foo' => @foo, 'bar' => @bar }
end

You'll use Class#from_hash to create an instance from the hash which was pulled from Riak:

def self.from_hash(data)
  # Return a fresh instance of your class populated by the hash provided
  your_obj = new
  your_obj.foo = data['foo']
  your_obj.bar = data['bar']
  return your_obj
end

You can now save instances of your class by calling #save and later retrieve them from Riak by calling .for_key:

an_instance.save
key = an_instance.key
retrieved_copy = YourClass.for_key(key)

Secondary indexes

Secondary indexes in Riak allow you to query based on the contents of a particular field. If you'd like to look up your data by the contents of fields, define #fields_to_index and return the names of any fields you wish to query on. When you #save an instance of YourClass, riak-shim will populate a secondary index for that field.

def fields_to_index
  # Return an Array of hash keys you would like placed into a secondary index.
  [foo]
end

The for_index method retrieves all records whose value for the given index matches:

YourClass.for_index('foo_bin', 'some foo')

...where index_name is what you defined in fields_to_index plus the suffix "_bin" .

The value is what you want to look up.

Return value is an Array of instances of your class matching the query.

Contributing

For a look at what work is needed (at least according to me), see FUTURE_WORK.md

1. Fork it
2. Create your feature branch (git checkout -b my-new-feature)
3. Commit your changes (git commit -am 'Added some feature')
4. Push to the branch (git push origin my-new-feature)
5. Create new Pull Request