Cassandra models

Goal

A slim interaction layer with a cassandra database

Use

you will need to initialize the connection with the cassandra nodes during initialization of you application

  # get the cassandra connections
  db = CassandraCQL::Database.new("localhost", {:keyspace => "something"})

  # init models
  ObjectModel.init db

Your models in rails can have these kinds of additions:

  class ObjectModel < Cassandra::Models::Base

    # define the object's Cassandra column family
    cfname :object_models

    # a plain field
    field :uuid

    # a field that can be searched
    indexed_field :index

    # fields with the respective types.
    field :interesting, :type => :boolean
    field :bag, :type => :compound
    field :created_at, :type => :date

    # a field that is required and will throw Cassandra::Models::ValueNotFound if the value is not returned
    field :owner_id, :required => true
  end

Types:

• boolean
• compound (a compound is a string in the shape of JSON data, compound will turn that data into a Ruby Hash)
• data
• uuid (this type is detected automatically)
• timeuuid
• string (this is the default type)

Find methods:

• Class.find_by_id (Do a KEY find for one row)
• Class.find_by_index (Do a search for rows that match the index value. Note: This is for indexed_fields defined columns only)

Column methods:

• object.column (Get the column data)
• object.column= 'something' (set the column data. Note that the data is NOT stored to cassandra)

Validation methods:

• object.validate_field_column (validate the field for presence. Note: This is only for columns that had :required set to true)

Dependencies

Gems:

• cassandra-cql
• json

Ruby: Currently the gem is tested and works on RubyEE 1.8

NOTE: Object is currently ducktyped to include define_singleton_method that was only added in MRI 1.9.1. This means that if you are running a Ruby interpreter that has this method the implementation of it is overwritten by the local method.