Slaver

Welcome to slaver!

It's a simple gem for rails application within multi-database environment. It allows you to change your current connection to other database configuration. Some ideas was inspired by octopus.

WARNING

It was tested only on rails 3 and ruby 1.9.3. Other configurations may work or may not:)

Installation

Add this line to your application's Gemfile:

gem 'slaver'

And then execute:

$ bundle

Or install it yourself as:

$ gem install slaver

Usage

Config

You must have other connection on your database.yml file. For example:

production:
  adapter: pg
  host: master
  database: master
  post: 11111

production_slave:
  adapter: sqlite3
  host: slave
  database: slave
  post: 11113

production_mysql:
  adapter: mysql
  user: me
  host: somewhere_else
  post: 11112
  database: mysql

Chain with AR

Only works with class/scope methods. Connection changed until query is perfomed. After that it'll swiched back to default connection.

  SomeModel.on(:production_mysql).where(name: 'me').first


  # or, if you name starting with you Rails.env it can be skipped
  SomeModel.on(:mysql).where(name: 'me').to_a

Execute block on other connection

Connection will be switched for any query in block.

  # simple usage
  SomeModel.within(:slave) do
    SomeModel.where(name: 'me')
  end

  # It also can be combined with "on" method
  SomeModel.within(:mysql) do
    me = SomeModel.find_by_name('me')
    SomeModel.on(:slave).find_by_name('me').update_attributes(me.attributes)
  end

  # it can execute multi-models queries on other connection
  ActiveRecord::Base.within(:slave) do
    SomeModel.where(name: 'me').first
    OtherModel.where(name: 'me').first
  end

Execute whole method on any class on other connection

class Some
  extend Slavable

  def some_method
    Foo.create
    f = Foo.where(...).first
    other = SomeModel.where(...).first
    f.update_attributes(...)
    other.update_attributes(...)
    ...
  end

  def self.class_method
    b = Bar.create
    b.update_attributes(...)
    Foo.where(bar: b)
    ....
  end

  switch :some_method, to: :other

  # it also can be called on multiple methods and works with class_methods

  switch :some_method, ..., to: :other

  # for switching class method just use singleton class pattern:
  class << self
    extend Slavable

    switch :class_method, ..., to: :other
  end
  ....
end

# it''ll be executed with :other connection
Some.class_method
Some.new.some_method

ACHTUNG!!!!

If you connection does not exists, behavior may change dependent of you current Rails environment:

• Rails.env == production: It'll raise ArgumentError
• otherwise: It'll try to switch to default connection - Rails.env

Missing features

1. 'on' with assosiations
2. Transaction safety
3. on method on instance

Development

To run test on local machine use make command. For more info please reffer to Makefile.

Contributing

1. Fork it ( https://github.com/abak-press/slaver/fork )
2. Create your feature branch (git checkout -b my-new-feature)
3. Commit your changes (git commit -am 'Add some feature')
4. Push to the branch (git push origin my-new-feature)
5. Create new Pull Request

License

The gem is available as open source under the terms of the MIT License.