Activerecord::View

Integration for ActiveRecord to facilitate easy use of views in migrations.

Add this line to your application's Gemfile:

gem 'activerecord-view'

And then execute:

$ bundle

Or install it yourself as:

$ gem install activerecord-view

To create a view in a database migration:

def change
  # You can provide a string
  create_view :admins, 'SELECT * FROM users WHERE role = "admin"'

  # Or an object that responds #to_sql
  users = User.arel_table

  create_view :authors, users.project('*').where(users[:role].eq('author'))

  # Or a block that returns one of the above if that's more convenient
  create_view :magicians do
    users.project('*').where(users[:role].eq('magician'))
  end
end

Use with change is fully supported, commands will revert and do the right thing.

Reverting a drop_view requires you to pass the body to restore somehow:

def change
  drop_view :authors, original_authors_definition_from_elsewhere

  drop_view :admins do
    original_admins_definition_from_elsewhere
  end

  # In a change method, this will raise an ActiveRecord::IrreversibleMigration!
  drop_view :magicians
end

Then, in your model

class Magician < ActiveRecord::Base
  is_view!
end

By default, views are made read-only. MySQL and Postgres support the notion of updatable views, but this currently isn't tested.

If you want to make a view updatable:

class Magician < ActiveRecord::Base
  is_view! readonly: false
end

Postgres supports materialized views, and so does this gem.

def change
  users = User.arel_table

  by_role = ->(role) { users.project('*').where(users[:role].eq('admin')) }

  # The API is basically the same
  create_materialized_view :admins do
    by_role.call 'admin'
  end

  # Except there's the option to pass `with_data: true` to prepopulate the view.
  create_materialized_view :authors, with_data: true do
    by_role.call 'author'
  end

  create_materialized_view :magicians, by_role['magician'], with_data: true

  # Materialized views support indexing
  add_index :admins, :name
  add_index :magicians, :name
  add_index :authors, :email, unique: true
end

Then, in your model:

class Author < ActiveRecord::Base
  is_materialized_view!
end

Like regular views above, materialized views can also be made updatable on MySQL and Postgres if the conditions are met, via is_materialized_view! readonly: false.

To refresh a materialized view, use ModelName.refresh_view!.

Concurrent refresh (PG 9.4) is not yet supported through the gem, but it is on the roadmap.

• Ruby 2.1+
• ActiveRecord 4.1+

After checking out the repo, run bin/setup to install dependencies. Then, run bin/console for an interactive prompt that will allow you to experiment.

To install this gem onto your local machine, run bundle exec rake install. To release a new version, update the version number in version.rb, and then run bundle exec rake release to create a git tag for the version, push git commits and tags, and push the .gem file to rubygems.org.

1. Fork it ( https://github.com/scryptmouse/activerecord-view/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 a new Pull Request