Queryable

Queryable is a mixin that allows you to easily define query objects with chainable scopes.

Usage

class CustomerQuery
  include Queryable

  scope(:recent) { desc(:logged_in_at) }

  scope :active, ->{ where(status: 'active') }

  scope :favourite_brand do |product, brand|
    where("favourites.#{product}": brand)
  end

  def current
    recent.active
  end

  def miller_fans
    favourite_brand(:beer, :Miller)
  end

  def search_in_current(field_values)
    define_query do |customers|
      field_values.inject(customers) { |customers, (field, value)|
        customers.where(field => /#{value}/i)
      }
    end.current
  end
end


CustomerQuery.new(shop.customers).miller_fans.search_in_current(last_name: 'M')

Scopes

Scopes serve to encapsulate reusable business rules, a method is defined with the selected name and block (or proc)

Define Query

While scopes are great because of their terseness, they can be limiting because the block executes in the context of the internal query, so methods, constants, and variables of the Queryable are not accessible.

For those cases, you can use define_query, which is a convenience setter for the internal query, that also takes care of returning self at the end of the call to make the methods chainable.

Advantages

• Query objects are easy to understand.
• You can inherit, mixin, and chain queries in a very natural way.
• Increased testability, pretty close to being ORM/ODM agnostic.

Testing

You can check the specs of the project to check how to test query objects without even having to require the ORM/ODM, or you can test by requiring your ORM/ODM and executing queries as usual.

RDocs

You can view the Queryable documentation in RDoc format here:

http://rubydoc.info/github/ElMassimo/queryable/master/frames

License

Copyright (c) 2014 M