Scopie

Minimal mapping of incoming parameters to named scopes in your resources through OO design

Scopie allows you to map incoming controller parameters to named scopes in your resources.

Scopie is the yet another implementation of has_scope. The key differences is dedicated class where the scopes are defined. Also, it doesn't depend from ActiveSupport or ActionPack. Please have, a look at scopie_rails if you are using Ruby on Rails framework. To override default mapping behavior you don't need to pass a block - just define a method with the same name as scope. You can DRY your custom scopes mapping logic by using helper methods defined in scopie class and use the same scopie class in multiple controllers.

Imagine the following model called graduations:

class Graduation < ActiveRecord::Base
  scope :featured, -> { where(:featured => true) }
  scope :by_degree, -> degree { where(:degree => degree) }
  scope :by_period, -> started_at, ended_at { where("started_at = ? AND ended_at = ?", started_at, ended_at) }
end

You can use those named scopes as filters by declaring them on your scopie:

class Scopies::GraduationsScopie < Scopie::Base
  has_scope :featured, type: :boolean
  has_scope :by_degree, :by_period
  has_scope :page, default: 1
  has_scope :per, default: 30

  def by_period(scope, value, _hash)
    scope.by_period(value[:started_at], value[:ended_at])
  end
end

Now, if you want to apply them to an specific resource, you just need to call apply_scopes:

class GraduationsController < ApplicationController
  def index
    @graduations = Scopie.apply_scopes(Graduation, method: :index, scopie: Scopies::GraduationsScopie.new).all
  end
end

Then for each request:

/graduations
#=> acts like a normal request

/graduations?featured=true
#=> calls the named scope and bring featured graduations

/graduations?by_period[started_at]=20100701&by_period[ended_at]=20101013
#=> brings graduations in the given period

/graduations?featured=true&by_degree=phd
#=> brings featured graduations with phd degree

Installation

Add scopie to your Gemfile or install it from Rubygems.

gem 'scopie'

Options

Scopie supports several options:

• :type - Checks the type of the parameter sent.

• :only - In which actions the scope is applied.

• :except - In which actions the scope is not applied.

• :as - The key in the params hash expected to find the scope. Defaults to the scope name.

• :in - The key in the params hash expected to contain a hash holding scope name as a value.

• :default - Default value for the scope. Whenever supplied the scope is always called.

Thanks

Scopie was inspired by has_scope and pundit.

Thanks to both.