require 'active_support/core_ext/array' require 'active_support/core_ext/hash/except' require 'active_support/core_ext/kernel/singleton_class' require 'active_support/core_ext/object/blank' require 'active_support/core_ext/class/attribute' module ActiveRecord # = Active Record Named \Scopes module NamedScope extend ActiveSupport::Concern included do class_attribute :scopes self.scopes = {} end module ClassMethods # Returns an anonymous \scope. # # posts = Post.scoped # posts.size # Fires "select count(*) from posts" and returns the count # posts.each {|p| puts p.name } # Fires "select * from posts" and loads post objects # # fruits = Fruit.scoped # fruits = fruits.where(:colour => 'red') if options[:red_only] # fruits = fruits.limit(10) if limited? # # Anonymous \scopes tend to be useful when procedurally generating complex # queries, where passing intermediate values (\scopes) around as first-class # objects is convenient. # # You can define a \scope that applies to all finders using # ActiveRecord::Base.default_scope. def scoped(options = nil) if options scoped.apply_finder_options(options) else current_scoped_methods ? relation.merge(current_scoped_methods) : relation.clone end end # Adds a class method for retrieving and querying objects. A \scope represents a narrowing of a database query, # such as where(:color => :red).select('shirts.*').includes(:washing_instructions). # # class Shirt < ActiveRecord::Base # scope :red, where(:color => 'red') # scope :dry_clean_only, joins(:washing_instructions).where('washing_instructions.dry_clean_only = ?', true) # end # # The above calls to scope define class methods Shirt.red and Shirt.dry_clean_only. Shirt.red, # in effect, represents the query Shirt.where(:color => 'red'). # # Unlike Shirt.find(...), however, the object returned by Shirt.red is not an Array; it # resembles the association object constructed by a has_many declaration. For instance, # you can invoke Shirt.red.first, Shirt.red.count, Shirt.red.where(:size => 'small'). # Also, just as with the association objects, named \scopes act like an Array, implementing Enumerable; # Shirt.red.each(&block), Shirt.red.first, and Shirt.red.inject(memo, &block) # all behave as if Shirt.red really was an Array. # # These named \scopes are composable. For instance, Shirt.red.dry_clean_only will produce # all shirts that are both red and dry clean only. # Nested finds and calculations also work with these compositions: Shirt.red.dry_clean_only.count # returns the number of garments for which these criteria obtain. Similarly with # Shirt.red.dry_clean_only.average(:thread_count). # # All \scopes are available as class methods on the ActiveRecord::Base descendant upon which # the \scopes were defined. But they are also available to has_many associations. If, # # class Person < ActiveRecord::Base # has_many :shirts # end # # then elton.shirts.red.dry_clean_only will return all of Elton's red, dry clean # only shirts. # # Named \scopes can also be procedural: # # class Shirt < ActiveRecord::Base # scope :colored, lambda {|color| where(:color => color) } # end # # In this example, Shirt.colored('puce') finds all puce shirts. # # Named \scopes can also have extensions, just as with has_many declarations: # # class Shirt < ActiveRecord::Base # scope :red, where(:color => 'red') do # def dom_id # 'red_shirts' # end # end # end # # Scopes can also be used while creating/building a record. # # class Article < ActiveRecord::Base # scope :published, where(:published => true) # end # # Article.published.new.published # => true # Article.published.create.published # => true def scope(name, scope_options = {}) name = name.to_sym valid_scope_name?(name) extension = Module.new(&Proc.new) if block_given? scopes[name] = lambda do |*args| options = scope_options.respond_to?(:call) ? scope_options.call(*args) : scope_options relation = if options.is_a?(Hash) scoped.apply_finder_options(options) elsif options scoped.merge(options) else scoped end extension ? relation.extending(extension) : relation end singleton_class.send(:redefine_method, name, &scopes[name]) end protected def valid_scope_name?(name) if !scopes[name] && respond_to?(name, true) logger.warn "Creating scope :#{name}. " \ "Overwriting existing method #{self.name}.#{name}." end end end end end