--- /dev/null
+module ActiveRecord
+ module NamedScope
+ # All subclasses of ActiveRecord::Base have two named \scopes:
+ # * <tt>all</tt> - which is similar to a <tt>find(:all)</tt> query, and
+ # * <tt>scoped</tt> - which allows for the creation of anonymous \scopes, on the fly: <tt>Shirt.scoped(:conditions => {:color => 'red'}).scoped(:include => :washing_instructions)</tt>
+ #
+ # These anonymous \scopes tend to be useful when procedurally generating complex queries, where passing
+ # intermediate values (scopes) around as first-class objects is convenient.
+ def self.included(base)
+ base.class_eval do
+ extend ClassMethods
+ named_scope :scoped, lambda { |scope| scope }
+ end
+ end
+
+ module ClassMethods
+ def scopes
+ read_inheritable_attribute(:scopes) || write_inheritable_attribute(:scopes, {})
+ end
+
+ # Adds a class method for retrieving and querying objects. A scope represents a narrowing of a database query,
+ # such as <tt>:conditions => {:color => :red}, :select => 'shirts.*', :include => :washing_instructions</tt>.
+ #
+ # class Shirt < ActiveRecord::Base
+ # named_scope :red, :conditions => {:color => 'red'}
+ # named_scope :dry_clean_only, :joins => :washing_instructions, :conditions => ['washing_instructions.dry_clean_only = ?', true]
+ # end
+ #
+ # The above calls to <tt>named_scope</tt> define class methods Shirt.red and Shirt.dry_clean_only. Shirt.red,
+ # in effect, represents the query <tt>Shirt.find(:all, :conditions => {:color => 'red'})</tt>.
+ #
+ # Unlike <tt>Shirt.find(...)</tt>, however, the object returned by Shirt.red is not an Array; it resembles the association object
+ # constructed by a <tt>has_many</tt> declaration. For instance, you can invoke <tt>Shirt.red.find(:first)</tt>, <tt>Shirt.red.count</tt>,
+ # <tt>Shirt.red.find(:all, :conditions => {:size => 'small'})</tt>. Also, just
+ # as with the association objects, named \scopes act like an Array, implementing Enumerable; <tt>Shirt.red.each(&block)</tt>,
+ # <tt>Shirt.red.first</tt>, and <tt>Shirt.red.inject(memo, &block)</tt> all behave as if Shirt.red really was an Array.
+ #
+ # These named \scopes are composable. For instance, <tt>Shirt.red.dry_clean_only</tt> will produce all shirts that are both red and dry clean only.
+ # Nested finds and calculations also work with these compositions: <tt>Shirt.red.dry_clean_only.count</tt> returns the number of garments
+ # for which these criteria obtain. Similarly with <tt>Shirt.red.dry_clean_only.average(:thread_count)</tt>.
+ #
+ # All \scopes are available as class methods on the ActiveRecord::Base descendent upon which the \scopes were defined. But they are also available to
+ # <tt>has_many</tt> associations. If,
+ #
+ # class Person < ActiveRecord::Base
+ # has_many :shirts
+ # end
+ #
+ # then <tt>elton.shirts.red.dry_clean_only</tt> will return all of Elton's red, dry clean
+ # only shirts.
+ #
+ # Named \scopes can also be procedural:
+ #
+ # class Shirt < ActiveRecord::Base
+ # named_scope :colored, lambda { |color|
+ # { :conditions => { :color => color } }
+ # }
+ # end
+ #
+ # In this example, <tt>Shirt.colored('puce')</tt> finds all puce shirts.
+ #
+ # Named \scopes can also have extensions, just as with <tt>has_many</tt> declarations:
+ #
+ # class Shirt < ActiveRecord::Base
+ # named_scope :red, :conditions => {:color => 'red'} do
+ # def dom_id
+ # 'red_shirts'
+ # end
+ # end
+ # end
+ #
+ #
+ # For testing complex named \scopes, you can examine the scoping options using the
+ # <tt>proxy_options</tt> method on the proxy itself.
+ #
+ # class Shirt < ActiveRecord::Base
+ # named_scope :colored, lambda { |color|
+ # { :conditions => { :color => color } }
+ # }
+ # end
+ #
+ # expected_options = { :conditions => { :colored => 'red' } }
+ # assert_equal expected_options, Shirt.colored('red').proxy_options
+ def named_scope(name, options = {}, &block)
+ name = name.to_sym
+ scopes[name] = lambda do |parent_scope, *args|
+ Scope.new(parent_scope, case options
+ when Hash
+ options
+ when Proc
+ options.call(*args)
+ end, &block)
+ end
+ (class << self; self end).instance_eval do
+ define_method name do |*args|
+ scopes[name].call(self, *args)
+ end
+ end
+ end
+ end
+
+ class Scope
+ attr_reader :proxy_scope, :proxy_options
+ NON_DELEGATE_METHODS = %w(nil? send object_id class extend find size count sum average maximum minimum paginate first last empty? any? respond_to?).to_set
+ [].methods.each do |m|
+ unless m =~ /^__/ || NON_DELEGATE_METHODS.include?(m.to_s)
+ delegate m, :to => :proxy_found
+ end
+ end
+
+ delegate :scopes, :with_scope, :to => :proxy_scope
+
+ def initialize(proxy_scope, options, &block)
+ [options[:extend]].flatten.each { |extension| extend extension } if options[:extend]
+ extend Module.new(&block) if block_given?
+ @proxy_scope, @proxy_options = proxy_scope, options.except(:extend)
+ end
+
+ def reload
+ load_found; self
+ end
+
+ def first(*args)
+ if args.first.kind_of?(Integer) || (@found && !args.first.kind_of?(Hash))
+ proxy_found.first(*args)
+ else
+ find(:first, *args)
+ end
+ end
+
+ def last(*args)
+ if args.first.kind_of?(Integer) || (@found && !args.first.kind_of?(Hash))
+ proxy_found.last(*args)
+ else
+ find(:last, *args)
+ end
+ end
+
+ def size
+ @found ? @found.length : count
+ end
+
+ def empty?
+ @found ? @found.empty? : count.zero?
+ end
+
+ def respond_to?(method, include_private = false)
+ super || @proxy_scope.respond_to?(method, include_private)
+ end
+
+ def any?
+ if block_given?
+ proxy_found.any? { |*block_args| yield(*block_args) }
+ else
+ !empty?
+ end
+ end
+
+ protected
+ def proxy_found
+ @found || load_found
+ end
+
+ private
+ def method_missing(method, *args, &block)
+ if scopes.include?(method)
+ scopes[method].call(self, *args)
+ else
+ with_scope :find => proxy_options, :create => proxy_options[:conditions].is_a?(Hash) ? proxy_options[:conditions] : {} do
+ method = :new if method == :build
+ proxy_scope.send(method, *args, &block)
+ end
+ end
+ end
+
+ def load_found
+ @found = find(:all)
+ end
+ end
+ end
+end
projects / depot.git / blobdiff