update AR::Scoping documentation [ci skip]

2 files changed, 77 insertions, 91 deletions

diff --git a/activerecord/lib/active_record/scoping/default.rb b/activerecord/lib/active_record/scoping/default.rb
index a2a85d4b96..6835d0e01b 100644
--- a/activerecord/lib/active_record/scoping/default.rb
+++ b/activerecord/lib/active_record/scoping/default.rb
@@ -5,17 +5,17 @@ module ActiveRecord
       extend ActiveSupport::Concern
 
       included do
-        # Stores the default scope for the class
+        # Stores the default scope for the class.
         class_attribute :default_scopes, instance_writer: false
         self.default_scopes = []
       end
 
       module ClassMethods
-        # Returns a scope for the model without the default_scope.
+        # Returns a scope for the model without the +default_scope+.
         #
         #   class Post < ActiveRecord::Base
         #     def self.default_scope
-        #       where :published => true
+        #       where published: true
         #     end
         #   end
         #
@@ -23,16 +23,16 @@ module ActiveRecord
         #   Post.unscoped.all # Fires "SELECT * FROM posts"
         #
         # This method also accepts a block. All queries inside the block will
-        # not use the default_scope:
+        # not use the +default_scope+:
         #
         #   Post.unscoped {
         #     Post.limit(10) # Fires "SELECT * FROM posts LIMIT 10"
         #   }
         #
         # It is recommended that you use the block form of unscoped because
-        # chaining unscoped with <tt>scope</tt> does not work. Assuming that
-        # <tt>published</tt> is a <tt>scope</tt>, the following two statements
-        # are equal: the <tt>default_scope</tt> is applied on both.
+        # chaining unscoped with +scope+ does not work. Assuming that
+        # +published+ is a +scope+, the following two statements
+        # are equal: the +default_scope+ is applied on both.
         #
         #   Post.unscoped.published
         #   Post.published
@@ -50,35 +50,37 @@ module ActiveRecord
         # the model.
         #
         #   class Article < ActiveRecord::Base
-        #     default_scope { where(:published => true) }
+        #     default_scope { where(published: true) }
         #   end
         #
         #   Article.all # => SELECT * FROM articles WHERE published = true
         #
-        # The <tt>default_scope</tt> is also applied while creating/building a record. It is not
-        # applied while updating a record.
+        # The +default_scope+ is also applied while creating/building a record.
+        # It is not applied while updating a record.
         #
         #   Article.new.published    # => true
         #   Article.create.published # => true
         #
-        # (You can also pass any object which responds to <tt>call</tt> to the <tt>default_scope</tt>
-        # macro, and it will be called when building the default scope.)
+        # (You can also pass any object which responds to +call+ to the
+        # +default_scope+ macro, and it will be called when building the
+        # default scope.)
         #
-        # If you use multiple <tt>default_scope</tt> declarations in your model then they will
-        # be merged together:
+        # If you use multiple +default_scope+ declarations in your model then
+        # they will be merged together:
         #
         #   class Article < ActiveRecord::Base
-        #     default_scope { where(:published => true) }
-        #     default_scope { where(:rating => 'G') }
+        #     default_scope { where(published: true) }
+        #     default_scope { where(rating: 'G') }
         #   end
         #
         #   Article.all # => SELECT * FROM articles WHERE published = true AND rating = 'G'
         #
-        # This is also the case with inheritance and module includes where the parent or module
-        # defines a <tt>default_scope</tt> and the child or including class defines a second one.
+        # This is also the case with inheritance and module includes where the
+        # parent or module defines a +default_scope+ and the child or including
+        # class defines a second one.
         #
-        # If you need to do more complex things with a default scope, you can alternatively
-        # define it as a class method:
+        # If you need to do more complex things with a default scope, you can
+        # alternatively define it as a class method:
         #
         #   class Article < ActiveRecord::Base
         #     def self.default_scope
@@ -100,7 +102,7 @@ module ActiveRecord
           self.default_scopes = default_scopes + [scope]
         end
 
-        def build_default_scope #:nodoc:
+        def build_default_scope # :nodoc:
           if !Base.is_a?(method(:default_scope).owner)
             # The user has defined their own default scope method, so call that
             evaluate_default_scope { default_scope }
@@ -117,17 +119,18 @@ module ActiveRecord
           end
         end
 
-        def ignore_default_scope? #:nodoc:
+        def ignore_default_scope? # :nodoc:
           Thread.current["#{self}_ignore_default_scope"]
         end
 
-        def ignore_default_scope=(ignore) #:nodoc:
+        def ignore_default_scope=(ignore) # :nodoc:
           Thread.current["#{self}_ignore_default_scope"] = ignore
         end
 
-        # The ignore_default_scope flag is used to prevent an infinite recursion situation where
-        # a default scope references a scope which has a default scope which references a scope...
-        def evaluate_default_scope
+        # The ignore_default_scope flag is used to prevent an infinite recursion
+        # situation where a default scope references a scope which has a default
+        # scope which references a scope...
+        def evaluate_default_scope # :nodoc:
           return if ignore_default_scope?
 
           begin
diff --git a/activerecord/lib/active_record/scoping/named.rb b/activerecord/lib/active_record/scoping/named.rb
index 75f31229b5..fb5f5b5be0 100644
--- a/activerecord/lib/active_record/scoping/named.rb
+++ b/activerecord/lib/active_record/scoping/named.rb
@@ -3,7 +3,7 @@ require 'active_support/core_ext/hash/except'
 require 'active_support/core_ext/kernel/singleton_class'
 
 module ActiveRecord
-  # = Active Record Named \Scopes
+  # = Active Record \Named \Scopes
   module Scoping
     module Named
       extend ActiveSupport::Concern
@@ -16,11 +16,11 @@ module ActiveRecord
         #   posts.each {|p| puts p.name } # Fires "select * from posts" and loads post objects
         #
         #   fruits = Fruit.all
-        #   fruits = fruits.where(:color => 'red') if options[:red_only]
+        #   fruits = fruits.where(color: 'red') if options[:red_only]
         #   fruits = fruits.limit(10) if limited?
         #
-        # You can define a \scope that applies to all finders using
-        # ActiveRecord::Base.default_scope.
+        # You can define a scope that applies to all finders using
+        # <tt>ActiveRecord::Base.default_scope</tt>.
         def all
           if current_scope
             current_scope.clone
@@ -31,7 +31,6 @@ module ActiveRecord
           end
         end
 
-        ##
         # Collects attributes from scopes that should be applied when creating
         # an AR instance for the particular class this is called on.
         def scope_attributes # :nodoc:
@@ -44,86 +43,70 @@ module ActiveRecord
           end
         end
 
-        ##
         # Are there default attributes associated with this scope?
         def scope_attributes? # :nodoc:
           current_scope || default_scopes.any?
         end
 
-        # Adds a class method for retrieving and querying objects. A \scope represents a narrowing of a database query,
-        # such as <tt>where(:color => :red).select('shirts.*').includes(:washing_instructions)</tt>.
+        # Adds a class method for retrieving and querying objects. A \scope
+        # represents a narrowing of a database query, such as
+        # <tt>where(color: :red).select('shirts.*').includes(:washing_instructions)</tt>.
         #
         #   class Shirt < ActiveRecord::Base
-        #     scope :red, where(:color => 'red')
-        #     scope :dry_clean_only, joins(:washing_instructions).where('washing_instructions.dry_clean_only = ?', true)
+        #     scope :red, -> { where(color: 'red') }
+        #     scope :dry_clean_only, -> { joins(:washing_instructions).where('washing_instructions.dry_clean_only = ?', true) }
         #   end
         #
-        # The above calls to <tt>scope</tt> define class methods Shirt.red and Shirt.dry_clean_only. Shirt.red,
-        # in effect, represents the query <tt>Shirt.where(:color => 'red')</tt>.
+        # The above calls to +scope+ define class methods <tt>Shirt.red</tt> and
+        # <tt>Shirt.dry_clean_only</tt>. <tt>Shirt.red</tt>, in effect,
+        # represents the query <tt>Shirt.where(color: 'red')</tt>.
         #
-        # Note that this is simply 'syntactic sugar' for defining an actual class method:
+        # You should always pass a callable object to the scopes defined
+        # with +scope+. This ensures that the scope is re-evaluated each
+        # time it is called.
+        #
+        # Note that this is simply 'syntactic sugar' for defining an actual
+        # class method:
         #
         #   class Shirt < ActiveRecord::Base
         #     def self.red
-        #       where(:color => 'red')
+        #       where(color: 'red')
         #     end
         #   end
         #
-        # 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.first</tt>, <tt>Shirt.red.count</tt>, <tt>Shirt.red.where(: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 descendant upon which
-        # the \scopes were defined. But they are also available to <tt>has_many</tt> associations. If,
+        # Unlike <tt>Shirt.find(...)</tt>, however, the object returned by
+        # <tt>Shirt.red</tt> is not an Array; it resembles the association object
+        # constructed by a +has_many+ declaration. For instance, you can invoke
+        # <tt>Shirt.red.first</tt>, <tt>Shirt.red.count</tt>,
+        # <tt>Shirt.red.where(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
+        # <tt>Shirt.red</tt> 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
+        # 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 <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
-        #     scope :colored, lambda { |color| where(:color => color) }
-        #   end
-        #
-        # In this example, <tt>Shirt.colored('puce')</tt> finds all puce shirts.
-        #
-        # On Ruby 1.9 you can use the 'stabby lambda' syntax:
-        #
-        #   scope :colored, ->(color) { where(:color => color) }
-        #
-        # Note that scopes defined with \scope will be evaluated when they are defined, rather than
-        # when they are used. For example, the following would be incorrect:
-        #
-        #   class Post < ActiveRecord::Base
-        #     scope :recent, where('published_at >= ?', Time.current - 1.week)
-        #   end
-        #
-        # The example above would be 'frozen' to the <tt>Time.current</tt> value when the <tt>Post</tt>
-        # class was defined, and so the resultant SQL query would always be the same. The correct
-        # way to do this would be via a lambda, which will re-evaluate the scope each time
-        # it is called:
-        #
-        #   class Post < ActiveRecord::Base
-        #     scope :recent, lambda { where('published_at >= ?', Time.current - 1.week) }
-        #   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 have extensions, just as with <tt>has_many</tt> declarations:
+        # \Named scopes can also have extensions, just as with +has_many+
+        # declarations:
         #
         #   class Shirt < ActiveRecord::Base
-        #     scope :red, where(:color => 'red') do
+        #     scope :red, -> { where(color: 'red') } do
         #       def dom_id
         #         'red_shirts'
         #       end
@@ -133,18 +116,18 @@ module ActiveRecord
         # Scopes can also be used while creating/building a record.
         #
         #   class Article < ActiveRecord::Base
-        #     scope :published, where(:published => true)
+        #     scope :published, -> { where(published: true) }
         #   end
         #
         #   Article.published.new.published    # => true
         #   Article.published.create.published # => true
         #
-        # Class methods on your model are automatically available
+        # \Class methods on your model are automatically available
         # on scopes. Assuming the following setup:
         #
         #   class Article < ActiveRecord::Base
-        #     scope :published, where(:published => true)
-        #     scope :featured, where(:featured => true)
+        #     scope :published, -> { where(published: true) }
+        #     scope :featured, -> { where(featured: true) }
         #
         #     def self.latest_article
         #       order('published_at desc').first