Merge the has_finder gem, renamed as 'named_scope'. Closes #11404 [nkallen]

git-svn-id: http://svn-commit.rubyonrails.org/rails/trunk@9084 5ecf4fe2-1ee6-0310-87b1-e25e094e27de

7 files changed, 147 insertions, 6 deletions

diff --git a/activerecord/lib/active_record.rb b/activerecord/lib/active_record.rb
index 4d85c24584..cedcd8b0a8 100755
--- a/activerecord/lib/active_record.rb
+++ b/activerecord/lib/active_record.rb
@@ -37,6 +37,7 @@ unless defined? ActiveSupport
 end
 
 require 'active_record/base'
+require 'active_record/named_scope'
 require 'active_record/observer'
 require 'active_record/query_cache'
 require 'active_record/validations'
@@ -64,6 +65,7 @@ ActiveRecord::Base.class_eval do
   include ActiveRecord::Observing
   include ActiveRecord::Timestamp
   include ActiveRecord::Associations
+  include ActiveRecord::NamedScope
   include ActiveRecord::AssociationPreload
   include ActiveRecord::Aggregations
   include ActiveRecord::Transactions
diff --git a/activerecord/lib/active_record/associations.rb b/activerecord/lib/active_record/associations.rb
index 068f2f9de2..e420a8ec57 100755
--- a/activerecord/lib/active_record/associations.rb
+++ b/activerecord/lib/active_record/associations.rb
@@ -1133,7 +1133,7 @@ module ActiveRecord
             end
           end
         end
-
+        
         def add_multiple_associated_save_callbacks(association_name)
           method_name = "validate_associated_records_for_#{association_name}".to_sym
           ivar = "@#{association_name}"
diff --git a/activerecord/lib/active_record/associations/association_collection.rb b/activerecord/lib/active_record/associations/association_collection.rb
index beebd72bba..d8b988d889 100644
--- a/activerecord/lib/active_record/associations/association_collection.rb
+++ b/activerecord/lib/active_record/associations/association_collection.rb
@@ -41,7 +41,7 @@ module ActiveRecord
         delete(@target)
         reset_target!
       end
-
+      
       # Calculate sum using SQL, not Enumerable
       def sum(*args)
         if block_given?
@@ -168,8 +168,10 @@ module ActiveRecord
             else
               super
             end
-          else
-            @reflection.klass.send(:with_scope, construct_scope) do
+          elsif @reflection.klass.scopes.include?(method)
+            @reflection.klass.scopes[method].call(self, *args)
+          else          
+            with_scope(construct_scope) do
               if block_given?
                 @reflection.klass.send(method, *args) { |*block_args| yield(*block_args) }
               else
diff --git a/activerecord/lib/active_record/associations/association_proxy.rb b/activerecord/lib/active_record/associations/association_proxy.rb
index adfc4610d5..421ddc15ee 100644
--- a/activerecord/lib/active_record/associations/association_proxy.rb
+++ b/activerecord/lib/active_record/associations/association_proxy.rb
@@ -119,6 +119,10 @@ module ActiveRecord
           )
         end
 
+        def with_scope(*args, &block)
+          @reflection.klass.send :with_scope, *args, &block
+        end
+          
       private
         def method_missing(method, *args)
           if load_target
diff --git a/activerecord/lib/active_record/associations/has_many_association.rb b/activerecord/lib/active_record/associations/has_many_association.rb
index 054a8991da..eedffa052b 100644
--- a/activerecord/lib/active_record/associations/has_many_association.rb
+++ b/activerecord/lib/active_record/associations/has_many_association.rb
@@ -167,7 +167,10 @@ module ActiveRecord
         def construct_scope
           create_scoping = {}
           set_belongs_to_association_for(create_scoping)
-          { :find => { :conditions => @finder_sql, :readonly => false, :order => @reflection.options[:order], :limit => @reflection.options[:limit] }, :create => create_scoping }
+          {
+            :find => { :conditions => @finder_sql, :readonly => false, :order => @reflection.options[:order], :limit => @reflection.options[:limit] },
+            :create => create_scoping
+          }
         end
     end
   end
diff --git a/activerecord/lib/active_record/associations/has_many_through_association.rb b/activerecord/lib/active_record/associations/has_many_through_association.rb
index 8c10ac641b..700a4bf89c 100644
--- a/activerecord/lib/active_record/associations/has_many_through_association.rb
+++ b/activerecord/lib/active_record/associations/has_many_through_association.rb
@@ -139,8 +139,10 @@ module ActiveRecord
             else
               super
             end
+          elsif @reflection.klass.scopes.include?(method)
+            @reflection.klass.scopes[method].call(self, *args)
           else
-            @reflection.klass.send(:with_scope, construct_scope) do
+            with_scope construct_scope do
               if block_given?
                 @reflection.klass.send(method, *args) { |*block_args| yield(*block_args) }
               else
diff --git a/activerecord/lib/active_record/named_scope.rb b/activerecord/lib/active_record/named_scope.rb
new file mode 100644
index 0000000000..120ec88f95
--- /dev/null
+++ b/activerecord/lib/active_record/named_scope.rb
@@ -0,0 +1,128 @@
+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:
+    #
+    #   Shirt.scoped(:conditions => {:color => 'red'}).scoped(:include => :washing_instructions)
+    #
+    # 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 :all
+        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 <tt>Shirt.red</tt> and <tt>Shirt.dry_clean_only</tt>. <tt>Shirt.red</tt>, 
+      # in effect, represents the query <tt>Shirt.find(:all, :conditions => {:color => 'red'})</tt>.
+      #
+      # Unlike Shirt.find(...), however, the object returned by <tt>Shirt.red</tt> 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, name scopes acts 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 were 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 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
+      #
+      def named_scope(name, options = {}, &block)
+        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
+      [].methods.each { |m| delegate m, :to => :proxy_found unless m =~ /(^__|^nil\?|^send|class|extend|find|count|sum|average|maximum|minimum|paginate)/ }
+      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
+
+      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 do
+            proxy_scope.send(method, *args, &block)
+          end
+        end
+      end
+
+      def load_found
+        @found = find(:all)
+      end
+    end
+  end
+end
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