From dca3de3bc766175f49b56202246d3625c58fd763 Mon Sep 17 00:00:00 2001
From: Pratik Naik <pratiknaik@gmail.com>
Date: Sun, 17 Jan 2010 23:22:11 +0530
Subject: Make relations work as scopes

---
 activerecord/lib/active_record/named_scope.rb      | 26 +++++++++++++++++-----
 .../lib/active_record/relation/spawn_methods.rb    | 10 ++++++---
 activerecord/test/models/post.rb                   |  8 +++----
 3 files changed, 32 insertions(+), 12 deletions(-)

diff --git a/activerecord/lib/active_record/named_scope.rb b/activerecord/lib/active_record/named_scope.rb
index 5a1cb7e769..30e75534dd 100644
--- a/activerecord/lib/active_record/named_scope.rb
+++ b/activerecord/lib/active_record/named_scope.rb
@@ -106,7 +106,7 @@ module ActiveRecord
 
         scopes[name] = lambda do |parent_scope, *args|
           Scope.new(parent_scope, case options
-            when Hash
+            when Hash, Relation
               options
             when Proc
               options.call(*args)
@@ -132,13 +132,21 @@ module ActiveRecord
       delegate :scopes, :with_scope, :scoped_methods, :unscoped, :to => :proxy_scope
 
       def initialize(proxy_scope, options, &block)
-        options ||= {}
-        [options[:extend]].flatten.each { |extension| extend extension } if options[:extend]
         extend Module.new(&block) if block_given?
+
+        options ||= {}
+        if options.is_a?(Hash)
+          Array.wrap(options[:extend]).each {|extension| extend extension }
+          @proxy_options = options.except(:extend)
+        else
+          @proxy_options = options
+        end
+
         unless Scope === proxy_scope
           @current_scoped_methods_when_defined = proxy_scope.send(:current_scoped_methods)
         end
-        @proxy_scope, @proxy_options = proxy_scope, options.except(:extend)
+
+        @proxy_scope = proxy_scope
       end
 
       def reload
@@ -193,7 +201,13 @@ module ActiveRecord
       protected
 
       def relation
-        @relation ||= unscoped.apply_finder_options(proxy_options)
+        @relation ||= begin
+          if proxy_options.is_a?(Hash)
+            unscoped.apply_finder_options(proxy_options)
+          else
+            unscoped.merge(proxy_options)
+          end
+        end
       end
 
       def proxy_found
@@ -201,6 +215,7 @@ module ActiveRecord
       end
 
       private
+
       def method_missing(method, *args, &block)
         if scopes.include?(method)
           scopes[method].call(self, *args)
@@ -221,6 +236,7 @@ module ActiveRecord
       def load_found
         @found = find(:all)
       end
+
     end
   end
 end
diff --git a/activerecord/lib/active_record/relation/spawn_methods.rb b/activerecord/lib/active_record/relation/spawn_methods.rb
index 953ea5ea1c..2979f4b82d 100644
--- a/activerecord/lib/active_record/relation/spawn_methods.rb
+++ b/activerecord/lib/active_record/relation/spawn_methods.rb
@@ -19,7 +19,10 @@ module ActiveRecord
         raise ArgumentError, "Cannot merge a #{r.klass.name}(##{r.klass.object_id}) relation with #{@klass.name}(##{@klass.object_id}) relation"
       end
 
-      merged_relation = spawn.eager_load(r.eager_load_values).preload(r.preload_values).includes(r.includes_values)
+      merged_relation = spawn
+      return merged_relation unless r
+
+      merged_relation = merged_relation.eager_load(r.eager_load_values).preload(r.preload_values).includes(r.includes_values)
 
       merged_relation.readonly_value = r.readonly_value unless r.readonly_value.nil?
       merged_relation.limit_value = r.limit_value if r.limit_value.present?
@@ -94,9 +97,10 @@ module ActiveRecord
                            :order, :select, :readonly, :group, :having, :from, :lock ]
 
     def apply_finder_options(options)
-      options.assert_valid_keys(VALID_FIND_OPTIONS)
-
       relation = spawn
+      return relation unless options
+
+      options.assert_valid_keys(VALID_FIND_OPTIONS)
 
       relation = relation.joins(options[:joins]).
         where(options[:conditions]).
diff --git a/activerecord/test/models/post.rb b/activerecord/test/models/post.rb
index 662f75c39f..b5f9328139 100644
--- a/activerecord/test/models/post.rb
+++ b/activerecord/test/models/post.rb
@@ -1,7 +1,7 @@
 class Post < ActiveRecord::Base
-  named_scope :containing_the_letter_a, :conditions => "body LIKE '%a%'"
-  named_scope :ranked_by_comments, :order => "comments_count DESC"
-  named_scope :limit_by, lambda {|limit| {:limit => limit} }
+  named_scope :containing_the_letter_a, where("body LIKE '%a%'")
+  named_scope :ranked_by_comments, order("comments_count DESC")
+  named_scope :limit_by, lambda {|l| limit(l) }
   named_scope :with_authors_at_address, lambda { |address| {
       :conditions => [ 'authors.author_address_id = ?', address.id ],
       :joins => 'JOIN authors ON authors.id = posts.author_id'
@@ -20,7 +20,7 @@ class Post < ActiveRecord::Base
   has_one :last_comment, :class_name => 'Comment', :order => 'id desc'
 
   named_scope :with_special_comments, :joins => :comments, :conditions => {:comments => {:type => 'SpecialComment'} }
-  named_scope :with_very_special_comments, :joins => :comments, :conditions => {:comments => {:type => 'VerySpecialComment'} }
+  named_scope :with_very_special_comments, joins(:comments).where(:comments => {:type => 'VerySpecialComment'})
   named_scope :with_post, lambda {|post_id|
     { :joins => :comments, :conditions => {:comments => {:post_id => post_id} } }
   }
-- 
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