Allow overriding of find parameters in scoped has_many :through calls [Rick Olson]

git-svn-id: http://svn-commit.rubyonrails.org/rails/trunk@4007 5ecf4fe2-1ee6-0310-87b1-e25e094e27de

activerecord/CHANGELOG

 *SVN*
 
+* Allow overriding of find parameters in scoped has_many :through calls [Rick Olson]
+
+  In this example, :include => false disables the default eager association from loading.  :select changes the standard
+  select clause.  :joins specifies a join that is added to the end of the has_many :through query.
+  
+    class Post < ActiveRecord::Base
+      has_many :tags, :through => :taggings, :include => :tagging do
+        def add_joins_and_select
+          find :all, :select => 'tags.*, authors.id as author_id', :include => false,
+            :joins => 'left outer join posts on taggings.taggable_id = posts.id left outer join authors on posts.author_id = authors.id'
+        end
+      end
+    end
+    
 * Fixed that schema changes while the database was open would break any connections to a SQLite database (now we reconnect if that error is throw) [DHH]
 
 * Don't classify the has_one class when eager loading, it is already singular. Add tests. (closes #4117) [jonathan@bluewire.net.nz]

activerecord/lib/active_record/associations/has_many_through_association.rb

@@ -24,10 +24,10 @@ def find(*args)
           options[:order] = @reflection.options[:order]
         end
         
-        options[:select]    = construct_select
-        options[:from]      = construct_from
-        options[:joins]     = construct_joins
-        options[:include] ||= @reflection.source_reflection.options[:include]
+        options[:select]  = construct_select(options[:select])
+        options[:from]  ||= construct_from
+        options[:joins]   = construct_joins(options[:joins])
+        options[:include] = @reflection.source_reflection.options[:include] if options[:include].nil?
         
         merge_options_from_reflection!(options)
 
@@ -84,11 +84,11 @@ def construct_from
           @reflection.table_name
         end
         
-        def construct_select
-          selected = @reflection.options[:select] || "#{@reflection.table_name}.*"          
+        def construct_select(custom_select = nil)
+          selected = custom_select || @reflection.options[:select] || "#{@reflection.table_name}.*"          
         end
         
-        def construct_joins
+        def construct_joins(custom_joins = nil)
           if @reflection.through_reflection.options[:as] || @reflection.source_reflection.macro == :belongs_to
             reflection_primary_key = @reflection.klass.primary_key
             source_primary_key     = @reflection.source_reflection.primary_key_name
@@ -96,8 +96,8 @@ def construct_joins
             reflection_primary_key = @reflection.source_reflection.primary_key_name
             source_primary_key     = @reflection.klass.primary_key
           end
-          
-          "INNER JOIN %s ON %s.%s = %s.%s #{@reflection.options[:joins]}" % [
+
+          "INNER JOIN %s ON %s.%s = %s.%s #{@reflection.options[:joins]} #{custom_joins}" % [
             @reflection.through_reflection.table_name,
             @reflection.table_name, reflection_primary_key,
             @reflection.through_reflection.table_name, source_primary_key

activerecord/test/associations_join_model_test.rb

@@ -63,6 +63,17 @@ def test_polymorphic_has_many_going_through_join_model_with_include_on_source_re
     end
   end
 
+  def test_polymorphic_has_many_going_through_join_model_with_disabled_include
+    assert_equal tags(:general), tag = posts(:welcome).tags.add_joins_and_select.first
+    assert_queries 1 do
+      tag.tagging
+    end
+  end
+
+  def test_polymorphic_has_many_going_through_join_model_with_custom_select_and_joins
+    assert_equal tags(:general), tag = posts(:welcome).tags.add_joins_and_select.first
+    tag.author_id
+  end
 
   def test_polymorphic_has_many_going_through_join_model_with_custom_foreign_key
     assert_equal tags(:misc), taggings(:welcome_general).super_tag

activerecord/test/fixtures/post.rb

@@ -21,7 +21,13 @@ def find_most_recent
   has_and_belongs_to_many :special_categories, :join_table => "categories_posts", :association_foreign_key => 'category_id'
 
   has_many :taggings, :as => :taggable
-  has_many :tags, :through => :taggings, :include => :tagging
+  has_many :tags, :through => :taggings, :include => :tagging do
+    def add_joins_and_select
+      find :all, :select => 'tags.*, authors.id as author_id', :include => false,
+        :joins => 'left outer join posts on taggings.taggable_id = posts.id left outer join authors on posts.author_id = authors.id'
+    end
+  end
+  
   has_many :funky_tags, :through => :taggings, :class_name => 'Tag'
   has_many :super_tags, :through => :taggings
   has_one :tagging, :as => :taggable