Fixed eager loading problems with single-table inheritance [Rick Olson] Added smarter table aliasing for eager associations for multiple self joins [Rick Olson] (closes #3580)

git-svn-id: http://svn-commit.rubyonrails.org/rails/trunk@3776 5ecf4fe2-1ee6-0310-87b1-e25e094e27de

10 files changed, 144 insertions, 63 deletions

diff --git a/activerecord/CHANGELOG b/activerecord/CHANGELOG
index 95544950e9..9114f70ea1 100644
--- a/activerecord/CHANGELOG
+++ b/activerecord/CHANGELOG
@@ -1,5 +1,16 @@
 *SVN*
 
+* Added smarter table aliasing for eager associations for multiple self joins #3580 [Rick Olson]
+
+    * The first time a table is referenced in a join, no alias is used.
+    * After that, the parent table name and the reflection name are used.
+    
+        Tree.find(:all, :include => :children) # LEFT OUTER JOIN trees AS tress_children ...
+    
+    * Any additional join references get a numerical suffix like '_2', '_3', etc.
+
+* Fixed eager loading problems with single-table inheritance #3580 [Rick Olson]. Post.find(:all, :include => :special_comments) now returns all posts, and any special comments that the posts may have. And made STI work with has_many :through and polymorphic belongs_to.
+
 * Added cascading eager loading that allows for queries like Author.find(:all, :include=> { :posts=> :comments }), which will fetch all authors, their posts, and the comments belonging to those posts in a single query (using LEFT OUTER JOIN) #3913 [anna@wota.jp]. Examples:
 
     # cascaded in two levels
diff --git a/activerecord/lib/active_record/associations.rb b/activerecord/lib/active_record/associations.rb
index 5454631999..d31d43c800 100755
--- a/activerecord/lib/active_record/associations.rb
+++ b/activerecord/lib/active_record/associations.rb
@@ -932,7 +932,6 @@ module ActiveRecord
           sql << "#{options[:joins]} " if options[:joins]
 
           add_conditions!(sql, options[:conditions])
-          add_sti_conditions!(sql, join_dependency)
           add_limited_ids_condition!(sql, options, join_dependency) if !using_limitable_reflections?(join_dependency.reflections) && options[:limit]
 
           add_limit!(sql, options) if using_limitable_reflections?(join_dependency.reflections)
@@ -950,7 +949,6 @@ module ActiveRecord
           sql << "#{options[:joins]} " if options[:joins]
  
           add_conditions!(sql, options[:conditions])
-          add_sti_conditions!(sql, join_dependency)
           add_limited_ids_condition!(sql, options, join_dependency) if !using_limitable_reflections?(join_dependency.reflections) && options[:limit]
 
           sql << "ORDER BY #{options[:order]} " if options[:order]
@@ -1011,41 +1009,6 @@ module ActiveRecord
           reflections.reject { |r| [ :belongs_to, :has_one ].include?(r.macro) }.length.zero?
         end
 
-        def join_depended_type_condition (klass, join_dependency)
-          aliased_table_name = join_dependency.aliased_table_names_for(klass.table_name).last || klass.table_name
-          quoted_inheritance_column = connection.quote_column_name(klass.inheritance_column)
-          type_condition = klass.subclasses.inject(sti_condition(klass, aliased_table_name, quoted_inheritance_column)) do |condition, subclass|
-            condition << " OR #{sti_condition subclass, aliased_table_name, quoted_inheritance_column}"
-          end
-        
-          " (#{type_condition}) "
-        end
-        
-        def sti_condition(klass, table_name, inheritance_column)
-          "(#{table_name}.#{inheritance_column} = '#{klass.name.demodulize}' OR #{table_name}.#{inheritance_column} IS NULL)"
-        end
-
-        #def join_depended_type_condition (klass, join_dependency)
-        #  aliased_table_name = join_dependency.aliased_table_names_for(klass.table_name).first || klass.table_name
-        #  quoted_inheritance_column = connection.quote_column_name(klass.inheritance_column)
-        #  type_condition = klass.subclasses.inject("#{aliased_table_name}.#{quoted_inheritance_column} = '#{klass.name.demodulize}' ") do |condition, subclass|
-        #    condition << "OR #{aliased_table_name}.#{quoted_inheritance_column} = '#{subclass.name.demodulize}' "
-        #  end
-        #
-        #  " (#{type_condition}) "
-        #end
-
-        def add_sti_conditions!(sql, join_dependency)
-          reflections = join_dependency.reflections
-          sti_conditions = reflections.collect do |reflection|
-            join_depended_type_condition(reflection.klass, join_dependency) unless reflection.klass.descends_from_active_record?
-          end.compact
-          
-          unless sti_conditions.empty?
-            sql << condition_word(sql) + sti_conditions.join(" AND ")
-          end
-        end
-
         def column_aliases(join_dependency)
           join_dependency.joins.collect{|join| join.column_names_with_alias.collect{|column_name, aliased_name|
               "#{join.aliased_table_name}.#{connection.quote_column_name column_name} AS #{aliased_name}"}}.flatten.join(", ")
@@ -1078,7 +1041,7 @@ module ActiveRecord
         end
 
         class JoinDependency
-          attr_reader :joins, :reflections
+          attr_reader :joins, :reflections, :table_aliases
 
           def initialize(base, associations)
             @joins                 = [JoinBase.new(base)]
@@ -1086,6 +1049,8 @@ module ActiveRecord
             @reflections           = []
             @base_records_hash     = {}
             @base_records_in_order = []
+            @table_aliases         = Hash.new { |aliases, table| aliases[table] = 0 }
+            @table_aliases[base.table_name] = 1
             build(associations)
           end
 
@@ -1228,26 +1193,65 @@ module ActiveRecord
               @parent             = parent
               @reflection         = reflection
               @aliased_prefix     = "t#{ join_dependency.joins.size }"
-              @aliased_table_name = join_dependency.aliased_table_names_for(table_name).empty? ? table_name : @aliased_prefix
+              @aliased_table_name = table_name # start with the table name
+              unless join_dependency.table_aliases[aliased_table_name].zero?
+                # if the table name has been used, then use an alias
+                # if the alias has been used, add a '_n' suffix to the end.
+                @aliased_table_name = "#{parent.table_name}_#{reflection.name}_#{join_dependency.table_aliases[aliased_table_name]}".gsub(/_1$/, '')
+              end
+              join_dependency.table_aliases[aliased_table_name] += 1
             end
 
             def association_join
-              case reflection.macro
+              join = case reflection.macro
                 when :has_and_belongs_to_many
                   join_table_name    =
                   " LEFT OUTER JOIN %s ON %s.%s = %s.%s " % [
                      options[:join_table], options[:join_table],
                      options[:foreign_key] || reflection.active_record.to_s.classify.foreign_key,
                      reflection.active_record.table_name, reflection.active_record.primary_key] +
-                  " LEFT OUTER JOIN %s ON %s.%s = %s.%s " % [
-                     aliased_table_name, aliased_table_name, klass.primary_key,
+                  " LEFT OUTER JOIN %s AS %s ON %s.%s = %s.%s " % [
+                     table_name, aliased_table_name, aliased_table_name, klass.primary_key,
                      options[:join_table], options[:association_foreign_key] || klass.table_name.classify.foreign_key
                      ]
                 when :has_many, :has_one
-                  " LEFT OUTER JOIN %s AS %s ON %s.%s = %s.%s " % [table_name, aliased_table_name,
-                     aliased_table_name, options[:foreign_key] || reflection.active_record.to_s.classify.foreign_key,
-                     parent.aliased_table_name, parent.primary_key
-                    ]
+                  case
+                    when reflection.macro == :has_many && reflection.options[:through]
+                      through_reflection       = parent.active_record.reflect_on_association(reflection.options[:through])
+                      aliased_through_table    = "#{parent.table_name}_#{through_reflection.klass.table_name}"
+                      if through_reflection.options[:as] # has_many :through against a polymorphic join
+                        polymorphic_foreign_key  = through_reflection.options[:as].to_s + '_id'
+                        polymorphic_foreign_type = through_reflection.options[:as].to_s + '_type'
+
+                        " LEFT OUTER JOIN %s AS %s ON (%s.%s = %s.%s AND %s.%s = %s) "  % [through_reflection.klass.table_name, aliased_through_table,
+                          aliased_through_table, polymorphic_foreign_key,
+                          parent.aliased_table_name, parent.primary_key,
+                          aliased_through_table, polymorphic_foreign_type, reflection.klass.quote(parent.active_record.base_class.name)] +
+                        " LEFT OUTER JOIN %s AS %s ON %s.%s = %s.%s " % [table_name, aliased_table_name,
+                          aliased_table_name, primary_key, aliased_through_table, options[:foreign_key] || reflection.klass.to_s.classify.foreign_key
+                        ]
+                      else # has_many :through against a normal join
+                        " LEFT OUTER JOIN %s AS %s ON %s.%s = %s.%s "  % [through_reflection.klass.table_name, aliased_through_table,
+                          aliased_through_table, through_reflection.options[:foreign_key] || through_reflection.active_record.to_s.classify.foreign_key,
+                          parent.aliased_table_name, parent.primary_key] +
+                        " LEFT OUTER JOIN %s AS %s ON %s.%s = %s.%s " % [table_name, aliased_table_name,
+                          aliased_table_name, primary_key, aliased_through_table, options[:foreign_key] || reflection.klass.to_s.classify.foreign_key
+                        ]
+                      end
+                      
+                    when reflection.macro == :has_many && reflection.options[:as]
+                      " LEFT OUTER JOIN %s AS %s ON %s.%s = %s.%s AND %s.%s = %s" % [table_name, aliased_table_name,
+                        aliased_table_name, "#{reflection.options[:as]}_id",
+                        parent.aliased_table_name, parent.primary_key,
+                        aliased_table_name, "#{reflection.options[:as]}_type",
+                        reflection.klass.quote(parent.active_record.base_class.name)
+                      ]
+                    else
+                      " LEFT OUTER JOIN %s AS %s ON %s.%s = %s.%s " % [table_name, aliased_table_name,
+                        aliased_table_name, options[:foreign_key] || reflection.active_record.to_s.classify.foreign_key,
+                        parent.aliased_table_name, parent.primary_key
+                      ]
+                  end
                 when :belongs_to
                   " LEFT OUTER JOIN %s AS %s ON %s.%s = %s.%s " % [table_name, aliased_table_name,
                      aliased_table_name, reflection.klass.primary_key,
@@ -1256,6 +1260,11 @@ module ActiveRecord
                 else
                   ""
               end
+              join << %(AND %s."%s" = %s ) % [
+                aliased_table_name, 
+                reflection.active_record.inheritance_column, 
+                reflection.klass.quote(klass.name)] unless join.blank? || reflection.klass.descends_from_active_record?
+              join
             end
           end
         end
diff --git a/activerecord/test/abstract_unit.rb b/activerecord/test/abstract_unit.rb
index 1bd2f6baaf..70487980c5 100755
--- a/activerecord/test/abstract_unit.rb
+++ b/activerecord/test/abstract_unit.rb
@@ -29,6 +29,19 @@ class Test::Unit::TestCase #:nodoc:
       assert_equal expected.to_s, actual.to_s, message
     end
   end
+
+  def assert_no_queries
+    ActiveRecord::Base.connection.class.class_eval do
+      self.query_count = 0
+      alias_method :execute, :execute_with_query_counting
+    end
+    yield
+  ensure
+    ActiveRecord::Base.connection.class.class_eval do
+      alias_method :execute, :execute_without_query_counting
+    end
+    assert_equal 0, ActiveRecord::Base.connection.query_count, "1 or more queries were executed"
+  end
 end
 
 def current_adapter?(type)
@@ -36,5 +49,14 @@ def current_adapter?(type)
     ActiveRecord::Base.connection.instance_of?(ActiveRecord::ConnectionAdapters.const_get(type))
 end
 
+ActiveRecord::Base.connection.class.class_eval do
+  cattr_accessor :query_count
+  alias_method :execute_without_query_counting, :execute
+  def execute_with_query_counting(sql, name = nil)
+    self.query_count += 1
+    execute_without_query_counting(sql, name)
+  end
+end
+
 #ActiveRecord::Base.logger = Logger.new(STDOUT)
 #ActiveRecord::Base.colorize_logging = false
diff --git a/activerecord/test/associations_cascaded_eager_loading_test.rb b/activerecord/test/associations_cascaded_eager_loading_test.rb
index 797bc85bc3..8f0a41f593 100644
--- a/activerecord/test/associations_cascaded_eager_loading_test.rb
+++ b/activerecord/test/associations_cascaded_eager_loading_test.rb
@@ -56,23 +56,33 @@ class CascadedEagerLoadingTest < Test::Unit::TestCase
   def test_eager_association_loading_with_acts_as_tree
     roots = TreeMixin.find(:all, :include=>"children", :conditions=>"mixins.parent_id IS NULL", :order=>"mixins.id")
     assert_equal [mixins(:tree_1), mixins(:tree2_1), mixins(:tree3_1)], roots
-    assert_equal 2, roots[0].children.size
-    assert_equal 0, roots[1].children.size
-    assert_equal 0, roots[2].children.size
+    assert_no_queries do
+      assert_equal 2, roots[0].children.size
+      assert_equal 0, roots[1].children.size
+      assert_equal 0, roots[2].children.size
+    end
   end
 
   def test_eager_association_loading_with_cascaded_three_levels_by_ping_pong
     firms = Firm.find(:all, :include=>{:account=>{:firm=>:account}}, :order=>"companies.id")
     assert_equal 2, firms.size
     assert_equal firms.first.account, firms.first.account.firm.account
-    assert_equal companies(:first_firm).account, firms.first.account.firm.account
-    assert_equal companies(:first_firm).account.firm.account, firms.first.account.firm.account
+    assert_equal companies(:first_firm).account, assert_no_queries { firms.first.account.firm.account }
+    assert_equal companies(:first_firm).account.firm.account, assert_no_queries { firms.first.account.firm.account }
   end
 
-  def test_eager_association_loading_with_sti
+  def test_eager_association_loading_with_has_many_sti
     topics = Topic.find(:all, :include => :replies, :order => 'topics.id')
     assert_equal [topics(:first), topics(:second)], topics
-    assert_equal 1, topics[0].replies.size
-    assert_equal 0, topics[1].replies.size
+    assert_no_queries do
+      assert_equal 1, topics[0].replies.size
+      assert_equal 0, topics[1].replies.size
+    end
+  end
+
+  def test_eager_association_loading_with_belongs_to_sti
+    replies = Reply.find(:all, :include => :topic, :order => 'topics.id')
+    assert_equal [topics(:second)], replies
+    assert_equal topics(:first), assert_no_queries { replies.first.topic }
   end
 end
diff --git a/activerecord/test/associations_go_eager_test.rb b/activerecord/test/associations_go_eager_test.rb
index 2212596099..50cb9bec59 100644
--- a/activerecord/test/associations_go_eager_test.rb
+++ b/activerecord/test/associations_go_eager_test.rb
@@ -94,13 +94,13 @@ class EagerAssociationTest < Test::Unit::TestCase
   def test_eager_association_loading_with_belongs_to_and_limit_and_multiple_associations
     posts = Post.find(:all, :include => [:author, :very_special_comment], :limit => 1, :order => 'posts.id')
     assert_equal 1, posts.length
-    assert_equal [3], posts.collect { |p| p.id }
+    assert_equal [1], posts.collect { |p| p.id }
   end
   
   def test_eager_association_loading_with_belongs_to_and_limit_and_offset_and_multiple_associations
     posts = Post.find(:all, :include => [:author, :very_special_comment], :limit => 1, :offset => 1, :order => 'posts.id')
     assert_equal 1, posts.length
-    assert_equal [4], posts.collect { |p| p.id }
+    assert_equal [2], posts.collect { |p| p.id }
   end
   
   def test_eager_with_has_many_through
@@ -108,8 +108,8 @@ class EagerAssociationTest < Test::Unit::TestCase
     posts_with_author = people(:michael).posts.find(:all, :include => :author )
     posts_with_comments_and_author = people(:michael).posts.find(:all, :include => [ :comments, :author ])
     assert_equal 2, posts_with_comments.inject(0) { |sum, post| sum += post.comments.size }
-    assert_equal authors(:david), posts_with_author.first.author
-    assert_equal authors(:david), posts_with_comments_and_author.first.author
+    assert_equal authors(:david), assert_no_queries { posts_with_author.first.author }
+    assert_equal authors(:david), assert_no_queries { posts_with_comments_and_author.first.author }
   end
 
   def test_eager_with_has_many_and_limit
diff --git a/activerecord/test/associations_join_model_test.rb b/activerecord/test/associations_join_model_test.rb
index a2f42f060e..b14693d7a6 100644
--- a/activerecord/test/associations_join_model_test.rb
+++ b/activerecord/test/associations_join_model_test.rb
@@ -81,7 +81,34 @@ class AssociationsJoinModelTest < Test::Unit::TestCase
   def test_has_many_with_piggyback
     assert_equal "2", categories(:sti_test).authors.first.post_id.to_s
   end
-  
+
+  def test_include_has_many_through
+    posts              = Post.find(:all, :order => 'posts.id')
+    posts_with_authors = Post.find(:all, :include => :authors, :order => 'posts.id')
+    assert_equal posts.length, posts_with_authors.length
+    posts.length.times do |i|
+      assert_equal posts[i].authors.length, assert_no_queries { posts_with_authors[i].authors.length }
+    end
+  end
+
+  def test_include_polymorphic_has_many_through
+    posts           = Post.find(:all, :order => 'posts.id')
+    posts_with_tags = Post.find(:all, :include => :tags, :order => 'posts.id')
+    assert_equal posts.length, posts_with_tags.length
+    posts.length.times do |i|
+      assert_equal posts[i].tags.length, assert_no_queries { posts_with_tags[i].tags.length }
+    end
+  end
+
+  def test_include_polymorphic_has_many
+    posts               = Post.find(:all, :order => 'posts.id')
+    posts_with_taggings = Post.find(:all, :include => :taggings, :order => 'posts.id')
+    assert_equal posts.length, posts_with_taggings.length
+    posts.length.times do |i|
+      assert_equal posts[i].taggings.length, assert_no_queries { posts_with_taggings[i].taggings.length }
+    end
+  end
+
   def test_has_many_find_all
     assert_equal [categories(:general)], authors(:david).categories.find(:all)
   end
diff --git a/activerecord/test/base_test.rb b/activerecord/test/base_test.rb
index a84e0ed5e8..c5834f2e5b 100755
--- a/activerecord/test/base_test.rb
+++ b/activerecord/test/base_test.rb
@@ -567,7 +567,7 @@ class BasicsTest < Test::Unit::TestCase
   end
 
   def test_equality
-    assert_equal Topic.find(1), Topic.find(2).parent
+    assert_equal Topic.find(1), Topic.find(2).topic
   end
   
   def test_equality_of_new_records
@@ -575,7 +575,7 @@ class BasicsTest < Test::Unit::TestCase
   end
   
   def test_hashing
-    assert_equal [ Topic.find(1) ], [ Topic.find(2).parent ] & [ Topic.find(1) ]
+    assert_equal [ Topic.find(1) ], [ Topic.find(2).topic ] & [ Topic.find(1) ]
   end
   
   def test_destroy_new_record
diff --git a/activerecord/test/finder_test.rb b/activerecord/test/finder_test.rb
index 26a4688108..bf7237b684 100644
--- a/activerecord/test/finder_test.rb
+++ b/activerecord/test/finder_test.rb
@@ -1,6 +1,7 @@
 require 'abstract_unit'
 require 'fixtures/company'
 require 'fixtures/topic'
+require 'fixtures/reply'
 require 'fixtures/entrant'
 require 'fixtures/developer'
 require 'fixtures/post'
@@ -92,7 +93,7 @@ class FinderTest < Test::Unit::TestCase
       Topic.find(1).parent
     }
     
-    Topic.find(2).parent
+    Topic.find(2).topic
   end
   
   def test_find_only_some_columns
diff --git a/activerecord/test/fixtures/topic.rb b/activerecord/test/fixtures/topic.rb
index 4c46122450..1941080ec7 100755
--- a/activerecord/test/fixtures/topic.rb
+++ b/activerecord/test/fixtures/topic.rb
@@ -6,7 +6,7 @@ class Topic < ActiveRecord::Base
   before_destroy :destroy_children
 
   def parent
-    self.class.find(parent_id)
+    Topic.find(parent_id)
   end
   
   protected
diff --git a/activerecord/test/fixtures/topics.yml b/activerecord/test/fixtures/topics.yml
index 6d4f5d800b..810bbcf4e8 100644
--- a/activerecord/test/fixtures/topics.yml
+++ b/activerecord/test/fixtures/topics.yml
@@ -19,3 +19,4 @@ second:
   approved: true
   replies_count: 2
   parent_id: 1
+  type: Reply