Merge branch 'master' into nested_has_many_through

Conflicts:
	activerecord/CHANGELOG
	activerecord/lib/active_record/association_preload.rb
	activerecord/lib/active_record/associations.rb
	activerecord/lib/active_record/associations/class_methods/join_dependency.rb
	activerecord/lib/active_record/associations/class_methods/join_dependency/join_association.rb
	activerecord/lib/active_record/associations/has_many_association.rb
	activerecord/lib/active_record/associations/has_many_through_association.rb
	activerecord/lib/active_record/associations/has_one_association.rb
	activerecord/lib/active_record/associations/has_one_through_association.rb
	activerecord/lib/active_record/associations/through_association_scope.rb
	activerecord/lib/active_record/reflection.rb
	activerecord/test/cases/associations/has_many_through_associations_test.rb
	activerecord/test/cases/associations/has_one_through_associations_test.rb
	activerecord/test/cases/reflection_test.rb
	activerecord/test/cases/relations_test.rb
	activerecord/test/fixtures/memberships.yml
	activerecord/test/models/categorization.rb
	activerecord/test/models/category.rb
	activerecord/test/models/member.rb
	activerecord/test/models/reference.rb
	activerecord/test/models/tagging.rb

10 files changed, 377 insertions, 0 deletions

diff --git a/activerecord/lib/active_record/associations/preloader/association.rb b/activerecord/lib/active_record/associations/preloader/association.rb
new file mode 100644
index 0000000000..7256dd5288
--- /dev/null
+++ b/activerecord/lib/active_record/associations/preloader/association.rb
@@ -0,0 +1,126 @@
+module ActiveRecord
+  module Associations
+    class Preloader
+      class Association #:nodoc:
+        attr_reader :owners, :reflection, :preload_options, :model, :klass
+
+        def initialize(klass, owners, reflection, preload_options)
+          @klass           = klass
+          @owners          = owners
+          @reflection      = reflection
+          @preload_options = preload_options || {}
+          @model           = owners.first && owners.first.class
+          @scoped          = nil
+          @owners_by_key   = nil
+        end
+
+        def run
+          unless owners.first.association(reflection.name).loaded?
+            preload
+          end
+        end
+
+        def preload
+          raise NotImplementedError
+        end
+
+        def scoped
+          @scoped ||= build_scope
+        end
+
+        def records_for(ids)
+          scoped.where(association_key.in(ids))
+        end
+
+        def table
+          klass.arel_table
+        end
+
+        # The name of the key on the associated records
+        def association_key_name
+          raise NotImplementedError
+        end
+
+        # This is overridden by HABTM as the condition should be on the foreign_key column in
+        # the join table
+        def association_key
+          table[association_key_name]
+        end
+
+        # The name of the key on the model which declares the association
+        def owner_key_name
+          raise NotImplementedError
+        end
+
+        # We're converting to a string here because postgres will return the aliased association
+        # key in a habtm as a string (for whatever reason)
+        def owners_by_key
+          @owners_by_key ||= owners.group_by do |owner|
+            key = owner[owner_key_name]
+            key && key.to_s
+          end
+        end
+
+        def options
+          reflection.options
+        end
+
+        private
+
+        def associated_records_by_owner
+          owner_keys = owners.map { |owner| owner[owner_key_name] }.compact.uniq
+
+          if klass.nil? || owner_keys.empty?
+            records = []
+          else
+            # Some databases impose a limit on the number of ids in a list (in Oracle it's 1000)
+            # Make several smaller queries if necessary or make one query if the adapter supports it
+            sliced  = owner_keys.each_slice(model.connection.in_clause_length || owner_keys.size)
+            records = sliced.map { |slice| records_for(slice) }.flatten
+          end
+
+          # Each record may have multiple owners, and vice-versa
+          records_by_owner = Hash[owners.map { |owner| [owner, []] }]
+          records.each do |record|
+            owner_key = record[association_key_name].to_s
+
+            owners_by_key[owner_key].each do |owner|
+              records_by_owner[owner] << record
+            end
+          end
+          records_by_owner
+        end
+
+        def build_scope
+          scope = klass.scoped
+
+          scope = scope.where(process_conditions(options[:conditions]))
+          scope = scope.where(process_conditions(preload_options[:conditions]))
+
+          scope = scope.select(preload_options[:select] || options[:select] || table[Arel.star])
+          scope = scope.includes(preload_options[:include] || options[:include])
+
+          if options[:as]
+            scope = scope.where(
+              klass.table_name => {
+                reflection.type => model.base_class.sti_name
+              }
+            )
+          end
+
+          scope
+        end
+
+        def process_conditions(conditions)
+          if conditions.respond_to?(:to_proc)
+            conditions = klass.send(:instance_eval, &conditions)
+          end
+
+          if conditions
+            klass.send(:sanitize_sql, conditions)
+          end
+        end
+      end
+    end
+  end
+end
diff --git a/activerecord/lib/active_record/associations/preloader/belongs_to.rb b/activerecord/lib/active_record/associations/preloader/belongs_to.rb
new file mode 100644
index 0000000000..5091d4717a
--- /dev/null
+++ b/activerecord/lib/active_record/associations/preloader/belongs_to.rb
@@ -0,0 +1,17 @@
+module ActiveRecord
+  module Associations
+    class Preloader
+      class BelongsTo < SingularAssociation #:nodoc:
+
+        def association_key_name
+          reflection.options[:primary_key] || klass && klass.primary_key
+        end
+
+        def owner_key_name
+          reflection.foreign_key
+        end
+
+      end
+    end
+  end
+end
diff --git a/activerecord/lib/active_record/associations/preloader/collection_association.rb b/activerecord/lib/active_record/associations/preloader/collection_association.rb
new file mode 100644
index 0000000000..c248aeaaf6
--- /dev/null
+++ b/activerecord/lib/active_record/associations/preloader/collection_association.rb
@@ -0,0 +1,24 @@
+module ActiveRecord
+  module Associations
+    class Preloader
+      class CollectionAssociation < Association #:nodoc:
+
+        private
+
+        def build_scope
+          super.order(preload_options[:order] || options[:order])
+        end
+
+        def preload
+          associated_records_by_owner.each do |owner, records|
+            association = owner.association(reflection.name)
+            association.loaded!
+            association.target.concat(records)
+            records.each { |record| association.set_inverse_instance(record) }
+          end
+        end
+
+      end
+    end
+  end
+end
diff --git a/activerecord/lib/active_record/associations/preloader/has_and_belongs_to_many.rb b/activerecord/lib/active_record/associations/preloader/has_and_belongs_to_many.rb
new file mode 100644
index 0000000000..e794f05340
--- /dev/null
+++ b/activerecord/lib/active_record/associations/preloader/has_and_belongs_to_many.rb
@@ -0,0 +1,58 @@
+module ActiveRecord
+  module Associations
+    class Preloader
+      class HasAndBelongsToMany < CollectionAssociation #:nodoc:
+        attr_reader :join_table
+
+        def initialize(klass, records, reflection, preload_options)
+          super
+          @join_table = Arel::Table.new(options[:join_table]).alias('t0')
+        end
+
+        # Unlike the other associations, we want to get a raw array of rows so that we can
+        # access the aliased column on the join table
+        def records_for(ids)
+          scope = super
+          klass.connection.select_all(scope.arel.to_sql, 'SQL', scope.bind_values)
+        end
+
+        def owner_key_name
+          reflection.active_record_primary_key
+        end
+
+        def association_key_name
+          'ar_association_key_name'
+        end
+
+        def association_key
+          join_table[reflection.foreign_key]
+        end
+
+        private
+
+        # Once we have used the join table column (in super), we manually instantiate the
+        # actual records
+        def associated_records_by_owner
+          super.each do |owner_key, rows|
+            rows.map! { |row| klass.instantiate(row) }
+          end
+        end
+
+        def build_scope
+          super.joins(join).select(join_select)
+        end
+
+        def join_select
+          association_key.as(Arel.sql(association_key_name))
+        end
+
+        def join
+          condition = table[reflection.association_primary_key].eq(
+            join_table[reflection.association_foreign_key])
+
+          table.create_join(join_table, table.create_on(condition))
+        end
+      end
+    end
+  end
+end
diff --git a/activerecord/lib/active_record/associations/preloader/has_many.rb b/activerecord/lib/active_record/associations/preloader/has_many.rb
new file mode 100644
index 0000000000..3ea91a8c11
--- /dev/null
+++ b/activerecord/lib/active_record/associations/preloader/has_many.rb
@@ -0,0 +1,17 @@
+module ActiveRecord
+  module Associations
+    class Preloader
+      class HasMany < CollectionAssociation #:nodoc:
+
+        def association_key_name
+          reflection.foreign_key
+        end
+
+        def owner_key_name
+          reflection.active_record_primary_key
+        end
+
+      end
+    end
+  end
+end
diff --git a/activerecord/lib/active_record/associations/preloader/has_many_through.rb b/activerecord/lib/active_record/associations/preloader/has_many_through.rb
new file mode 100644
index 0000000000..c6e9ede356
--- /dev/null
+++ b/activerecord/lib/active_record/associations/preloader/has_many_through.rb
@@ -0,0 +1,15 @@
+module ActiveRecord
+  module Associations
+    class Preloader
+      class HasManyThrough < CollectionAssociation #:nodoc:
+        include ThroughAssociation
+
+        def associated_records_by_owner
+          super.each do |owner, records|
+            records.uniq! if options[:uniq]
+          end
+        end
+      end
+    end
+  end
+end
diff --git a/activerecord/lib/active_record/associations/preloader/has_one.rb b/activerecord/lib/active_record/associations/preloader/has_one.rb
new file mode 100644
index 0000000000..848448bb48
--- /dev/null
+++ b/activerecord/lib/active_record/associations/preloader/has_one.rb
@@ -0,0 +1,23 @@
+module ActiveRecord
+  module Associations
+    class Preloader
+      class HasOne < SingularAssociation #:nodoc:
+
+        def association_key_name
+          reflection.foreign_key
+        end
+
+        def owner_key_name
+          reflection.active_record_primary_key
+        end
+
+        private
+
+        def build_scope
+          super.order(preload_options[:order] || options[:order])
+        end
+
+      end
+    end
+  end
+end
diff --git a/activerecord/lib/active_record/associations/preloader/has_one_through.rb b/activerecord/lib/active_record/associations/preloader/has_one_through.rb
new file mode 100644
index 0000000000..f063f85574
--- /dev/null
+++ b/activerecord/lib/active_record/associations/preloader/has_one_through.rb
@@ -0,0 +1,9 @@
+module ActiveRecord
+  module Associations
+    class Preloader
+      class HasOneThrough < SingularAssociation #:nodoc:
+        include ThroughAssociation
+      end
+    end
+  end
+end
diff --git a/activerecord/lib/active_record/associations/preloader/singular_association.rb b/activerecord/lib/active_record/associations/preloader/singular_association.rb
new file mode 100644
index 0000000000..44e804d785
--- /dev/null
+++ b/activerecord/lib/active_record/associations/preloader/singular_association.rb
@@ -0,0 +1,21 @@
+module ActiveRecord
+  module Associations
+    class Preloader
+      class SingularAssociation < Association #:nodoc:
+
+        private
+
+        def preload
+          associated_records_by_owner.each do |owner, associated_records|
+            record = associated_records.first
+
+            association = owner.association(reflection.name)
+            association.target = record
+            association.set_inverse_instance(record)
+          end
+        end
+
+      end
+    end
+  end
+end
diff --git a/activerecord/lib/active_record/associations/preloader/through_association.rb b/activerecord/lib/active_record/associations/preloader/through_association.rb
new file mode 100644
index 0000000000..ad6374d09a
--- /dev/null
+++ b/activerecord/lib/active_record/associations/preloader/through_association.rb
@@ -0,0 +1,67 @@
+module ActiveRecord
+  module Associations
+    class Preloader
+      module ThroughAssociation #:nodoc:
+
+        def through_reflection
+          reflection.through_reflection
+        end
+
+        def source_reflection
+          reflection.source_reflection
+        end
+
+        def associated_records_by_owner
+          through_records = through_records_by_owner
+
+          ActiveRecord::Associations::Preloader.new(
+            through_records.values.flatten,
+            source_reflection.name, options
+          ).run
+
+          through_records.each do |owner, records|
+            records.map! { |r| r.send(source_reflection.name) }.flatten!
+            records.compact!
+          end
+        end
+
+        private
+
+        def through_records_by_owner
+          ActiveRecord::Associations::Preloader.new(
+            owners, through_reflection.name,
+            through_options
+          ).run
+
+          Hash[owners.map do |owner|
+            through_records = Array.wrap(owner.send(through_reflection.name))
+
+            # Dont cache the association - we would only be caching a subset
+            if reflection.options[:source_type] && through_reflection.collection?
+              owner.association(through_reflection.name).reset
+            end
+
+            [owner, through_records]
+          end]
+        end
+
+        def through_options
+          through_options = {}
+
+          if options[:source_type]
+            through_options[:conditions] = { reflection.foreign_type => options[:source_type] }
+          else
+            if options[:conditions]
+              through_options[:include]    = options[:include] || options[:source]
+              through_options[:conditions] = options[:conditions]
+            end
+
+            through_options[:order] = options[:order]
+          end
+
+          through_options
+        end
+      end
+    end
+  end
+end