Allow building and then later saving has_many :through records, such that the join record is automatically saved too. This requires the :inverse_of option to be set on the source association in the join model. See the CHANGELOG for details. [#4329 state:resolved]

1 files changed, 46 insertions, 4 deletions

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 9f74d57c4d..c4d3ef8fef 100644
--- a/activerecord/lib/active_record/associations/has_many_through_association.rb
+++ b/activerecord/lib/active_record/associations/has_many_through_association.rb
@@ -37,16 +37,44 @@ module ActiveRecord
 
         def insert_record(record, validate = true)
           return if record.new_record? && !record.save(:validate => validate)
-
-          through_association = @owner.send(@reflection.through_reflection.name)
-          through_association.create!(construct_join_attributes(record))
-
+          through_record(record).save!
           update_counter(1)
           record
         end
 
       private
 
+        def through_record(record)
+          through_association = @owner.send(:association_proxy, @reflection.through_reflection.name)
+          attributes = construct_join_attributes(record)
+
+          through_record = Array.wrap(through_association.target).find { |candidate|
+            candidate.attributes.slice(*attributes.keys) == attributes
+          }
+
+          unless through_record
+            through_record = through_association.build(attributes)
+            through_record.send("#{@reflection.source_reflection.name}=", record)
+          end
+
+          through_record
+        end
+
+        def build_record(attributes)
+          record = super(attributes)
+
+          inverse = @reflection.source_reflection.inverse_of
+          if inverse
+            if inverse.macro == :has_many
+              record.send(inverse.name) << through_record(record)
+            elsif inverse.macro == :has_one
+              record.send("#{inverse.name}=", through_record(record))
+            end
+          end
+
+          record
+        end
+
         def target_reflection_has_associated_record?
           if @reflection.through_reflection.macro == :belongs_to && @owner[@reflection.through_reflection.foreign_key].blank?
             false
@@ -79,6 +107,8 @@ module ActiveRecord
             count = scope.delete_all
           end
 
+          delete_through_records(through, records)
+
           if @reflection.through_reflection.macro == :has_many && update_through_counter?(method)
             update_counter(-count, @reflection.through_reflection)
           end
@@ -86,6 +116,18 @@ module ActiveRecord
           update_counter(-count)
         end
 
+        def delete_through_records(through, records)
+          if @reflection.through_reflection.macro == :has_many
+            records.each do |record|
+              through.target.delete(through_record(record))
+            end
+          else
+            records.each do |record|
+              through.target = nil if through.target == through_record(record)
+            end
+          end
+        end
+
         def find_target
           return [] unless target_reflection_has_associated_record?
           scoped.all