Not need to pass join attributes to association build

2 files changed, 10 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 9657cb081d..53d49fef2e 100644
--- a/activerecord/lib/active_record/associations/has_many_through_association.rb
+++ b/activerecord/lib/active_record/associations/has_many_through_association.rb
@@ -73,7 +73,9 @@ module ActiveRecord
         # association
         def build_through_record(record)
           @through_records[record.object_id] ||= begin
-            through_record = through_association.build(construct_join_attributes(record))
+            ensure_mutable
+
+            through_record = through_association.build
             through_record.send("#{source_reflection.name}=", record)
             through_record
           end
diff --git a/activerecord/lib/active_record/associations/through_association.rb b/activerecord/lib/active_record/associations/through_association.rb
index f95e5337c2..fd0e90aaf0 100644
--- a/activerecord/lib/active_record/associations/through_association.rb
+++ b/activerecord/lib/active_record/associations/through_association.rb
@@ -37,9 +37,7 @@ module ActiveRecord
         # situation it is more natural for the user to just create or modify their join records
         # directly as required.
         def construct_join_attributes(*records)
-          if source_reflection.macro != :belongs_to
-            raise HasManyThroughCantAssociateThroughHasOneOrManyReflection.new(owner, reflection)
-          end
+          ensure_mutable
 
           join_attributes = {
             source_reflection.foreign_key =>
@@ -73,6 +71,12 @@ module ActiveRecord
           !owner[through_reflection.foreign_key].nil?
         end
 
+        def ensure_mutable
+          if source_reflection.macro != :belongs_to
+            raise HasManyThroughCantAssociateThroughHasOneOrManyReflection.new(owner, reflection)
+          end
+        end
+
         def ensure_not_nested
           if reflection.nested?
             raise HasManyThroughNestedAssociationsAreReadonly.new(owner, reflection)