Support for create_association! for has_one associations

2 files changed, 5 insertions, 1 deletions

diff --git a/activerecord/lib/active_record/associations.rb b/activerecord/lib/active_record/associations.rb
index 2e0f54e505..a03d1bbb06 100644
--- a/activerecord/lib/active_record/associations.rb
+++ b/activerecord/lib/active_record/associations.rb
@@ -1536,6 +1536,7 @@ module ActiveRecord
             "build_#{reflection.name}"  => "build",
             "create_#{reflection.name}" => "create"
           }
+          constructors["create_#{reflection.name}!"] = "create!" if reflection.macro == :has_one
 
           constructors.each do |name, proxy_name|
             redefine_method(name) do |*params|
diff --git a/activerecord/lib/active_record/associations/has_one_association.rb b/activerecord/lib/active_record/associations/has_one_association.rb
index f60547c22c..c29ab8dcec 100644
--- a/activerecord/lib/active_record/associations/has_one_association.rb
+++ b/activerecord/lib/active_record/associations/has_one_association.rb
@@ -7,7 +7,7 @@ module ActiveRecord
       end
 
       def create!(attributes = {})
-        new_record(:create_association!, attributes)
+        build(attributes).tap { |record| record.save! }
       end
 
       def build(attributes = {})
@@ -51,6 +51,9 @@ module ActiveRecord
 
         alias creation_attributes construct_owner_attributes
 
+        # The reason that the save param for replace is false, if for create (not just build),
+        # is because the setting of the foreign keys is actually handled by the scoping, and
+        # so they are set straight away and do not need to be updated within replace.
         def new_record(method, attributes)
           record = scoped.scoping { @reflection.send(method, attributes) }
           replace(record, false)