ruby on rails - Default value polymorphic associations doesn't work? -

ruby on rails - Default value polymorphic associations doesn't work? -

i have modified version of prototypical polymorphic model

class image < activerecord::base belongs_to :imageable, polymorphic: true before_save :default_value private def default_value rails.logger.debug("*** setting default value ***") # set default values here end end class employee < activerecord::base has_many :pictures, as: :imageable end class product < activerecord::base has_many :pictures, as: :imageable end

here i've tried set default values picture model, suggested in reply similar question.

problem is, default_value method isn't called when employee or product beingness saved.

i can confirm db set correctly, because ran in rails console:

emp = employee.create() # creating employee.id == 1 emp.pictures.count # == 0 picture.create(imageable_id: 1, imageable_type: "employee") # here, setting defaults works fine employee.find(1).pictures.count # == 1

so question is: why doesn't default_value called when save employee or product?

callbacks work same way console or server. callback triggered if object beingness saved.

if save employee alter value of kid on save, if attribute changed in child. example:

emp = employee.first emp.pictures.first.foo = "bar" # assuming have column foo in pictures table emp.save # save image , trigger callback `before_save`

but if have next scenario, pictures not saved:

emp = employee.first emp.save # save emp

if need save pictures reason, can following:

class employee < activerecord::base has_many :pictures, as: :imageable before_save :default_value def default_value self.pictures.update_all(foo: "bar") end end

ruby-on-rails ruby-on-rails-4 default-value polymorphic-associations