Question

The [column_name]_changed? in the controller is not work, but in the model is ok?

original_name = "test1"
new_name = "test2"

@user = User.find(params[:id])
puts"__________#{@user.name}" # "test1"
@user.update_attributes(params[:user])
puts"__________#{@user.name}" # "test2"
@user.name_changed? # return false is't not work

Answer 1

From the fine manual:

update_attributes(attributes, options = {})

Updates the attributes of the model from the passed-in hash and saves the record, all wrapped in a transaction.

Note the saves the record part. So after your update_attributes call succeeds, all the new values have been written to the database and nothing will be left in the changed state; hence, all the x_changed? methods will return false.

If you want something that is like update_attributes but doesn’t do the save, then you ca use assign_attributes or attributes= instead:

@user.assign_attributes(params[:user])
# or @user.attributes = params[:user]
#...
@user.save # You have to do this by hand

The update_attributes method is just this:

with_transaction_returning_status do
  self.assign_attributes(attributes, options)
  save
end

after all.