Checking for nil value using :before_save

Question

In my view I have a dropdown of people within an organisation that a ticket can be assigned to.

<label for="assigned_support_id">Assigned To</label>
<%= select( "ticket", "assigned_support_id", Person.find_admin_and_support.collect {|p| ["#{p.name}", p.id]}, {:include_blank => "&lt; Unassigned &gt;"} ) %>

Because the blank inserted above has no value, if that option is selected then the ticket will remain assigned to the same person.

I've considered creating an 'Unassigned' person in the database but that will probably be quite complicated having that 'person' belong to every organisation....

I also considered using JavaScript to manipulate the DOM and give it a value but I wanted to do this the 'Rails Way' so I've come up with the following:

ticket.rb

before_save :check_unassigned

...

private

def check_unassigned
  if self.assigned_support_id.nil? or defined?(self.assigned_support_id)
    self.assigned_support_id = 0
  end
end

The nil check didn't seem to do anything so I added the defined check but the problem with that is that every time I reassign a ticket to another user it the table will be updated with 0 so something isn't quite right and I'm not sure what the bug is.

I also considered updating the update method in my controller by checking the [:params][:assigned_support_id] but thought the above was a neater solution.

Answer 1

If salf.assigned_support_id exists then it's true under 'defined?'...

so any code where you have

if (some_irrelevant_evaluation) or defined?(self.assigned_support_id) 

is ALWAYS going to evaluate to true.