Question

I have a route that looks like

match 'solar_systems/:planet_num/:moon_num' => 'solar_system#moon', :as => :moon

I’d like to have a form with a select box for planet number and moon number and have it submit to this route. However I cannot use moon_path because it will have an error if the dynamic parameters are not included in it like this moon_path(4, 1). Is what I want even possible? If so, what do I give to the form tag for the route?

Answer 1

You don’t have to use the routing helper methods, and here you can’t since at the time of rendering your form you do not know the required parameters. You do, however, know the controller and action, which is really all that’s needed for the destination URL. So this should work:

= form_tag('/solar_systems/moon') do
  = select_tag(:planet_num, ...
  = select_tag(:moon_num, ...

This should render the form tag. To process the request, you will also have to add another route so the right controller action is called:

match 'solar_systems#moon' => 'solar_system#moon', :via => :post

Or, if it makes more sense in the context of your application, you could modify your existing route to make the parameters optional:

match 'solar_systems(/:planet_num(/:moon_num')) => 'solar_system#moon', :as => :moon

See this Rails guide for more details on non-resourceful routes.