adding values to a select box from a controller function (Ruby on Rails)

Question

I have a Rails web application with a select box:

<%= select_tag :foo %>

I'm looking to write a function in the controller which would populate this select box with some values. What code would I need to write in order to do that?

It's fine if the values are hard coded into the function.

def populate
  # what goes here?
end

Answer 1

Take a look at options_for_select. It builds the html for what you want to display.

  options_for_select([["Dollar", "$"], ["Kroner", "DKK"]])
    <option value="$">Dollar</option>\n<option value="DKK">Kroner</option>

  options_for_select([ "VISA", "MasterCard" ], "MasterCard")
    <option>VISA</option>\n<option selected="selected">MasterCard</option>

  options_for_select({ "Basic" => "$20", "Plus" => "$40" }, "$40")
    <option value="$20">Basic</option>\n<option value="$40" selected="selected">Plus</option>

  options_for_select([ "VISA", "MasterCard", "Discover" ], ["VISA", "Discover"])
    <option selected="selected">VISA</option>\n<option>MasterCard</option>\n<option selected="selected">Discover</option>

You can just pass the result of this function to select_tag like so:

  <%= select_tag 'company_id', options_for_select(@current_user.active_companies.map { |c| [c.name, c.id] }) %>

Answer 2

Doing things like populating a select are best done in a helper. If your controller is named MyController then you can have a MyHelper module in the helpers directory. Methods, etc. inside the helper will be available inside your view templates. So, you could have a populate_select method in your MyHelper and do everything there that you are wanting to do in your controller. That's more "the Rails way." Helpers are intended to handle the heavy Ruby code that your templates need so you don't have to mix it with your XHTML.