Question

I have this simple case statement :

  class_name = case link_path
    when current_page?(jobs_path)               then 'current'
    when current_page?(open_estimates_path)     then 'current'
    when current_page?(tasks_path)              then 'current'
    when current_page?(calendar_dispatch_path)  then 'current'
  end
  debugger

At my break point, I can ask, current_page?(tasks_path), and it will return true.

Then I ask class_name, and it returns nil.

What syntactical error am I making here?

ruby 1.9.2p136

Rails 3.0.10

Answer 1

The case statement doesn’t do what you think it does. It compares the subject to all the values stated in the when branches and returns the value of the first matching one. For example:

color = case num_color
          when 1 then 'red'
          when 2 then 'green'
          when 3 then 'blue'
        end

You are giving it link_path as the subject, so it compares link_path to each of the booleans in your when branches. As link_path is probably not a boolean value, none of the branches will be evaluated. Maybe you want something like this instead:

class_name = current_page?(link_path) ? 'current' : ''

This will set class_name to "current" if link_path is the current page, otherwise to "".