Question

Given the code (in routes.rb):

  resources :products do
    member do
      get :delete #this works
      delete delete: "products#destroy" #this doesn't work
      delete "delete" => "products#destroy" #but this works
    end
  end

Why the line delete delete: "products#destroy" doesn’t work and the line delete "delete" => "products#destroy" works?

Rails version 3.2.11

Answer 1

The reason why this doesn’t work and if you follow the error backtrace is because of the following line in the mapper.rb in Rails.

def match(path, *rest)
  if rest.empty? && Hash === path
    options  = path
    path, to = options.find { |name, value| name.is_a?(String) }
    options[:to] = to
    options.delete(path)
    paths = [path]
  else
    options = rest.pop || {}
     paths = [path] + rest
  end

  options[:anchor] = true unless options.key?(:anchor)

  if options[:on] && !VALID_ON_OPTIONS.include?(options[:on])
    raise ArgumentError, "Unknown scope #{on.inspect} given to :on"
  end
  paths.each { |_path| decomposed_match(_path, options.dup) }
  self
end

This is called by all the methods behind the scenes (e.g delete, post, get, put). The line that we are specifically looking for is the one that goes like this:

path, to = options.find { |name, value| name.is_a?(String) }

Not sure why they are checking against a String but since the name is a symbol and not a String but a Symbol. That pretty much sends that path as a nil value into decomposed_match causing somewhere down the line the reason why you cannot use a symbol in the routes.

NOTE

resources :products do
  member do
    get :delete #this works
    delete delete: "products#destroy" #this doesn't work
    delete "delete" => "products#destroy" #but this works
  end
end

The reason why get :delete works is because of the line before the match method is called.

Specifically under this method

def map_method(method, *args, &block)
  options = args.extract_options!
  options[:via] = method
  args.push(options)
  match(*args, &block)
  self
end

the line args.extract_options! removes a hash out of the array. You can find this under the file extract_options.rb which is an added method to the class Array.

Anyhow, since get :delete is not a hash but a single parameter it gets mapped to something like this

Path: [delete]
Options [{via: "get"}]

Now, the other ones get mapped like this take for example delete delete: "product#destroy"

Path {:delete=>"collaborators#destroy", via: "delete"}
Options []

Then it goes back to my original statement as to why Symbols don’t work in the routes.