Allow a defining custom member field on resources

By default, resources routes are created with :resource/:id. A model
defining to_param can make prettier urls by using something more
readable than an integer ID, but since the route picks it up as :id you
wind up with awkward User.find_by_username(params[:id]) calls.

By overriding the key to be used in @request.params you can be more
obvious in your intent.

1 files changed, 18 insertions, 0 deletions

diff --git a/actionpack/test/dispatch/routing_test.rb b/actionpack/test/dispatch/routing_test.rb
index 700666600b..cc4279d9dd 100644
--- a/actionpack/test/dispatch/routing_test.rb
+++ b/actionpack/test/dispatch/routing_test.rb
@@ -475,6 +475,11 @@ class TestRoutingMapper < ActionDispatch::IntegrationTest
         get :preview, :on => :member
       end
 
+      resources :profiles, :param => :username do
+        get :details, :on => :member
+        resources :messages
+      end
+
       scope :as => "routes" do
         get "/c/:id", :as => :collision, :to => "collision#show"
         get "/collision", :to => "collision#show"
@@ -2183,6 +2188,19 @@ class TestRoutingMapper < ActionDispatch::IntegrationTest
     assert_equal "/posts/1/admin", post_admin_root_path(:post_id => '1')
   end
 
+  def test_custom_param
+    get '/profiles/bob'
+    assert_equal 'profiles#show', @response.body
+    assert_equal 'bob', @request.params[:username]
+
+    get '/profiles/bob/details'
+    assert_equal 'bob', @request.params[:username]
+
+    get '/profiles/bob/messages/34'
+    assert_equal 'bob', @request.params[:profile_username]
+    assert_equal '34', @request.params[:id]
+  end
+
 private
   def with_https
     old_https = https?