Add config.default_method_for_update to support PATCH

PATCH is the correct HTML verb to map to the #update action. The
semantics for PATCH allows for partial updates, whereas PUT requires a
complete replacement.

Changes:
* adds config.default_method_for_update you can set to :patch
* optionally use PATCH instead of PUT in resource routes and forms
* adds the #patch verb to routes to detect PATCH requests
* adds #patch? to Request
* changes documentation and comments to indicate support for PATCH

This change maintains complete backwards compatibility by keeping :put
as the default for config.default_method_for_update.

1 files changed, 11 insertions, 4 deletions

diff --git a/actionpack/test/dispatch/request_test.rb b/actionpack/test/dispatch/request_test.rb
index 8f0ac5310e..6c8b22c47f 100644
--- a/actionpack/test/dispatch/request_test.rb
+++ b/actionpack/test/dispatch/request_test.rb
@@ -325,14 +325,14 @@ class RequestTest < ActiveSupport::TestCase
   end
 
   test "String request methods" do
-    [:get, :post, :put, :delete].each do |method|
+    [:get, :post, :patch, :put, :delete].each do |method|
       request = stub_request 'REQUEST_METHOD' => method.to_s.upcase
       assert_equal method.to_s.upcase, request.method
     end
   end
 
   test "Symbol forms of request methods via method_symbol" do
-    [:get, :post, :put, :delete].each do |method|
+    [:get, :post, :patch, :put, :delete].each do |method|
       request = stub_request 'REQUEST_METHOD' => method.to_s.upcase
       assert_equal method, request.method_symbol
     end
@@ -346,7 +346,7 @@ class RequestTest < ActiveSupport::TestCase
   end
 
   test "allow method hacking on post" do
-    %w(GET OPTIONS PUT POST DELETE).each do |method|
+    %w(GET OPTIONS PATCH PUT POST DELETE).each do |method|
       request = stub_request "REQUEST_METHOD" => method.to_s.upcase
       assert_equal(method == "HEAD" ? "GET" : method, request.method)
     end
@@ -360,7 +360,7 @@ class RequestTest < ActiveSupport::TestCase
   end
 
   test "restrict method hacking" do
-    [:get, :put, :delete].each do |method|
+    [:get, :patch, :put, :delete].each do |method|
       request = stub_request 'REQUEST_METHOD' => method.to_s.upcase,
         'action_dispatch.request.request_parameters' => { :_method => 'put' }
       assert_equal method.to_s.upcase, request.method
@@ -375,6 +375,13 @@ class RequestTest < ActiveSupport::TestCase
     assert request.head?
   end
 
+  test "post masquerading as patch" do
+    request = stub_request 'REQUEST_METHOD' => 'PATCH', "rack.methodoverride.original_method" => "POST"
+    assert_equal "POST", request.method
+    assert_equal "PATCH",  request.request_method
+    assert request.patch?
+  end
+
   test "post masquerading as put" do
     request = stub_request 'REQUEST_METHOD' => 'PUT', "rack.methodoverride.original_method" => "POST"
     assert_equal "POST", request.method