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, 3 insertions, 3 deletions

diff --git a/activemodel/lib/active_model/lint.rb b/activemodel/lib/active_model/lint.rb
index 49ea894150..a10fdefd1a 100644
--- a/activemodel/lib/active_model/lint.rb
+++ b/activemodel/lib/active_model/lint.rb
@@ -62,9 +62,9 @@ module ActiveModel
       #
       # Returns a boolean that specifies whether the object has been persisted yet.
       # This is used when calculating the URL for an object. If the object is
-      # not persisted, a form for that object, for instance, will be POSTed to the
-      # collection. If it is persisted, a form for the object will be PUT to the
-      # URL for the object.
+      # not persisted, a form for that object, for instance, will route to the
+      # create action. If it is persisted, a form for the object will routes to
+      # the update action.
       def test_persisted?
         assert model.respond_to?(:persisted?), "The model should respond to persisted?"
         assert_boolean model.persisted?, "persisted?"