Merge pull request #13279 from misfo/session-fetch-that-behaves-like-hash-fetch

Make ActionDispatch::Request::Session#fetch behave like Hash#fetch

3 files changed, 11 insertions, 14 deletions

diff --git a/actionpack/CHANGELOG.md b/actionpack/CHANGELOG.md
index 3d507392b1..199f8e1ec3 100644
--- a/actionpack/CHANGELOG.md
+++ b/actionpack/CHANGELOG.md
@@ -85,9 +85,7 @@
 
 *   Add `session#fetch` method
 
-    fetch behaves similarly to [Hash#fetch](http://www.ruby-doc.org/core-1.9.3/Hash.html#method-i-fetch),
-    with the exception that the returned value is always saved into the session.
-
+    fetch behaves like [Hash#fetch](http://www.ruby-doc.org/core-1.9.3/Hash.html#method-i-fetch).  
     It returns a value from the hash for the given key.
     If the key can’t be found, there are several options:
 
diff --git a/actionpack/lib/action_dispatch/request/session.rb b/actionpack/lib/action_dispatch/request/session.rb
index 6d911a75f1..973627f106 100644
--- a/actionpack/lib/action_dispatch/request/session.rb
+++ b/actionpack/lib/action_dispatch/request/session.rb
@@ -7,6 +7,9 @@ module ActionDispatch
       ENV_SESSION_KEY         = Rack::Session::Abstract::ENV_SESSION_KEY # :nodoc:
       ENV_SESSION_OPTIONS_KEY = Rack::Session::Abstract::ENV_SESSION_OPTIONS_KEY # :nodoc:
 
+      # Singleton object used to determine if an optional param wasn't specified
+      Unspecified = Object.new
+
       def self.create(store, env, default_options)
         session_was = find env
         session     = Request::Session.new(store, env)
@@ -127,15 +130,12 @@ module ActionDispatch
         @delegate.delete key.to_s
       end
 
-      def fetch(key, default=nil)
-        if self.key?(key)
-          self[key]
-        elsif default
-          self[key] = default
-        elsif block_given?
-          self[key] = yield(key)
+      def fetch(key, default=Unspecified, &block)
+        load_for_read!
+        if default == Unspecified
+          @delegate.fetch(key.to_s, &block)
         else
-          raise KeyError
+          @delegate.fetch(key.to_s, default, &block)
         end
       end
 
diff --git a/actionpack/test/dispatch/request/session_test.rb b/actionpack/test/dispatch/request/session_test.rb
index a244d1364c..df55fcc8bc 100644
--- a/actionpack/test/dispatch/request/session_test.rb
+++ b/actionpack/test/dispatch/request/session_test.rb
@@ -68,13 +68,12 @@ module ActionDispatch
         assert_equal '1', session.fetch(:one)
 
         assert_equal '2', session.fetch(:two, '2')
-        assert_equal '2', session.fetch(:two)
+        assert_nil session.fetch(:two, nil)
 
         assert_equal 'three', session.fetch(:three) {|el| el.to_s }
-        assert_equal 'three', session.fetch(:three)
 
         assert_raise KeyError do
-          session.fetch(:four)
+          session.fetch(:three)
         end
       end