Add .use to allow for custom middleware.

Author: Michael Bleigh

lib/grape/api.rb

@@ -177,7 +177,24 @@ def namespace(space = nil, &block)
       def scope(name = nil, &block)
         nest(block)
       end
-      
+
+      # Apply a custom middleware to the API. Applies
+      # to the current namespace and any children, but
+      # not parents.
+      #
+      # @param middleware_class [Class] The class of the middleware you'd like to inject.
+      def use(middleware_class, *args)
+        settings_stack.last[:middleware] ||= []
+        settings_stack.last[:middleware] << [middleware_class, *args]        
+      end
+
+      # Retrieve an array of the middleware classes
+      # and arguments that are currently applied to the
+      # application.
+      def middleware
+        settings_stack.inject([]){|a,s| a += s[:middleware] if s[:middleware]; a}
+      end
+
       protected
 
       # Execute first the provided block, then each of the
@@ -202,7 +219,8 @@ def build_endpoint(&block)
         b.use Grape::Middleware::Prefixer, :prefix => prefix if prefix        
         b.use Grape::Middleware::Versioner, :versions => (version if version.is_a?(Array)) if version
         b.use Grape::Middleware::Formatter, :default_format => default_format || :json
-        
+        middleware.each{|m| b.use *m }
+
         endpoint = Grape::Endpoint.generate(&block)
         endpoint.send :include, helpers
         b.run endpoint

spec/grape/api_spec.rb

@@ -227,6 +227,67 @@ def app; subject end
     end
   end
 
+  context 'custom middleware' do
+    class PhonyMiddleware
+      def initialize(app, *args)
+        @args = args
+        @app = app
+      end
+
+      def call(env)
+        env['phony.args'] ||= []
+        env['phony.args'] << @args
+        @app.call(env)
+      end
+    end
+
+    describe '.middleware' do
+      it 'should include middleware arguments from settings' do
+        subject.stub!(:settings_stack).and_return [{:middleware => [[PhonyMiddleware, 'abc', 123]]}]
+        subject.middleware.should == [[PhonyMiddleware, 'abc', 123]]
+      end
+
+      it 'should include all middleware from stacked settings' do
+        subject.stub!(:settings_stack).and_return [
+          {:middleware => [[PhonyMiddleware, 123],[PhonyMiddleware, 'abc']]},
+          {:middleware => [[PhonyMiddleware, 'foo']]}
+        ]
+  
+        subject.middleware.should == [
+          [PhonyMiddleware, 123],
+          [PhonyMiddleware, 'abc'],
+          [PhonyMiddleware, 'foo']
+        ]
+      end
+    end
+
+    describe '.use' do
+      it 'should add middleware' do
+        subject.use PhonyMiddleware, 123
+        subject.middleware.should == [[PhonyMiddleware, 123]]
+      end
+
+      it 'should not show up outside the namespace' do
+        subject.use PhonyMiddleware, 123
+        subject.namespace :awesome do
+          use PhonyMiddleware, 'abc'
+          middleware.should == [[PhonyMiddleware, 123],[PhonyMiddleware, 'abc']]
+        end
+
+        subject.middleware.should == [[PhonyMiddleware, 123]]        
+      end
+
+      it 'should actually call the middleware' do
+        subject.use PhonyMiddleware, 'hello'
+        subject.get '/' do
+          env['phony.args'].first.first
+        end
+
+        get '/'
+        last_response.body.should == 'hello'
+      end
+    end
+  end
   describe '.basic' do
     it 'should protect any resources on the same scope' do
       subject.http_basic do |u,p|