allow requesting contents without body

adds `?content=0` to only fetch the metadata in the model.

The REST API now exposes all arguments to ContentsManager.get.

IPython/html/services/contents/handlers.py

@@ -117,13 +117,19 b' class ContentsHandler(IPythonHandler):'
         format = self.get_query_argument('format', default=None)
         if format not in {None, 'text', 'base64'}:
             raise web.HTTPError(400, u'Format %r is invalid' % format)
-
-        model = yield gen.maybe_future(self.contents_manager.get(path=path, type=type, format=format))
-        if model['type'] == 'directory':
+        content = self.get_query_argument('content', default='1')
+        if content not in {'0', '1'}:
+            raise web.HTTPError(400, u'Content %r is invalid' % content)
+        content = int(content)
+        
+        model = yield gen.maybe_future(self.contents_manager.get(
+            path=path, type=type, format=format, content=content,
+        ))
+        if model['type'] == 'directory' and content:
             # group listing by type, then by name (case-insensitive)
             # FIXME: sorting should be done in the frontends
             model['content'].sort(key=sort_key)
-        validate_model(model, expect_content=True)
+        validate_model(model, expect_content=content)
         self._finish_model(model, location=False)
 
     @web.authenticated

IPython/html/services/contents/tests/test_contents_api.py

@@ -51,12 +51,14 b' class API(object):'
     def list(self, path='/'):
         return self._req('GET', path)
 
-    def read(self, path, type=None, format=None):
+    def read(self, path, type=None, format=None, content=None):
         params = {}
         if type is not None:
             params['type'] = type
         if format is not None:
             params['format'] = format
+        if content == False:
+            params['content'] = '0'
         return self._req('GET', path, params=params)
 
     def create_untitled(self, path='/', ext='.ipynb'):
@@ -243,6 +245,14 b' class APITest(NotebookTestBase):'
         dir_names = {normalize('NFC', d['name']) for d in dirs}
         self.assertEqual(dir_names, self.top_level_dirs)  # Excluding hidden dirs
 
+    def test_get_dir_no_content(self):
+        for d in self.dirs:
+            model = self.api.read(d, content=False).json()
+            self.assertEqual(model['path'], d)
+            self.assertEqual(model['type'], 'directory')
+            self.assertIn('content', model)
+            self.assertEqual(model['content'], None)
+
     def test_list_nonexistant_dir(self):
         with assert_http_error(404):
             self.api.list('nonexistant')
@@ -256,10 +266,19 b' class APITest(NotebookTestBase):'
             self.assertEqual(nb['type'], 'notebook')
             self.assertIn('content', nb)
             self.assertEqual(nb['format'], 'json')
-            self.assertIn('content', nb)
             self.assertIn('metadata', nb['content'])
             self.assertIsInstance(nb['content']['metadata'], dict)
 
+    def test_get_nb_no_content(self):
+        for d, name in self.dirs_nbs:
+            path = url_path_join(d, name + '.ipynb')
+            nb = self.api.read(path, content=False).json()
+            self.assertEqual(nb['name'], u'%s.ipynb' % name)
+            self.assertEqual(nb['path'], path)
+            self.assertEqual(nb['type'], 'notebook')
+            self.assertIn('content', nb)
+            self.assertEqual(nb['content'], None)
+
     def test_get_contents_no_such_file(self):
         # Name that doesn't exist - should be a 404
         with assert_http_error(404):

IPython/html/static/services/contents.js

@@ -72,13 +72,12 b' define(function(require) {'
     /**
      * Get a file.
      *
-     * Calls success with file JSON model, or error with error.
-     *
      * @method get
      * @param {String} path
      * @param {Object} options
      *    type : 'notebook', 'file', or 'directory'
      *    format: 'text' or 'base64'; only relevant for type: 'file'
+     *    content: true or false; // whether to include the content
      */
     Contents.prototype.get = function (path, options) {
         /**
@@ -94,6 +93,7 b' define(function(require) {'
         var params = {};
         if (options.type) { params.type = options.type; }
         if (options.format) { params.format = options.format; }
+        if (options.content === false) { params.content = '0'; }
         return utils.promising_ajax(url + '?' + $.param(params), settings);
     };