DEV: Validate models returned from ContentsManager methods.

IPython/html/services/contents/handlers.py

@@ -25,6 +25,46 def sort_key(model):
     }.get(model['type'], '9')
     return u'%s%s' % (type_key, iname)
 
+
+def validate_model(model, expect_content):
+    required_keys = {
+        "name"
+        , "path"
+        , "type"
+        , "writable"
+        , "created"
+        # Note: This key is specified as just 'modified' in IPEP-27
+        , "last_modified"
+        , "mimetype"
+        , "content"
+        , "format"
+    }
+    missing = required_keys - set(model.keys())
+    if missing:
+        raise web.HTTPError(
+            500,
+            u"Missing Model Keys: {missing}".format(missing=missing),
+        )
+
+    # Note: Per IPEP-27, 'mimetype' should be present in this list.
+    maybe_none_keys = ['content', 'format']
+    if expect_content:
+        errors = [key for key in maybe_none_keys if model[key] is None]
+        if errors:
+            raise web.HTTPError(
+                500,
+                u"Keys unexpectedly None: {keys}".format(keys=errors),
+            )
+
+    else:
+        errors = [key for key in maybe_none_keys if model[key] is not None]
+        if errors:
+            raise web.HTTPError(
+                500,
+                u"Keys unexpectedly not None: {keys}".format(keys=errors),
+            )
+
+
 class ContentsHandler(IPythonHandler):
 
     SUPPORTED_METHODS = (u'GET', u'PUT', u'PATCH', u'POST', u'DELETE')
@@ -72,6 +112,7 class ContentsHandler(IPythonHandler):
             # 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)
         self._finish_model(model, location=False)
 
     @web.authenticated
@@ -83,6 +124,7 class ContentsHandler(IPythonHandler):
         if model is None:
             raise web.HTTPError(400, u'JSON body missing')
         model = cm.update(model, path)
+        validate_model(model, expect_content=False)
         self._finish_model(model)
 
     def _copy(self, copy_from, copy_to=None):
@@ -93,6 +135,7 class ContentsHandler(IPythonHandler):
         ))
         model = self.contents_manager.copy(copy_from, copy_to)
         self.set_status(201)
+        validate_model(model, expect_content=False)
         self._finish_model(model)
 
     def _upload(self, model, path):
@@ -100,6 +143,7 class ContentsHandler(IPythonHandler):
         self.log.info(u"Uploading file to %s", path)
         model = self.contents_manager.new(model, path)
         self.set_status(201)
+        validate_model(model, expect_content=False)
         self._finish_model(model)
         
     def _new_untitled(self, path, type='', ext=''):
@@ -107,12 +151,14 class ContentsHandler(IPythonHandler):
         self.log.info(u"Creating new %s in %s", type or 'file', path)
         model = self.contents_manager.new_untitled(path=path, type=type, ext=ext)
         self.set_status(201)
+        validate_model(model, expect_content=False)
         self._finish_model(model)
 
     def _save(self, model, path):
         """Save an existing file."""
         self.log.info(u"Saving file at %s", path)
         model = self.contents_manager.save(model, path)
+        validate_model(model, expect_content=False)
         self._finish_model(model)
 
     @web.authenticated