Monkeypatch IPythonHandler to find nbclassic's jinja templates

nbclassic/nbserver.py

@@ -133,22 +133,17 @@ def sorted_extensions(self):
                 )
                 manager.link_extension(name)
 
-    # Monkey-patch Jupyter Server's template and static path list to include
-    # the classic notebooks template folder. Since there are some
-    # redundancy in the template names between these two packages,
-    # this patch makes an opinionated choice to use the templates
-    # in the classic notebook first. This should be a *safe* choice
-    # because the Jupyter Server templates are simpler, more
-    # stripped down versions of the classic notebook templates. If
-    # the templates in Jupyter server eventually change, we may
-    # need to revisit this patch.
-    def template_file_path(self):
-        """return extra paths + the default locations"""
-        return self.extra_template_paths + \
-            notebook.DEFAULT_TEMPLATE_PATH_LIST + \
-            jupyter_server.DEFAULT_TEMPLATE_PATH_LIST
-
-    serverapp.__class__.template_file_path = property(template_file_path)
+    # Monkeypatch the IPython handler to pull templates from the "correct"
+    # Jinja Environment, namespaced by "notebook".
+    def get_template(self, name):
+        """Return the jinja template object for a given name"""
+        return self.settings['notebook_jinja2_env'].get_template(name)
+
+    notebook.base.handlers.IPythonHandler.get_template = get_template
+
+
+    # Monkey-patch Jupyter Server's and nbclassic's static path list to include
+    # the classic notebooks static folder.
 
     def static_file_path_jupyter_server(self):
         """return extra paths + the default location"""

nbclassic/notebookapp.py

@@ -248,33 +248,42 @@ def initialize_handlers(self):
         # need to tbe injected into the wildcard routes.
         static_handlers = []
 
+        base_url = self.serverapp.base_url
+        ujoin = url_path_join
         # Add terminal handlers
         static_handlers.append(
-            (r"/terminals/(\w+)", TerminalHandler)
+            (ujoin(base_url, r"/terminals/(\w+)"), TerminalHandler)
         )
         static_handlers.append(
             # (r"/nbextensions/(?!nbextensions_configurator\/list)(.*)", FileFindHandler, {
-            (r"/nbextensions/(.*)", FileFindHandler, {
+            (ujoin(base_url, r"/nbextensions/(.*)"), FileFindHandler, {
                 'path': self.settings['nbextensions_path'],
                 # don't cache anything in nbextensions
                 'no_cache_paths': ['/'],
             }),
         )
         static_handlers.append(
-            (r"/custom/(.*)", FileFindHandler, {
+            (ujoin(base_url, r"/custom/(.*)"), FileFindHandler, {
                 'path': self.settings['static_custom_path'],
                 # don't cache anything in nbextensions
                 'no_cache_paths': ['/'],
             }),
         )
-        # Get the wildcard router
+        # Add these static handlers after the Notebook base handlers
+        # to match the original order of handlers in the classic
+        # notebook codebase.
+        base_handlers = load_handlers('jupyter_server.base.handlers')
+        # The extra two handlers (+2) cover the redirect handler
+        # and the final 404 handler.
+        n = len(base_handlers) + 2
+        # Inject the handlers in the tornado router.
         router = self.serverapp.web_app.wildcard_router
-        # Pop out the last route... this route is the final "catch-all" 404.
-        last_route = router.rules.pop(-1)
-        # Add the handlers above
+        core_rules = router.rules[:-n]
+        final_rules = router.rules[-n:]
+        router.rules = []
+        router.add_rules(core_rules)
         router.add_rules(static_handlers)
-        # Put the 404 handlers back at the end.
-        router.rules.append(last_route)
+        router.add_rules(final_rules)
 
 # -----------------------------------------------------------------------------
 # Main entry point

nbclassic/tests/test_nbserver.py

@@ -7,7 +7,7 @@ def test_classic_notebook_templates(jp_serverapp):
         "tree.html"
     ]
     # Get the server's template environment.
-    template_env = jp_serverapp.web_app.settings.get("jinja2_env")
+    template_env = jp_serverapp.web_app.settings.get("notebook_jinja2_env")
 
     for name in classic_notebook_templates:
         template_env.get_template(name)