select base JupyterHandler according to application implementation

Author: minrk

nbgitpuller/__init__.py

@@ -1,5 +1,4 @@
 from .version import __version__ # noqa
-from .handlers import SyncHandler, UIHandler, LegacyInteractRedirectHandler, LegacyGitSyncRedirectHandler
 from .pull import GitPuller # noqa
 from jupyter_server.utils import url_path_join
 from tornado.web import StaticFileHandler
@@ -33,6 +32,19 @@ def _load_jupyter_server_extension(app):
     - notebook: https://jupyter-notebook.readthedocs.io/en/stable/examples/Notebook/Distributing%20Jupyter%20Extensions%20as%20Python%20Packages.html#Example---Server-extension
     - jupyter_server: https://jupyter-server.readthedocs.io/en/latest/developers/extensions.html
     """
+    # identify base handler by app class
+    # must do this before importing from .handlers
+    from ._compat import get_base_handler
+
+    get_base_handler(app)
+
+    from .handlers import (
+        SyncHandler,
+        UIHandler,
+        LegacyInteractRedirectHandler,
+        LegacyGitSyncRedirectHandler,
+    )
+
     web_app = app.web_app
     base_url = url_path_join(web_app.settings['base_url'], 'git-pull')
     handlers = [

nbgitpuller/_compat.py

@@ -0,0 +1,40 @@
+"""Import base Handler classes from Jupyter Server or Notebook
+
+Must be called before importing .handlers to ensure the correct base classes
+"""
+import warnings
+
+_JupyterHandler = None
+
+
+def get_base_handler(app=None):
+    """Get the base JupyterHandler class to use
+
+    Inferred from app class (either jupyter_server or notebook app)
+    """
+    global _JupyterHandler
+    if _JupyterHandler is not None:
+        return _JupyterHandler
+    if app is None:
+        warnings.warn(
+            "Guessing base JupyterHandler class. Specify an app to ensure the right JupyterHandler is used.",
+            stacklevel=2,
+        )
+        from jupyter_server.base.handlers import JupyterHandler
+        return JupyterHandler
+
+    top_modules = {cls.__module__.split(".", 1)[0] for cls in app.__class__.mro()}
+    if "jupyter_server" in top_modules:
+        from jupyter_server.base.handlers import JupyterHandler
+
+        _JupyterHandler = JupyterHandler
+        return _JupyterHandler
+    if "notebook" in top_modules:
+        from notebook.base.handlers import IPythonHandler
+
+        _JupyterHandler = IPythonHandler
+        return _JupyterHandler
+
+    warnings.warn(f"Failed to detect base JupyterHandler class for {app}.", stacklevel=2)
+    from jupyter_server.base.handlers import JupyterHandler
+    return JupyterHandler

nbgitpuller/handlers.py

@@ -2,7 +2,6 @@
 import traceback
 import urllib.parse
 
-from jupyter_server.base.handlers import JupyterHandler
 import threading
 import json
 import os
@@ -11,6 +10,9 @@
 
 from .pull import GitPuller
 from .version import __version__
+from ._compat import get_base_handler
+
+JupyterHandler = get_base_handler()
 
 
 jinja_env = jinja2.Environment(loader=jinja2.FileSystemLoader(