Update documentation

docs/source/developers/savehooks.rst

@@ -16,6 +16,9 @@ They are both called with keyword arguments::
     pre_save_hook(model=model, path=path, contents_manager=cm)
     post_save_hook(model=model, os_path=os_path, contents_manager=cm)
 
+Assigning to ``pre_save_hook`` (or ``post_save_hook``) multiple times will
+register hooks, not override them. They will then be called sequentially.
+
 Examples
 --------
 

jupyter_server/services/contents/filemanager.py

@@ -96,7 +96,12 @@ def run_post_save_hook(self, model, os_path):
                 self.log.debug("Running post-save hook on %s", os_path)
                 post_save_hook(os_path=os_path, model=model, contents_manager=self)
             except Exception as e:
-                self.log.error("Post-save %s hook failed on %s", post_save_hook.__name__, os_path, exc_info=True)
+                self.log.error(
+                    "Post-save %s hook failed on %s",
+                    post_save_hook.__name__,
+                    os_path,
+                    exc_info=True,
+                )
                 raise web.HTTPError(
                     500, "Unexpected error while running post hook save: %s" % e
                 ) from e
@@ -294,7 +299,9 @@ def _dir_model(self, path, content=True):
         if not os.path.isdir(os_path):
             raise web.HTTPError(404, four_o_four)
         elif is_hidden(os_path, self.root_dir) and not self.allow_hidden:
-            self.log.info("Refusing to serve hidden directory %r, via 404 Error", os_path)
+            self.log.info(
+                "Refusing to serve hidden directory %r, via 404 Error", os_path
+            )
             raise web.HTTPError(404, four_o_four)
 
         model = self._base_model(path)
@@ -316,7 +323,9 @@ def _dir_model(self, path, content=True):
                     # skip over broken symlinks in listing
                     if e.errno == errno.ENOENT:
                         self.log.warning("%s doesn't exist", os_path)
-                    elif e.errno != errno.EACCES:  # Don't provide clues about protected files
+                    elif (
+                        e.errno != errno.EACCES
+                    ):  # Don't provide clues about protected files
                         self.log.warning("Error stat-ing %s: %s", os_path, e)
                     continue
 
@@ -330,8 +339,12 @@ def _dir_model(self, path, content=True):
 
                 try:
                     if self.should_list(name):
-                        if self.allow_hidden or not is_file_hidden(os_path, stat_res=st):
-                            contents.append(self.get(path="%s/%s" % (path, name), content=False))
+                        if self.allow_hidden or not is_file_hidden(
+                            os_path, stat_res=st
+                        ):
+                            contents.append(
+                                self.get(path="%s/%s" % (path, name), content=False)
+                            )
                 except OSError as e:
                     # ELOOP: recursive symlink, also don't show failure due to permissions
                     if e.errno not in [errno.ELOOP, errno.EACCES]:
@@ -530,7 +543,11 @@ def is_non_empty_dir(os_path):
             return False
 
         if self.delete_to_trash:
-            if not self.always_delete_dir and sys.platform == "win32" and is_non_empty_dir(os_path):
+            if (
+                not self.always_delete_dir
+                and sys.platform == "win32"
+                and is_non_empty_dir(os_path)
+            ):
                 # send2trash can really delete files on Windows, so disallow
                 # deleting non-empty files. See Github issue 3631.
                 raise web.HTTPError(400, "Directory %s not empty" % os_path)
@@ -598,7 +615,9 @@ def get_kernel_path(self, path, model=None):
         return parent_dir
 
 
-class AsyncFileContentsManager(FileContentsManager, AsyncFileManagerMixin, AsyncContentsManager):
+class AsyncFileContentsManager(
+    FileContentsManager, AsyncFileManagerMixin, AsyncContentsManager
+):
     @default("checkpoints_class")
     def _checkpoints_class_default(self):
         return AsyncFileCheckpoints
@@ -615,7 +634,9 @@ async def _dir_model(self, path, content=True):
         if not os.path.isdir(os_path):
             raise web.HTTPError(404, four_o_four)
         elif is_hidden(os_path, self.root_dir) and not self.allow_hidden:
-            self.log.info("Refusing to serve hidden directory %r, via 404 Error", os_path)
+            self.log.info(
+                "Refusing to serve hidden directory %r, via 404 Error", os_path
+            )
             raise web.HTTPError(404, four_o_four)
 
         model = self._base_model(path)
@@ -638,7 +659,9 @@ async def _dir_model(self, path, content=True):
                     # skip over broken symlinks in listing
                     if e.errno == errno.ENOENT:
                         self.log.warning("%s doesn't exist", os_path)
-                    elif e.errno != errno.EACCES:  # Don't provide clues about protected files
+                    elif (
+                        e.errno != errno.EACCES
+                    ):  # Don't provide clues about protected files
                         self.log.warning("Error stat-ing %s: %s", os_path, e)
                     continue
 
@@ -652,9 +675,13 @@ async def _dir_model(self, path, content=True):
 
                 try:
                     if self.should_list(name):
-                        if self.allow_hidden or not is_file_hidden(os_path, stat_res=st):
+                        if self.allow_hidden or not is_file_hidden(
+                            os_path, stat_res=st
+                        ):
                             contents.append(
-                                await self.get(path="%s/%s" % (path, name), content=False)
+                                await self.get(
+                                    path="%s/%s" % (path, name), content=False
+                                )
                             )
                 except OSError as e:
                     # ELOOP: recursive symlink, also don't show failure due to permissions

jupyter_server/services/contents/manager.py

@@ -146,7 +146,12 @@ def run_pre_save_hook(self, model, path, **kwargs):
             except Exception:
                 # unhandled errors don't prevent saving,
                 # which could cause frustrating data loss
-                self.log.error("Pre-save hook %s failed on %s", pre_save_hook.__name__, path, exc_info=True)
+                self.log.error(
+                    "Pre-save hook %s failed on %s",
+                    pre_save_hook.__name__,
+                    path,
+                    exc_info=True,
+                )
 
     checkpoints_class = Type(Checkpoints, config=True)
     checkpoints = Instance(Checkpoints, config=True)
@@ -196,7 +201,9 @@ def get_extra_handlers(self):
         """
         handlers = []
         if self.files_handler_class:
-            handlers.append((r"/files/(.*)", self.files_handler_class, self.files_handler_params))
+            handlers.append(
+                (r"/files/(.*)", self.files_handler_class, self.files_handler_params)
+            )
         return handlers
 
     # ContentsManager API part 1: methods that must be