Restore pre/post_save_hook traits, add register_pre/post_save_hook()

docs/source/developers/savehooks.rst

@@ -16,9 +16,6 @@ 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

@@ -82,16 +82,25 @@ def _validate_post_save_hook(self, proposal):
             value = import_item(value)
         if not callable(value):
             raise TraitError("post_save_hook must be callable")
-        self._post_save_hooks.append(value)
         return value
 
+    def register_post_save_hook(self, hook):
+        if isinstance(hook, str):
+            hook = import_item(hook)
+        if not callable(hook):
+            raise RuntimeError("post_save_hook must be callable")
+        self._post_save_hooks.append(hook)
+
     def __init__(self, *args, **kwargs):
         super().__init__(*args, **kwargs)
         self._post_save_hooks = []
 
-    def run_post_save_hook(self, model, os_path):
-        """Run the post-save hook if defined, and log errors"""
-        for post_save_hook in self._post_save_hooks:
+    def run_post_save_hooks(self, model, os_path):
+        """Run the post-save hooks if any, and log errors"""
+        post_save_hooks = self._post_save_hooks
+        if self.post_save_hook:
+            post_save_hooks.append(self.post_save_hook)
+        for post_save_hook in post_save_hooks:
             try:
                 self.log.debug("Running post-save hook on %s", os_path)
                 post_save_hook(os_path=os_path, model=model, contents_manager=self)
@@ -461,7 +470,7 @@ def save(self, model, path=""):
         """Save the file model and return the model with no content."""
         path = path.strip("/")
 
-        self.run_pre_save_hook(model=model, path=path)
+        self.run_pre_save_hooks(model=model, path=path)
 
         if "type" not in model:
             raise web.HTTPError(400, "No file type provided")
@@ -501,7 +510,7 @@ def save(self, model, path=""):
         if validation_message:
             model["message"] = validation_message
 
-        self.run_post_save_hook(model=model, os_path=os_path)
+        self.run_post_save_hooks(model=model, os_path=os_path)
 
         return model
 
@@ -787,7 +796,7 @@ async def save(self, model, path=""):
 
         os_path = self._get_os_path(path)
         self.log.debug("Saving %s", os_path)
-        self.run_pre_save_hook(model=model, path=path)
+        self.run_pre_save_hooks(model=model, path=path)
 
         if "type" not in model:
             raise web.HTTPError(400, "No file type provided")
@@ -824,7 +833,7 @@ async def save(self, model, path=""):
         if validation_message:
             model["message"] = validation_message
 
-        self.run_post_save_hook(model=model, os_path=os_path)
+        self.run_post_save_hooks(model=model, os_path=os_path)
 
         return model
 

jupyter_server/services/contents/largefilemanager.py

@@ -18,7 +18,7 @@ def save(self, model, path=""):
         if chunk is not None:
             path = path.strip("/")
 
-            self.run_pre_save_hook(model=model, path=path)
+            self.run_pre_save_hooks(model=model, path=path)
 
             if "type" not in model:
                 raise web.HTTPError(400, "No file type provided")
@@ -52,7 +52,7 @@ def save(self, model, path=""):
 
             # Last chunk
             if chunk == -1:
-                self.run_post_save_hook(model=model, os_path=os_path)
+                self.run_post_save_hooks(model=model, os_path=os_path)
             return model
         else:
             return super(LargeFileManager, self).save(model, path)
@@ -91,7 +91,7 @@ async def save(self, model, path=""):
 
             os_path = self._get_os_path(path)
             self.log.debug("Saving %s", os_path)
-            self.run_pre_save_hook(model=model, path=path)
+            self.run_pre_save_hooks(model=model, path=path)
 
             if "type" not in model:
                 raise web.HTTPError(400, "No file type provided")
@@ -122,7 +122,7 @@ async def save(self, model, path=""):
 
             # Last chunk
             if chunk == -1:
-                self.run_post_save_hook(model=model, os_path=os_path)
+                self.run_post_save_hooks(model=model, os_path=os_path)
             return model
         else:
             return await super(AsyncLargeFileManager, self).save(model, path)

jupyter_server/services/contents/manager.py

@@ -126,16 +126,25 @@ def _validate_pre_save_hook(self, proposal):
             value = import_item(self.pre_save_hook)
         if not callable(value):
             raise TraitError("pre_save_hook must be callable")
-        self._pre_save_hooks.append(value)
         return value
 
+    def register_pre_save_hook(self, hook):
+        if isinstance(hook, str):
+            hook = import_item(hook)
+        if not callable(hook):
+            raise RuntimeError("pre_save_hook must be callable")
+        self._pre_save_hooks.append(hook)
+
     def __init__(self, *args, **kwargs):
         super().__init__(*args, **kwargs)
         self._pre_save_hooks = []
 
-    def run_pre_save_hook(self, model, path, **kwargs):
-        """Run the pre-save hook if defined, and log errors"""
-        for pre_save_hook in self._pre_save_hooks:
+    def run_pre_save_hooks(self, model, path, **kwargs):
+        """Run the pre-save hooks if defined, and log errors"""
+        pre_save_hooks = self._pre_save_hooks
+        if self.pre_save_hook:
+            pre_save_hooks.append(self.pre_save_hook)
+        for pre_save_hook in pre_save_hooks:
             try:
                 self.log.debug("Running pre-save hook on %s", path)
                 pre_save_hook(model=model, path=path, contents_manager=self, **kwargs)