`--script` triggers post_save hook with nbconvert

IPython/html/services/contents/filemanager.py

@@ -1,659 +1,690 b''
 """A contents manager that uses the local file system for storage."""
 
 # Copyright (c) IPython Development Team.
 # Distributed under the terms of the Modified BSD License.
 
 import base64
 import errno
 import io
 import os
 import shutil
 from contextlib import contextmanager
 import mimetypes
 
 from tornado import web
 
 from .manager import ContentsManager
 from IPython import nbformat
 from IPython.utils.io import atomic_writing
 from IPython.utils.importstring import import_item
 from IPython.utils.path import ensure_dir_exists
 from IPython.utils.traitlets import Any, Unicode, Bool, TraitError
 from IPython.utils.py3compat import getcwd, str_to_unicode
 from IPython.utils import tz
 from IPython.html.utils import is_hidden, to_os_path, to_api_path
 
+_script_exporter = None
+def _post_save_script(model, os_path, contents_manager, **kwargs):
+    """convert notebooks to Python script after save with nbconvert
+
+    replaces `ipython notebook --script`
+    """
+    from IPython.nbconvert.exporters.python import PythonExporter
+
+    if model['type'] != 'notebook':
+        return
+    global _script_exporter
+    if _script_exporter is None:
+        _script_exporter = PythonExporter(parent=contents_manager)
+    log = contents_manager.log
+
+    base, ext = os.path.splitext(os_path)
+    py_fname = base + '.py'
+    log.info("Writing %s", py_fname)
+    py, resources = _script_exporter.from_filename(os_path)
+    with io.open(py_fname, 'w', encoding='utf-8') as f:
+        f.write(py)
 
 class FileContentsManager(ContentsManager):
 
     root_dir = Unicode(config=True)
 
     def _root_dir_default(self):
         try:
             return self.parent.notebook_dir
         except AttributeError:
             return getcwd()
     
     @contextmanager
     def perm_to_403(self, os_path=''):
         """context manager for turning permission errors into 403"""
         try:
             yield
         except OSError as e:
             if e.errno in {errno.EPERM, errno.EACCES}:
                 # make 403 error message without root prefix
                 # this may not work perfectly on unicode paths on Python 2,
                 # but nobody should be doing that anyway.
                 if not os_path:
                     os_path = str_to_unicode(e.filename or 'unknown file')
                 path = to_api_path(os_path, self.root_dir)
                 raise web.HTTPError(403, u'Permission denied: %s' % path)
             else:
                 raise
     
     @contextmanager
     def open(self, os_path, *args, **kwargs):
         """wrapper around io.open that turns permission errors into 403"""
         with self.perm_to_403(os_path):
             with io.open(os_path, *args, **kwargs) as f:
                 yield f
     
     @contextmanager
     def atomic_writing(self, os_path, *args, **kwargs):
         """wrapper around atomic_writing that turns permission errors into 403"""
         with self.perm_to_403(os_path):
             with atomic_writing(os_path, *args, **kwargs) as f:
                 yield f
     
-    save_script = Bool(False, config=True, help='DEPRECATED, IGNORED')
+    save_script = Bool(False, config=True, help='DEPRECATED, use post_save_hook')
     def _save_script_changed(self):
         self.log.warn("""
-        Automatically saving notebooks as scripts has been removed.
-        Use `ipython nbconvert --to python [notebook]` instead.
+        `--script` is deprecated. You can trigger nbconvert via pre- or post-save hooks:
+
+            ContentsManager.pre_save_hook
+            FileContentsManager.post_save_hook
+
+        A post-save hook has been registered that calls:
+
+            ipython nbconvert --to python [notebook]
+
+        which behaves similar to `--script`.
         """)
 
+        self.post_save_hook = _post_save_script
+
     post_save_hook = Any(None, config=True,
         help="""Python callable or importstring thereof
 
         to be called on the path of a file just saved.
 
         This can be used to
         This can be used to process the file on disk,
         such as converting the notebook to other formats, such as Python or HTML via nbconvert
 
         It will be called as (all arguments passed by keyword):
 
             hook(os_path=os_path, model=model, contents_manager=instance)
 
         path: the filesystem path to the file just written
         model: the model representing the file
         contents_manager: this ContentsManager instance
         """
     )
     def _post_save_hook_changed(self, name, old, new):
         if new and isinstance(new, string_types):
             self.post_save_hook = import_item(self.post_save_hook)
         elif new:
             if not callable(new):
                 raise TraitError("post_save_hook must be callable")
 
     def run_post_save_hook(self, model, os_path):
         """Run the post-save hook if defined, and log errors"""
         if self.post_save_hook:
             try:
                 self.log.debug("Running post-save hook on %s", os_path)
                 self.post_save_hook(os_path=os_path, model=model, contents_manager=self)
             except Exception:
                 self.log.error("Post-save hook failed on %s", os_path, exc_info=True)
 
     def _root_dir_changed(self, name, old, new):
         """Do a bit of validation of the root_dir."""
         if not os.path.isabs(new):
             # If we receive a non-absolute path, make it absolute.
             self.root_dir = os.path.abspath(new)
             return
         if not os.path.isdir(new):
             raise TraitError("%r is not a directory" % new)
 
     checkpoint_dir = Unicode('.ipynb_checkpoints', config=True,
         help="""The directory name in which to keep file checkpoints
 
         This is a path relative to the file's own directory.
 
         By default, it is .ipynb_checkpoints
         """
     )
 
     def _copy(self, src, dest):
         """copy src to dest
 
         like shutil.copy2, but log errors in copystat
         """
         shutil.copyfile(src, dest)
         try:
             shutil.copystat(src, dest)
         except OSError as e:
             self.log.debug("copystat on %s failed", dest, exc_info=True)
 
     def _get_os_path(self, path):
         """Given an API path, return its file system path.
 
         Parameters
         ----------
         path : string
             The relative API path to the named file.
 
         Returns
         -------
         path : string
             Native, absolute OS path to for a file.
         """
         return to_os_path(path, self.root_dir)
 
     def dir_exists(self, path):
         """Does the API-style path refer to an extant directory?
 
         API-style wrapper for os.path.isdir
 
         Parameters
         ----------
         path : string
             The path to check. This is an API path (`/` separated,
             relative to root_dir).
 
         Returns
         -------
         exists : bool
             Whether the path is indeed a directory.
         """
         path = path.strip('/')
         os_path = self._get_os_path(path=path)
         return os.path.isdir(os_path)
 
     def is_hidden(self, path):
         """Does the API style path correspond to a hidden directory or file?
 
         Parameters
         ----------
         path : string
             The path to check. This is an API path (`/` separated,
             relative to root_dir).
 
         Returns
         -------
         hidden : bool
             Whether the path exists and is hidden.
         """
         path = path.strip('/')
         os_path = self._get_os_path(path=path)
         return is_hidden(os_path, self.root_dir)
 
     def file_exists(self, path):
         """Returns True if the file exists, else returns False.
 
         API-style wrapper for os.path.isfile
 
         Parameters
         ----------
         path : string
             The relative path to the file (with '/' as separator)
 
         Returns
         -------
         exists : bool
             Whether the file exists.
         """
         path = path.strip('/')
         os_path = self._get_os_path(path)
         return os.path.isfile(os_path)
 
     def exists(self, path):
         """Returns True if the path exists, else returns False.
 
         API-style wrapper for os.path.exists
 
         Parameters
         ----------
         path : string
             The API path to the file (with '/' as separator)
 
         Returns
         -------
         exists : bool
             Whether the target exists.
         """
         path = path.strip('/')
         os_path = self._get_os_path(path=path)
         return os.path.exists(os_path)
 
     def _base_model(self, path):
         """Build the common base of a contents model"""
         os_path = self._get_os_path(path)
         info = os.stat(os_path)
         last_modified = tz.utcfromtimestamp(info.st_mtime)
         created = tz.utcfromtimestamp(info.st_ctime)
         # Create the base model.
         model = {}
         model['name'] = path.rsplit('/', 1)[-1]
         model['path'] = path
         model['last_modified'] = last_modified
         model['created'] = created
         model['content'] = None
         model['format'] = None
         model['mimetype'] = None
         try:
             model['writable'] = os.access(os_path, os.W_OK)
         except OSError:
             self.log.error("Failed to check write permissions on %s", os_path)
             model['writable'] = False
         return model
 
     def _dir_model(self, path, content=True):
         """Build a model for a directory
 
         if content is requested, will include a listing of the directory
         """
         os_path = self._get_os_path(path)
 
         four_o_four = u'directory does not exist: %r' % path
 
         if not os.path.isdir(os_path):
             raise web.HTTPError(404, four_o_four)
         elif is_hidden(os_path, self.root_dir):
             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)
         model['type'] = 'directory'
         if content:
             model['content'] = contents = []
             os_dir = self._get_os_path(path)
             for name in os.listdir(os_dir):
                 os_path = os.path.join(os_dir, name)
                 # skip over broken symlinks in listing
                 if not os.path.exists(os_path):
                     self.log.warn("%s doesn't exist", os_path)
                     continue
                 elif not os.path.isfile(os_path) and not os.path.isdir(os_path):
                     self.log.debug("%s not a regular file", os_path)
                     continue
                 if self.should_list(name) and not is_hidden(os_path, self.root_dir):
                     contents.append(self.get(
                         path='%s/%s' % (path, name),
                         content=False)
                     )
 
             model['format'] = 'json'
 
         return model
 
     def _file_model(self, path, content=True, format=None):
         """Build a model for a file
 
         if content is requested, include the file contents.
 
         format:
           If 'text', the contents will be decoded as UTF-8.
           If 'base64', the raw bytes contents will be encoded as base64.
           If not specified, try to decode as UTF-8, and fall back to base64
         """
         model = self._base_model(path)
         model['type'] = 'file'
 
         os_path = self._get_os_path(path)
         model['mimetype'] = mimetypes.guess_type(os_path)[0] or 'text/plain'
 
         if content:
             if not os.path.isfile(os_path):
                 # could be FIFO
                 raise web.HTTPError(400, "Cannot get content of non-file %s" % os_path)
             with self.open(os_path, 'rb') as f:
                 bcontent = f.read()
 
             if format != 'base64':
                 try:
                     model['content'] = bcontent.decode('utf8')
                 except UnicodeError as e:
                     if format == 'text':
                         raise web.HTTPError(400, "%s is not UTF-8 encoded" % path)
                 else:
                     model['format'] = 'text'
 
             if model['content'] is None:
                 model['content'] = base64.encodestring(bcontent).decode('ascii')
                 model['format'] = 'base64'
 
         return model
 
 
     def _notebook_model(self, path, content=True):
         """Build a notebook model
 
         if content is requested, the notebook content will be populated
         as a JSON structure (not double-serialized)
         """
         model = self._base_model(path)
         model['type'] = 'notebook'
         if content:
             os_path = self._get_os_path(path)
             with self.open(os_path, 'r', encoding='utf-8') as f:
                 try:
                     nb = nbformat.read(f, as_version=4)
                 except Exception as e:
                     raise web.HTTPError(400, u"Unreadable Notebook: %s %r" % (os_path, e))
             self.mark_trusted_cells(nb, path)
             model['content'] = nb
             model['format'] = 'json'
             self.validate_notebook_model(model)
         return model
 
     def get(self, path, content=True, type_=None, format=None):
         """ Takes a path for an entity and returns its model
 
         Parameters
         ----------
         path : str
             the API path that describes the relative path for the target
         content : bool
             Whether to include the contents in the reply
         type_ : str, optional
             The requested type - 'file', 'notebook', or 'directory'.
             Will raise HTTPError 400 if the content doesn't match.
         format : str, optional
             The requested format for file contents. 'text' or 'base64'.
             Ignored if this returns a notebook or directory model.
 
         Returns
         -------
         model : dict
             the contents model. If content=True, returns the contents
             of the file or directory as well.
         """
         path = path.strip('/')
 
         if not self.exists(path):
             raise web.HTTPError(404, u'No such file or directory: %s' % path)
 
         os_path = self._get_os_path(path)
         if os.path.isdir(os_path):
             if type_ not in (None, 'directory'):
                 raise web.HTTPError(400,
                                 u'%s is a directory, not a %s' % (path, type_))
             model = self._dir_model(path, content=content)
         elif type_ == 'notebook' or (type_ is None and path.endswith('.ipynb')):
             model = self._notebook_model(path, content=content)
         else:
             if type_ == 'directory':
                 raise web.HTTPError(400,
                                 u'%s is not a directory')
             model = self._file_model(path, content=content, format=format)
         return model
 
     def _save_notebook(self, os_path, model, path=''):
         """save a notebook file"""
         # Save the notebook file
         nb = nbformat.from_dict(model['content'])
 
         self.check_and_sign(nb, path)
 
         with self.atomic_writing(os_path, encoding='utf-8') as f:
             nbformat.write(nb, f, version=nbformat.NO_CONVERT)
 
     def _save_file(self, os_path, model, path=''):
         """save a non-notebook file"""
         fmt = model.get('format', None)
         if fmt not in {'text', 'base64'}:
             raise web.HTTPError(400, "Must specify format of file contents as 'text' or 'base64'")
         try:
             content = model['content']
             if fmt == 'text':
                 bcontent = content.encode('utf8')
             else:
                 b64_bytes = content.encode('ascii')
                 bcontent = base64.decodestring(b64_bytes)
         except Exception as e:
             raise web.HTTPError(400, u'Encoding error saving %s: %s' % (os_path, e))
         with self.atomic_writing(os_path, text=False) as f:
             f.write(bcontent)
 
     def _save_directory(self, os_path, model, path=''):
         """create a directory"""
         if is_hidden(os_path, self.root_dir):
             raise web.HTTPError(400, u'Cannot create hidden directory %r' % os_path)
         if not os.path.exists(os_path):
             with self.perm_to_403():
                 os.mkdir(os_path)
         elif not os.path.isdir(os_path):
             raise web.HTTPError(400, u'Not a directory: %s' % (os_path))
         else:
             self.log.debug("Directory %r already exists", os_path)
 
     def save(self, model, path=''):
         """Save the file model and return the model with no content."""
         path = path.strip('/')
 
         if 'type' not in model:
             raise web.HTTPError(400, u'No file type provided')
         if 'content' not in model and model['type'] != 'directory':
             raise web.HTTPError(400, u'No file content provided')
 
         self.run_pre_save_hook(model=model, path=path)
 
         # One checkpoint should always exist
         if self.file_exists(path) and not self.list_checkpoints(path):
             self.create_checkpoint(path)
 
         os_path = self._get_os_path(path)
         self.log.debug("Saving %s", os_path)
         try:
             if model['type'] == 'notebook':
                 self._save_notebook(os_path, model, path)
             elif model['type'] == 'file':
                 self._save_file(os_path, model, path)
             elif model['type'] == 'directory':
                 self._save_directory(os_path, model, path)
             else:
                 raise web.HTTPError(400, "Unhandled contents type: %s" % model['type'])
         except web.HTTPError:
             raise
         except Exception as e:
             self.log.error(u'Error while saving file: %s %s', path, e, exc_info=True)
             raise web.HTTPError(500, u'Unexpected error while saving file: %s %s' % (path, e))
 
         validation_message = None
         if model['type'] == 'notebook':
             self.validate_notebook_model(model)
             validation_message = model.get('message', None)
 
         model = self.get(path, content=False)
         if validation_message:
             model['message'] = validation_message
 
         self.run_post_save_hook(model=model, os_path=os_path)
 
         return model
 
     def update(self, model, path):
         """Update the file's path
 
         For use in PATCH requests, to enable renaming a file without
         re-uploading its contents. Only used for renaming at the moment.
         """
         path = path.strip('/')
         new_path = model.get('path', path).strip('/')
         if path != new_path:
             self.rename(path, new_path)
         model = self.get(new_path, content=False)
         return model
 
     def delete(self, path):
         """Delete file at path."""
         path = path.strip('/')
         os_path = self._get_os_path(path)
         rm = os.unlink
         if os.path.isdir(os_path):
             listing = os.listdir(os_path)
             # don't delete non-empty directories (checkpoints dir doesn't count)
             if listing and listing != [self.checkpoint_dir]:
                 raise web.HTTPError(400, u'Directory %s not empty' % os_path)
         elif not os.path.isfile(os_path):
             raise web.HTTPError(404, u'File does not exist: %s' % os_path)
 
         # clear checkpoints
         for checkpoint in self.list_checkpoints(path):
             checkpoint_id = checkpoint['id']
             cp_path = self.get_checkpoint_path(checkpoint_id, path)
             if os.path.isfile(cp_path):
                 self.log.debug("Unlinking checkpoint %s", cp_path)
                 with self.perm_to_403():
                     rm(cp_path)
 
         if os.path.isdir(os_path):
             self.log.debug("Removing directory %s", os_path)
             with self.perm_to_403():
                 shutil.rmtree(os_path)
         else:
             self.log.debug("Unlinking file %s", os_path)
             with self.perm_to_403():
                 rm(os_path)
 
     def rename(self, old_path, new_path):
         """Rename a file."""
         old_path = old_path.strip('/')
         new_path = new_path.strip('/')
         if new_path == old_path:
             return
 
         new_os_path = self._get_os_path(new_path)
         old_os_path = self._get_os_path(old_path)
 
         # Should we proceed with the move?
         if os.path.exists(new_os_path):
             raise web.HTTPError(409, u'File already exists: %s' % new_path)
 
         # Move the file
         try:
             with self.perm_to_403():
                 shutil.move(old_os_path, new_os_path)
         except web.HTTPError:
             raise
         except Exception as e:
             raise web.HTTPError(500, u'Unknown error renaming file: %s %s' % (old_path, e))
 
         # Move the checkpoints
         old_checkpoints = self.list_checkpoints(old_path)
         for cp in old_checkpoints:
             checkpoint_id = cp['id']
             old_cp_path = self.get_checkpoint_path(checkpoint_id, old_path)
             new_cp_path = self.get_checkpoint_path(checkpoint_id, new_path)
             if os.path.isfile(old_cp_path):
                 self.log.debug("Renaming checkpoint %s -> %s", old_cp_path, new_cp_path)
                 with self.perm_to_403():
                     shutil.move(old_cp_path, new_cp_path)
 
     # Checkpoint-related utilities
 
     def get_checkpoint_path(self, checkpoint_id, path):
         """find the path to a checkpoint"""
         path = path.strip('/')
         parent, name = ('/' + path).rsplit('/', 1)
         parent = parent.strip('/')
         basename, ext = os.path.splitext(name)
         filename = u"{name}-{checkpoint_id}{ext}".format(
             name=basename,
             checkpoint_id=checkpoint_id,
             ext=ext,
         )
         os_path = self._get_os_path(path=parent)
         cp_dir = os.path.join(os_path, self.checkpoint_dir)
         with self.perm_to_403():
             ensure_dir_exists(cp_dir)
         cp_path = os.path.join(cp_dir, filename)
         return cp_path
 
     def get_checkpoint_model(self, checkpoint_id, path):
         """construct the info dict for a given checkpoint"""
         path = path.strip('/')
         cp_path = self.get_checkpoint_path(checkpoint_id, path)
         stats = os.stat(cp_path)
         last_modified = tz.utcfromtimestamp(stats.st_mtime)
         info = dict(
             id = checkpoint_id,
             last_modified = last_modified,
         )
         return info
 
     # public checkpoint API
 
     def create_checkpoint(self, path):
         """Create a checkpoint from the current state of a file"""
         path = path.strip('/')
         if not self.file_exists(path):
             raise web.HTTPError(404)
         src_path = self._get_os_path(path)
         # only the one checkpoint ID:
         checkpoint_id = u"checkpoint"
         cp_path = self.get_checkpoint_path(checkpoint_id, path)
         self.log.debug("creating checkpoint for %s", path)
         with self.perm_to_403():
             self._copy(src_path, cp_path)
 
         # return the checkpoint info
         return self.get_checkpoint_model(checkpoint_id, path)
 
     def list_checkpoints(self, path):
         """list the checkpoints for a given file
 
         This contents manager currently only supports one checkpoint per file.
         """
         path = path.strip('/')
         checkpoint_id = "checkpoint"
         os_path = self.get_checkpoint_path(checkpoint_id, path)
         if not os.path.exists(os_path):
             return []
         else:
             return [self.get_checkpoint_model(checkpoint_id, path)]
 
 
     def restore_checkpoint(self, checkpoint_id, path):
         """restore a file to a checkpointed state"""
         path = path.strip('/')
         self.log.info("restoring %s from checkpoint %s", path, checkpoint_id)
         nb_path = self._get_os_path(path)
         cp_path = self.get_checkpoint_path(checkpoint_id, path)
         if not os.path.isfile(cp_path):
             self.log.debug("checkpoint file does not exist: %s", cp_path)
             raise web.HTTPError(404,
                 u'checkpoint does not exist: %s@%s' % (path, checkpoint_id)
             )
         # ensure notebook is readable (never restore from an unreadable notebook)
         if cp_path.endswith('.ipynb'):
             with self.open(cp_path, 'r', encoding='utf-8') as f:
                 nbformat.read(f, as_version=4)
         self.log.debug("copying %s -> %s", cp_path, nb_path)
         with self.perm_to_403():
             self._copy(cp_path, nb_path)
 
     def delete_checkpoint(self, checkpoint_id, path):
         """delete a file's checkpoint"""
         path = path.strip('/')
         cp_path = self.get_checkpoint_path(checkpoint_id, path)
         if not os.path.isfile(cp_path):
             raise web.HTTPError(404,
                 u'Checkpoint does not exist: %s@%s' % (path, checkpoint_id)
             )
         self.log.debug("unlinking %s", cp_path)
         os.unlink(cp_path)
 
     def info_string(self):
         return "Serving notebooks from local directory: %s" % self.root_dir
 
     def get_kernel_path(self, path, model=None):
         """Return the initial API path of  a kernel associated with a given notebook"""
         if '/' in path:
             parent_dir = path.rsplit('/', 1)[0]
         else:
             parent_dir = ''
         return parent_dir