New config option additional_metadata_on_text_files #110

HISTORY.rst

@@ -9,7 +9,7 @@ Release History
 **Improvements**
 
 - Notebook metadata is filtered - only the most common metadata are stored in the text representation (#105)
-- Notebooks created from light and sphinx scripts do not have YAML header or cell metadata if there was none initially (#110)
+- New config option `additional_metadata_on_text_files` on the content manager. Defaults to `True`. Change its value to `False` to avoid creating a YAML header or cell metadata if there was none initially (#110)
 - First markdown cell exported as a docstring when using the Sphinx format (#107)
 
 0.8.3 (2018-10-19)

jupytext/contentsmanager.py

@@ -29,9 +29,11 @@ def _writes(nbk, version=nbformat.NO_CONVERT, **kwargs):
     return _writes
 
 
-def _jupytext_reads(ext, format_name, rst2md):
+def _jupytext_reads(ext, format_name, rst2md, additional_metadata_on_text_files):
     def _reads(text, as_version, **kwargs):
-        return jupytext.reads(text, ext=ext, format_name=format_name, rst2md=rst2md, as_version=as_version, **kwargs)
+        return jupytext.reads(text, ext=ext, format_name=format_name, rst2md=rst2md,
+                              additional_metadata_on_text_files=additional_metadata_on_text_files,
+                              as_version=as_version, **kwargs)
 
     return _reads
 
@@ -148,6 +150,13 @@ def all_nb_extensions(self):
              "Examples: 'all', 'hide_input,hide_output'",
         config=True)
 
+    additional_metadata_on_text_files = Bool(
+        True,
+        help='Allow (or not) additional notebook and cell metadata to be saved to a text file '
+             'that has no "jupyter" section or no YAML header.',
+        config=True
+    )
+
     comment_magics = Enum(
         values=[True, False],
         allow_none=True,
@@ -228,7 +237,9 @@ def _read_notebook(self, os_path, as_version=4):
         _, fmt, ext = file_fmt_ext(os_path)
         if ext in self.nb_extensions:
             format_name = self.preferred_format(fmt, self.preferred_jupytext_formats_read)
-            with mock.patch('nbformat.reads', _jupytext_reads(fmt, format_name, self.sphinx_convert_rst2md)):
+            with mock.patch('nbformat.reads', _jupytext_reads(fmt, format_name,
+                                                              self.sphinx_convert_rst2md,
+                                                              self.additional_metadata_on_text_files)):
                 return super(TextFileContentsManager, self)._read_notebook(os_path, as_version)
         else:
             return super(TextFileContentsManager, self)._read_notebook(os_path, as_version)
@@ -251,8 +262,7 @@ def _save_notebook(self, os_path, nb):
                 format_name = format_name_for_ext(nb.metadata, alt_fmt, self.default_jupytext_formats,
                                                   explicit_default=False) or \
                               self.preferred_format(alt_fmt, self.preferred_jupytext_formats_save)
-                with mock.patch('nbformat.writes',
-                                _jupytext_writes(alt_fmt, format_name)):
+                with mock.patch('nbformat.writes', _jupytext_writes(alt_fmt, format_name)):
                     super(TextFileContentsManager, self)._save_notebook(os_path_fmt, nb)
             else:
                 super(TextFileContentsManager, self)._save_notebook(os_path_fmt, nb)

jupytext/jupytext.py

@@ -26,9 +26,10 @@
 class TextNotebookReader(NotebookReader):
     """Text notebook reader"""
 
-    def __init__(self, ext, format_name=None):
+    def __init__(self, ext, format_name=None, additional_metadata_on_text_files=True):
         self.ext = ext
         self.format = get_format(ext, format_name)
+        self.additional_metadata_on_text_files = additional_metadata_on_text_files
 
     def reads(self, s, **_):
         """Read a notebook from text"""
@@ -57,7 +58,7 @@ def reads(self, s, **_):
                 raise Exception('Blocked at lines ' + '\n'.join(lines[:6]))
             lines = lines[pos:]
 
-        if not metadata and self.format.format_name in ['markdown', 'light', 'sphinx', 'sphinx-rst2md']:
+        if not self.additional_metadata_on_text_files and not metadata:
             metadata['jupytext'] = {'metadata_filter': {'notebook': False}}
             if not cell_metadata:
                 metadata['jupytext']['metadata_filter']['cells'] = False
@@ -138,7 +139,7 @@ def writes(self, nb, **kwargs):
 
 
 def reads(text, ext, format_name=None,
-          rst2md=False, as_version=4, **kwargs):
+          rst2md=False, additional_metadata_on_text_files=True, as_version=4, **kwargs):
     """Read a notebook from a string"""
     if ext.endswith('.ipynb'):
         return nbformat.reads(text, as_version, **kwargs)
@@ -150,7 +151,7 @@ def reads(text, ext, format_name=None,
         if format_name == 'sphinx' and rst2md:
             format_name = 'sphinx-rst2md'
 
-    reader = TextNotebookReader(ext, format_name)
+    reader = TextNotebookReader(ext, format_name, additional_metadata_on_text_files)
     notebook = reader.reads(text, **kwargs)
     transition_to_jupytext_section_in_metadata(notebook.metadata, False)
 

tests/test_header.py

@@ -94,7 +94,7 @@ def test_metadata_and_cell_to_header2():
 def test_notebook_from_plain_script_has_metadata_filter(script="""print('Hello world")
 """):
     with mock.patch('jupytext.header.INSERT_AND_CHECK_VERSION_NUMBER', True):
-        nb = jupytext.reads(script, '.py')
+        nb = jupytext.reads(script, '.py', additional_metadata_on_text_files=False)
     assert nb.metadata.get('jupytext', {}).get('metadata_filter', {}).get('notebook') is False
     assert nb.metadata.get('jupytext', {}).get('metadata_filter', {}).get('cells') is False
     with mock.patch('jupytext.header.INSERT_AND_CHECK_VERSION_NUMBER', True):