scrub bytes when upgrading notebooks from v2

v2 stores png/jpeg as b64 ascii bytes

IPython/nbformat/v3/convert.py

@@ -1,90 +1,88 b''
-"""Code for converting notebooks to and from the v2 format.
+"""Code for converting notebooks to and from the v2 format."""
 
-Authors:
-
-* Brian Granger
-* Min RK
-* Jonathan Frederic
-"""
-
-#-----------------------------------------------------------------------------
-#  Copyright (C) 2008-2011  The IPython Development Team
-#
-#  Distributed under the terms of the BSD License.  The full license is in
-#  the file COPYING, distributed as part of this software.
-#-----------------------------------------------------------------------------
-
-#-----------------------------------------------------------------------------
-# Imports
-#-----------------------------------------------------------------------------
+# Copyright (c) IPython Development Team.
+# Distributed under the terms of the Modified BSD License.
 
 from .nbbase import (
     new_code_cell, new_text_cell, new_worksheet, new_notebook, new_output,
     nbformat, nbformat_minor
 )
 
 from IPython.nbformat import v2
 
-#-----------------------------------------------------------------------------
-# Code
-#-----------------------------------------------------------------------------
+def _unbytes(obj):
+    """There should be no bytes objects in a notebook
+
+    v2 stores png/jpeg as b64 ascii bytes
+    """
+    if isinstance(obj, dict):
+        for k,v in obj.items():
+            obj[k] = _unbytes(v)
+    elif isinstance(obj, list):
+        for i,v in enumerate(obj):
+            obj[i] = _unbytes(v)
+    elif isinstance(obj, bytes):
+        # only valid bytes are b64-encoded ascii
+        obj = obj.decode('ascii')
+    return obj
 
 def upgrade(nb, from_version=2, from_minor=0):
     """Convert a notebook to v3.
 
     Parameters
     ----------
     nb : NotebookNode
         The Python representation of the notebook to convert.
     from_version : int
         The original version of the notebook to convert.
     from_minor : int
         The original minor version of the notebook to convert (only relevant for v >= 3).
     """
     if from_version == 2:
         # Mark the original nbformat so consumers know it has been converted.
         nb.nbformat = nbformat
         nb.nbformat_minor = nbformat_minor
         
         nb.orig_nbformat = 2
+        nb = _unbytes(nb)
         return nb
     elif from_version == 3:
         if from_minor != nbformat_minor:
             nb.orig_nbformat_minor = from_minor
         nb.nbformat_minor = nbformat_minor
         return nb
     else:
         raise ValueError('Cannot convert a notebook directly from v%s to v3.  ' \
                 'Try using the IPython.nbformat.convert module.' % from_version)
  
 
 def heading_to_md(cell):
     """turn heading cell into corresponding markdown"""
     cell.cell_type = "markdown"
     level = cell.pop('level', 1)
     cell.source = '#'*level + ' ' + cell.source
  
  
 def raw_to_md(cell):
     """let raw passthrough as markdown"""
     cell.cell_type = "markdown"
  
 
 def downgrade(nb):
     """Convert a v3 notebook to v2.
 
     Parameters
     ----------
     nb : NotebookNode
         The Python representation of the notebook to convert.
     """
     if nb.nbformat != 3:
         return nb
     nb.nbformat = 2
     for ws in nb.worksheets:
         for cell in ws.cells:
             if cell.cell_type == 'heading':
                 heading_to_md(cell)
             elif cell.cell_type == 'raw':
                 raw_to_md(cell)
     return nb
  No newline at end of file