Fixing attribute access.

IPython/nbconvert/filters/citation.py

@@ -1,72 +1,72 b''
 """Citation handling for LaTeX output."""
 
 #-----------------------------------------------------------------------------
 # Copyright (c) 2013, the IPython Development Team.
 #
 # Distributed under the terms of the Modified BSD License.
 #
 # The full license is in the file COPYING.txt, distributed with this software.
 #-----------------------------------------------------------------------------
 
 #-----------------------------------------------------------------------------
 # Code
 #-----------------------------------------------------------------------------
 
 
 __all__ = ['citation2latex']
 
 
 def citation2latex(s):
     """Parse citations in Markdown cells.
     
     This looks for HTML tags having a data attribute names `data-cite`
     and replaces it by the call to LaTeX cite command. The tranformation
     looks like this:
     
     `<cite data-cite="granger">(Granger, 2013)</cite>`
     
     Becomes
     
     `\\cite{granger}`
     
     Any HTML tag can be used, which allows the citations to be formatted
     in HTML in any manner.
     """
     try:
         from lxml import html
     except ImportError:
         return s
 
     tree = html.fragment_fromstring(s, create_parent='div')
     _process_node_cite(tree)
     s = html.tostring(tree)
     if s.endswith('</div>'):
         s = s[:-6]
     if s.startswith('<div>'):
         s = s[5:]
     return s
 
 
 def _process_node_cite(node):
     """Do the citation replacement as we walk the lxml tree."""
     
     def _get(o, name):
-        value = getattr(o, name)
+        value = getattr(o, name, None)
         return '' if value is None else value
     
     if 'data-cite' in node.attrib:
         cite = '\cite{%(ref)s}' % {'ref': node.attrib['data-cite']}
         prev = node.getprevious()
         if prev is not None:
             prev.tail = _get(prev, 'tail') + cite + _get(node, 'tail')
         else:
             parent = node.getparent()
             if parent is not None:
                 parent.text = _get(parent, 'text') + cite + _get(node, 'tail')
         try:
             node.getparent().remove(node)
         except AttributeError:
             pass
     else:
         for child in node:
             _process_node_cite(child)