Trac: diff view on ticket text causes internal error

[ichthyo]

Following the "diff.." link on description changes in the ticket changelog causes a python stacktrace. From a quick investigation it looks as if the mastertickets plugin is the culprit. Development on this plugin seems to have stalled since a year, so, if this gets a problem, we should fix it ourselves...

Python Traceback
Most recent call last:

• File "/usr/lib/python2.5/site-packages/trac/web/main.py", line 423, in _dispatch_request

      418. try:
      419. if not env and env_error:
      420. raise HTTPInternalError(env_error)
      421. try:
      422. dispatcher = RequestDispatcher(env)
      423. dispatcher.dispatch(req)
      424. except RequestDone:
      425. pass
      426. resp = req._response or []
      427.  
      428. except HTTPException, e:
     Local variables:
     Name	Value
     after 	[u' except RequestDone:', u' pass', u' resp = ...
     before 	[u' try:', u' if not env and env_error:', u' raise ...
     dispatcher 	<trac.web.main.RequestDispatcher object at 0x1b12790>
     e 	KeyError('fields',)
     env 	<trac.env.Environment object at 0x1657390>
     env_error 	None
     exc_info 	(<type 'exceptions.KeyError'>, KeyError('fields',), <traceback object at ...
     filename 	'/usr/lib/python2.5/site-packages/trac/web/main.py'
     frames 	[{'function': '_dispatch_request', 'lines_before': [u' try:', u' ...
     has_admin 	True
     line 	u' dispatcher.dispatch(req)'
     lineno 	422
     message 	u"KeyError: 'fields'"
     req 	<Request "GET u'/ticket/414'">
     resp 	[]
     tb 	<traceback object at 0x1ed7f38>
     tb_hide 	None
     traceback 	'Traceback (most recent call last):\n File   
  

• File "/usr/lib/python2.5/site-packages/trac/web/main.py", line 209, in dispatch

   204. if req.session:
   205. req.session.save()
   206. req.display(template, content_type or 'text/html')
   207. else: # Genshi
   208. template, data, content_type = \
   209. self._post_process_request(req, *resp)
   210. if 'hdfdump' in req.args:
   211. req.perm.require('TRAC_ADMIN')
   212. # debugging helper - no need to render first
   213. from pprint import pprint
   214. out = StringIO()
  Local variables:
  Name	Value
  chosen_handler 	<trac.ticket.web_ui.TicketModule object at 0x1b12850>
  chrome 	<trac.web.chrome.Chrome object at 0x19c3410>
  e 	TypeError("'NoneType' object is unsubscriptable",)
  err 	(<type 'exceptions.KeyError'>, KeyError('fields',), <traceback object at ...
  handler 	<trac.ticket.web_ui.TicketModule object at 0x1b12850>
  req 	<Request "GET u'/ticket/414'">
  resp 	('diff_view.html', {'comment': None, 'longcol': '', 'new_version': 1, ...
  self 	<trac.web.main.RequestDispatcher object at 0x1b12790>
  

• File "/usr/lib/python2.5/site-packages/trac/web/main.py", line 299, in _post_process_request

   294. # Trac 0.10, only filters with same arity gets passed real values.
   295. # Errors will call all filters with None arguments,
   296. # and results will not be not saved.
   297. extra_arg_count = arity(f.post_process_request) - 2
   298. if extra_arg_count == nbargs:
   299. resp = f.post_process_request(req, *resp)
   300. elif nbargs == 0:
   301. f.post_process_request(req, *(None,)*extra_arg_count)
   302. return resp
   303.  
   304.  
  Local variables:
  Name	Value
  args 	('diff_view.html', {'comment': None, 'longcol': '', 'new_version': 1, ...
  extra_arg_count 	3
  f 	<mastertickets.web_ui.MasterTicketsModule object at 0x1b12dd0>
  nbargs 	3
  req 	<Request "GET u'/ticket/414'">
  resp 	('diff_view.html', {'comment': None, 'longcol': '', 'new_version': 1, ...
  self 	<trac.web.main.RequestDispatcher object at 0x1b12790>
  

• File "/var/local/trac/trac-env/plugins/TracMasterTickets-2.1.3-py2.5.egg/mastertickets/web_ui.py", line 64, in post_process_request

     Local variables:
     Name	Value
     change 	{'diffs': [], 'old': {'path': 'Ticket #414', 'href': ...
     content_type 	None
     data 	{'comment': None, 'longcol': '', 'new_version': 1, 'num_changes': 1, ...
     links 	<mastertickets.model.TicketLinks #414 blocking=[77] blocked_by=[]>
     req 	<Request "GET u'/ticket/414'">
     self 	<mastertickets.web_ui.MasterTicketsModule object at 0x1b12dd0>
     template 	'diff_view.html'
     tkt 	<trac.ticket.model.Ticket object at 0x1e0b390>
  

[ichthyo]

Just looking at mastertickets/web_ui.py, there is a blatant error. Why the hell can't people stop writing these kind of Train wreck sequences

    def post_process_request(self, req, template, data, content_type):
...
...
            for change in data.get('changes', []):
                for field, field_data in change['fields'].iteritems():

obviously in this case the change was Null or an empty object

... well, anyone in the mood to fix it?

[ichthyo]

solved by upgrading to Trac 0.12.2