KeyError: 1

[Remy Blank]

How to Reproduce

While doing a GET operation on /ticket/2635, Trac issued an internal error.

The error happens when trying to view the diffs of comment edits on comment:5:ticket:2635.

It would be very helpful to get the output of the following query:

SELECT time,author,field,oldvalue FROM ticket_change WHERE ticket=2635;

(Or a dump of the ticket_change table for ticket=2635)

Request parameters:

{'action': u'comment-diff', 'cnum': u'5', 'id': u'2635', 'version': u'2'}

User Agent was: Mozilla/5.0 (Windows; U; Windows NT 5.1; en-US; rv:1.9.1.7) Gecko/20091221 Firefox/3.5.7

System Information

Trac	0.12dev-r9078
Python	2.5.2 (r252:60911, Oct 5 2008, 19:29:17) [GCC 4.3.2]
setuptools	0.6c9
psycopg2	2.0.8
Genshi	0.6dev-r1092
Babel	0.9.4
Pygments	1.1.1dev-20091217
Subversion	1.5.1 (r32289)
Docutils	0.6
jQuery	1.3.2

Enabled Plugins

Python Traceback

Traceback (most recent call last):
  File "build/bdist.linux-x86_64/egg/trac/web/main.py", line 495, in _dispatch_request
    dispatcher.dispatch(req)
  File "build/bdist.linux-x86_64/egg/trac/web/main.py", line 227, in dispatch
    resp = chosen_handler.process_request(req)
  File "build/bdist.linux-x86_64/egg/trac/ticket/web_ui.py", line 168, in process_request
    return self._process_ticket_request(req)
  File "build/bdist.linux-x86_64/egg/trac/ticket/web_ui.py", line 471, in _process_ticket_request
    return self._render_comment_diff(req, ticket, data, cnum)
  File "build/bdist.linux-x86_64/egg/trac/ticket/web_ui.py", line 945, in _render_comment_diff
    old_text = history[old_version]['value']
KeyError: 1

[Christian Boos]

If you don't have the REPORT permissions, tell me, I'll add them. In the meantime see: {38}

This issue (editing a comment which get saved under another one) has most likely to do with old unnumbered comments, hence again the probable need to add a renumber db upgrade step.

[Remy Blank]

Replying to cboos:

If you don't have the REPORT permissions, tell me, I'll add them.

Heh, I hadn't thought of that ;) I'm not using reports nearly often enough. Thanks!

This issue (editing a comment which get saved under another one) has most likely to do with old unnumbered comments, hence again the probable need to add a renumber db upgrade step.

Yes, I'll probably do that. Still, I'd prefer that it doesn't throw an internal error even without the upgrade.

[Christian Boos]

Actually the comments numbering seem to be fine:

12:34:51	anonymous	type	defect

15:47:03	mgood	comment	

09:25:22	Dave Matthews	comment	

11:17:17	cboos	comment	
11:17:17	cboos	keywords	
11:17:17	cboos	owner	jonas

20:18:47	cboos	_comment0	I'm going to need ...
20:18:47	cboos	_comment1	Being able to link to ...
20:18:47	stevegt	comment	

10:36:25	stevegt@terraluna.org	comment	

10:37:26	anonymous	comment	

00:50:21	anonymous	cc	

20:22:21	cboos	milestone	
20:22:21	cboos	comment	9
...

so there must be an off by one error somewhere.

[Remy Blank]

Replying to cboos:

Actually the comments numbering seem to be fine:

Not quite. The edits at 12:34:51 and 00:50:21 don't have a comment field, and that's what I happen to use to number the comments in case the comment number is not available in oldvalue (I was mislead by this​).

Let's see if I can find a more robust way to count edits…

[Remy Blank]

Fixed in [9107], together with unit tests for all sorts of special cases (which I should have added from the start).

Let's hope that I have finally covered all the pathological cases.

[Christian Boos]

I saw this one in the logs this morning:

[pid  1121933648] 2010-03-22 10:28:50,308 Trac[main] ERROR: Internal Server Error:
Traceback (most recent call last):
  File "build/bdist.linux-x86_64/egg/trac/web/main.py", line 504, in _dispatch_request
    dispatcher.dispatch(req)
  File "build/bdist.linux-x86_64/egg/trac/web/main.py", line 235, in dispatch
    resp = chosen_handler.process_request(req)
  File "build/bdist.linux-x86_64/egg/trac/ticket/web_ui.py", line 169, in process_request
    return self._process_ticket_request(req)
  File "build/bdist.linux-x86_64/egg/trac/ticket/web_ui.py", line 472, in _process_ticket_request
    return self._render_comment_diff(req, ticket, data, cnum)
  File "build/bdist.linux-x86_64/egg/trac/ticket/web_ui.py", line 948, in _render_comment_diff
    new_text = history[new_version]['value']
KeyError: 1

for the request:

207.46.204.227 trac.edgewall.org - [22/Mar/2010:10:28:50 +0100] "GET /ticket/8902?action=comment-diff&cnum=5&version=1 HTTP/1.0" 500 9085 "-" "msnbot/2.0b (+http://search.msn.com/msnbot.htm)"

(reproducible)

[Christian Boos]

Ok, there's no previous version for ticket:8902#comment:5 (not sure how they got the link), but perhaps we shouldn't throw an internal error in this case, perhaps rather a ResourceNotFound.

[Remy Blank]

Replying to cboos:

we shouldn't throw an internal error in this case, perhaps rather a ResourceNotFound.

Done in [9392].