ProgrammingError: Cannot operate on a closed cursor

[schodet]

Seen on trac 0.11.7.

File "/usr/lib/python2.6/dist-packages/trac/web/main.py", line 450, in _dispatch_request
  dispatcher.dispatch(req)
File "/usr/lib/python2.6/dist-packages/trac/web/main.py", line 227, in dispatch
  data, content_type)
File "/usr/lib/python2.6/dist-packages/trac/web/chrome.py", line 773, in render_template
  stream.render(method, doctype=doctype, out=buffer)
File "/usr/lib/pymodules/python2.6/genshi/core.py", line 183, in render
  return encode(generator, method=method, encoding=encoding, out=out)
File "/usr/lib/pymodules/python2.6/genshi/output.py", line 58, in encode
  for chunk in iterator:
File "/usr/lib/pymodules/python2.6/genshi/output.py", line 339, in __call__
  for kind, data, pos in stream:
File "/usr/lib/pymodules/python2.6/genshi/output.py", line 826, in __call__
  for kind, data, pos in stream:
File "/usr/lib/pymodules/python2.6/genshi/output.py", line 670, in __call__
  for kind, data, pos in stream:
File "/usr/lib/pymodules/python2.6/genshi/output.py", line 771, in __call__
  for kind, data, pos in chain(stream, [(None, None, None)]):
File "/usr/lib/pymodules/python2.6/genshi/output.py", line 586, in __call__
  for ev in stream:
File "/usr/lib/pymodules/python2.6/genshi/core.py", line 288, in _ensure
  for event in stream:
File "/usr/lib/pymodules/python2.6/genshi/core.py", line 288, in _ensure
  for event in stream:
File "/usr/lib/python2.6/dist-packages/trac/web/chrome.py", line 838, in _strip_accesskeys
  for kind, data, pos in stream:
File "/usr/lib/pymodules/python2.6/genshi/core.py", line 288, in _ensure
  for event in stream:
File "/usr/lib/python2.6/dist-packages/trac/web/chrome.py", line 827, in _generate
  for kind, data, pos in stream:
File "/usr/lib/pymodules/python2.6/genshi/core.py", line 288, in _ensure
  for event in stream:
File "/usr/lib/pymodules/python2.6/genshi/core.py", line 288, in _ensure
  for event in stream:
File "/usr/lib/pymodules/python2.6/genshi/filters/transform.py", line 686, in _unmark
  for mark, event in stream:
File "/usr/lib/pymodules/python2.6/genshi/filters/transform.py", line 1152, in __call__
  for subevent in self._inject():
File "/usr/lib/pymodules/python2.6/genshi/filters/transform.py", line 1042, in _inject
  content = content()
File "/usr/local/lib/python2.6/dist-packages/ExtendedVersionTracPlugin-0.0-py2.6.egg/extendedversion/milestone.py", line 83, in apply_version
  return self._version_display(req, buffer.events[1][1])
File "/usr/local/lib/python2.6/dist-packages/ExtendedVersionTracPlugin-0.0-py2.6.egg/extendedversion/milestone.py", line 90, in _version_display
  cursor.execute("SELECT version FROM milestone_version WHERE milestone=%s", (milestone,))
File "/usr/lib/python2.6/dist-packages/trac/db/util.py", line 64, in execute
  return self.cursor.execute(sql_escape_percent(sql), args)
File "/usr/lib/python2.6/dist-packages/trac/db/sqlite_backend.py", line 80, in execute
  result = PyFormatCursor.execute(self, *args)
File "/usr/lib/python2.6/dist-packages/trac/db/sqlite_backend.py", line 59, in execute
  args or [])
File "/usr/lib/python2.6/dist-packages/trac/db/sqlite_backend.py", line 51, in _rollback_on_error
  return function(self, *args, **kwargs)

As a workaround, I temporarily disabled the _version_display function:

extendedversion/milestone.py

@@ -86 +86 @@
         return stream | filter
 
     def _version_display(self, req, milestone):
+        # XXX not working.
+        return []
         cursor = self.env.get_db_cnx().cursor()
         cursor.execute("SELECT version FROM milestone_version WHERE milestone=%s", (milestone,))
         row = cursor.fetchone()

[Ryan J Ollos]

(In [11249]) Fixes #8657: Prevent database connection from being closed by keeping an explicit database object in scope.