[thuban-Bugs][696] Uncaught exception when trying to export a mapfile twice

[thuban-bugs@wald.intevation.org]

Bugs item #696, was opened at 2008-07-27 02:57
Status: Open
Priority: 3
Submitted By: Anthony Lenton (elachuni)
Assigned to: Nobody (None)
Summary: Uncaught exception when trying to export a mapfile twice 
Resolution: None
Version: None
Category: None


Initial Comment:
If you try to export a map using the umn_mapserver extension twice, an uncaught exception occurs.
The map needs to have at least one non-default classification for error to occur.

To reproduce this bug:
 * Open thuban
 * Add a layer to the map, say Iceland's political.shp
 * Click twice on the only layer in the left bar to bring up the Layer Properties dialog.
 * Select any Classification field, for example Area.
 * Add a singleton classification, and set it up any how.  Extra points for pretty colors.
 * Click Ok to close the Layer Properties dialog.
 * Click on Experimental->MapServer->Create mapfile
 * Click on Experimental->MapServer->Edit mapfile->Map
 * Set some width and height (say 50x50)
 * Click on Experimental->MapServer->Export mapfile
 * Select any filename and click Ok
 * Click on Experimental->MapServer->Export mapfile, again
 * Select any filename (can be the same as before or not) and click Ok.

An unhandled exception occurred:
removeClass(): Child array error. Cannot remove class, invalid index 1
(please report to http://thuban.intevation.org/bugtracker.html)

Traceback (most recent call last):
  File "/home/anthony/svn/thuban/trunk/thuban/Thuban/UI/mainwindow.py", line 300, in invoke_command
    command.Execute(self.Context())
  File "/home/anthony/svn/thuban/trunk/thuban/Thuban/UI/command.py", line 121, in Execute
    apply(self.function, (context,) + self.args + args, kw)
  File "/home/anthony/svn/thuban/trunk/thuban/Extensions/umn_mapserver/mf_export.py", line 163, in export_mapfile
    thuban_to_map(context, theMap)
  File "/home/anthony/svn/thuban/trunk/thuban/Extensions/umn_mapserver/mf_export.py", line 105, in thuban_to_map
    tblayer_to_map(tb_map, map)
  File "/home/anthony/svn/thuban/trunk/thuban/Extensions/umn_mapserver/mf_export.py", line 73, in tblayer_to_map
    map.add_thubanlayer(layer)
  File "/home/anthony/svn/thuban/trunk/thuban/Extensions/umn_mapserver/mapfile.py", line 1071, in add_thubanlayer
    new_layer.remove_allclasses()
  File "/home/anthony/svn/thuban/trunk/thuban/Extensions/umn_mapserver/mapfile.py", line 735, in remove_allclasses
    self._mf_layer.removeClass(i)
  File "/usr/lib/python2.5/site-packages/mapscript.py", line 1114, in removeClass
    def removeClass(*args): return _mapscript.layerObj_removeClass(*args)
MapServerChildError: removeClass(): Child array error. Cannot remove class, invalid index 1

I believe that this is a problem with the umn_mapserver that keeps track of the classes in the map and doesn't realise when the mapObj is created anew underneath, so it tries to clear the classes on an already clear layer when it comes round to exporting the second time.


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http://wald.intevation.org/tracker/?func=detail&atid=105&aid=696&group_id=6