KML fails to render classes of vector layer

[davide85]

When we try to render a vector layer defined by several classes inside the mapfile, the KML ouput doesn't show the different styles. It seems like all the expression classes are evaluated as incorrect by the mapserver parser. Indeed, if we try to bypass the "yyparse" status value inside maputil.c, the KML output is instead set up correctly. To bypass this problem we set up yyparse to 0, in this way the output is correct and all classes with their styles are correctly rendered. Below an example of an expression that is not parsed while it is correct:

class
  name ' < 20'
  expression (([sll] < 20))
  style
    color 50 243 50
  end
end

[chodgson]

I have seen the same problem. Our expression is a bit more complicated:

EXPRESSION (('[NATION_ENGLISH_NAME]' eq 'Canada') and ('[STATUS]' ne 'Canadian Waters') and ('[NAME]' ne 'British Columbia'))

The same layer renders fine as png, but fails to parse the expression when output using kml - here's the log output:

[Mon Sep 26 11:23:30 2011].807000 msDrawMap(): rendering using outputformat named png (AGG/PNG). [Mon Sep 26 11:23:30 2011].823000 msDrawMap(): WMS/WFS set-up and query, 0.016s [Mon Sep 26 11:23:30 2011].995000 msDrawMap(): Layer 0 (DBM_7H_MIL_POLITICAL), 0.172s [Mon Sep 26 11:23:30 2011].995000 msDrawMap(): Drawing Label Cache, 0.000s [Mon Sep 26 11:23:30 2011].995000 msDrawMap() total time: 0.188s [Mon Sep 26 11:23:31 2011].182000 msSaveImage(stdout) total time: 0.187s [Mon Sep 26 11:23:31 2011].182000 mapserv request processing time (msLoadMap not incl.): 0.375s [Mon Sep 26 11:23:31 2011].182000 msFreeMap(): freeing map at 03FBEBC8. [Mon Sep 26 11:23:38 2011].698000 CGI Request 36 on process 6440 [Mon Sep 26 11:23:38 2011].698000 msDrawMap(): rendering using outputformat named kml (KML). [Mon Sep 26 11:23:38 2011].698000 msDrawMap(): WMS/WFS set-up and query, 0.000s [Mon Sep 26 11:23:38 2011].729000 yyparse(): Expression parser error. syntax error [Mon Sep 26 11:23:38 2011].729000 msEvalExpression: Expression parser error. Failed to parse expression: ('[NATION_ENGLISH_NAME]' eq 'Canada') and ('[STATUS]' ne 'Canadian Waters') and ('[NAME]' ne 'British Columbia') [Mon Sep 26 11:23:38 2011].729000 yyparse(): Expression parser error. syntax error

[chodgson]

Sorry, here's that log output with better formatting:

[Mon Sep 26 11:23:30 2011].807000 msDrawMap(): rendering using outputformat named png (AGG/PNG).
[Mon Sep 26 11:23:30 2011].823000 msDrawMap(): WMS/WFS set-up and query, 0.016s
[Mon Sep 26 11:23:30 2011].995000 msDrawMap(): Layer 0 (DBM_7H_MIL_POLITICAL), 0.172s
[Mon Sep 26 11:23:30 2011].995000 msDrawMap(): Drawing Label Cache, 0.000s
[Mon Sep 26 11:23:30 2011].995000 msDrawMap() total time: 0.188s
[Mon Sep 26 11:23:31 2011].182000 msSaveImage(stdout) total time: 0.187s
[Mon Sep 26 11:23:31 2011].182000 mapserv request processing time (msLoadMap not incl.): 0.375s
[Mon Sep 26 11:23:31 2011].182000 msFreeMap(): freeing map at 03FBEBC8.
[Mon Sep 26 11:23:38 2011].698000 CGI Request 36 on process 6440
[Mon Sep 26 11:23:38 2011].698000 msDrawMap(): rendering using outputformat named kml (KML).
[Mon Sep 26 11:23:38 2011].698000 msDrawMap(): WMS/WFS set-up and query, 0.000s
[Mon Sep 26 11:23:38 2011].729000 yyparse(): Expression parser error. syntax error
[Mon Sep 26 11:23:38 2011].729000 msEvalExpression: Expression parser error. Failed to parse expression: ('[NATION_ENGLISH_NAME]' eq 'Canada') and ('[STATUS]' ne 'Canadian Waters') and ('[NAME]' ne 'British Columbia')
[Mon Sep 26 11:23:38 2011].729000 yyparse(): Expression parser error. syntax error
}}

[chodgson]

msTokenizeExpression is being called twice for kml output (and possibly others?), resulting in the tokens being duplicated in the expressionObj, and thus the expression tree is not valid, and fails to parse. eg. ('[NAME]' eq 'a') ends up as this list of tokens [NAME], eq, "a", [NAME], eq, "a" - it's not duplicated like this for png output.

I've tracked it down to msLayerWhichItems() being called twice, the second time by msDrawVectorLayer(). I haven't been able to figure out where it is getting called the first time.

Seems like we'd be better off not calling msLayerWhichItems() two times... but an alternative fix might be to just check if the expression is already tokenized before doing it again (or at least replacing the existing tokenization instead of tacking it on the end of the existing one).

I'm adding Steve to the CC list as this seems like it related to his revamped expression parsing.

[chodgson]

Just a little more details about my use case - ubuntu linux, mapserver compiled from svn, single shapefile layer, WMS getmap request:

http://localhost/cgi-bin/mapserv-svn
?map=/mapfiles/test/test.map
&request=getMap
&service=wms
&width=500
&height=500
&version=1.3.0
&layers=holypoly
&crs=epsg:4326
&bbox=54,-138,63,-112
&format=kml

[sdlime]

Does anyone have a trivial test case I could use to debug this? msLayerWhichItems() is not called that many places (layer drawing or layer query code) so it should be that hard to track down.

Steve

[chodgson]

All it takes is a single shapefile layer with a class with an expression in it (not a classitem) in a WMS-enabled mapfile, and do a getmap request with format=kml. I'm away from my regular computer this week, or would attach the mapfile that I was testing with...

[chodgson]

test map file

[chodgson]

Ok I was able to get a hold of my test mapfile and shapefile. I cut out some extraneous garbage from the mapfile that shouldn't have been related, but I haven't tested this exact file. You should be able to use a wms request like the one above to replicate the problem, and then change to format=png and get a valid image back.

Let me know if you can't replicate the problem with this mapfile and shapefile.