[mapserver-users] getFeatureInfo() Only Works on One Layer?

[Bill Thoen]

I originally asked this on the OpenLayers forum, but was told that this 
is really a Maperver question. So I'll try it here.

I've got a WMS layer that has two sub-layers in it and I'm trying to get 
attribute information from them via a getFeatureInfo request, but I can 
only get one of them to respond at a time. I've looked at the docs at  
http://trac.openlayers.org/wiki/GetFeatureInfo and noticed that you can 
specify several layers with the QUERY_LAYERS parameter, but I'm finding 
that only the one listed first is active. Also, it's not clear what 
layer you specify at the root of the request, but it looks like it's 
supposed to be different from the layers you're querying. Anyway, here's 
what I'm trying:

I open and load the combined layer like so:
 base = new OpenLayers.Layer.WMS(
   "Base",
   "http://192.168.0.250/cgi-bin/mapserv?map=base.map",
   { layers: ["us_states", "us_interstate"] }
 );
 map.addLayer(base);


And here's the request string I'm sending to MapServer:

var url = base.getFullRequestString({
 REQUEST: "GetFeatureInfo",
 EXCEPTIONS: "application/vnd.ogc.se_xml",
 FORMAT: 'png',
 BBOX: map.getExtent().toBBOX(),
 X: event.xy.x,
 Y: event.xy.y,
 INFO_FORMAT: 'text/plain',
 QUERY_LAYERS: "us_interstate, us_states",
 FEATURE_COUNT: 1,
 WIDTH: map.size.w,
 HEIGHT: map.size.h},
 "http://192.168.0.250/cgi-bin/mapserv?map=base.map&");
OpenLayers.loadURL(url, '', this, setHTML);

Note the QUERY_LAYERS line. As shown here, it responds with interstate 
attributes only when I click on an interstate roadway feature, but I get 
nothing when I click on a state. If I reverse the order of these layers 
in the list, then clicking on a state returns attributes from the 
us_states table only. Even if I click on a spot where features in both 
layers coincide, it returns only the attributes for the layer listed first.

Also, setting the FEATURE_COUNT parameter to something higher than 1 just
gives me more results from the single that  is working.

So how do I use multiple layers in the QUERY_LAYERS parameter, or do I 
get only one at a time? Also, I just guessed at using the layer called 
'base' for the getFeatureInfo oject, what is supposed to be used here?

TIA,
- Bill Thoen