[OpenLayers-Users] getFeatureInfo() Only Works on One Layer?

[Arnd Wippermann]

Hi Bill,

You have to delete the blank in QUERY_LAYERS: "us_interstate,us_states" 

A documentation for WMS parameters are availible from OGC. They are
responsibable for WMS, WFS and other standards. 

http://www.opengeospatial.org/standards/wms

Arnd Wippermann



-----Ursprüngliche Nachricht-----
Von: users-bounces at openlayers.org [mailto:users-bounces at openlayers.org] Im
Auftrag von Bill Thoen
Gesendet: Dienstag, 27. Januar 2009 22:59
An: users at openlayers.org
Betreff: [OpenLayers-Users] getFeatureInfo() Only Works on One Layer?

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.

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 beused here?

TIA,
- Bill Thoen

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