display a selected WMS Info

Question

I am using the WMSGetFeatureInfo and I am also obtaining the Info of the base raster and i do not need that. Is it possible to obtain the FeatureInfo of only selected WMS features?

How can I modify this code to accommodate only selected WMS layer?

info = new OpenLayers.Control.WMSGetFeatureInfo({
            url : 'http://niles.iplantcollaborative.org:8080/geoserver/wms',
            title : 'Identify features by clicking',
            queryVisible : true,
            eventListeners : {
            getfeatureinfo : function(event) {
            map.addPopup(new OpenLayers.Popup.FramedCloud("chicken", map.getLonLatFromPixel(event.xy), null, event.text, null, true));
            }
            }
            });
            map.addControl(info);
            info.activate();

UPDATE 2.0

I have added the code,

gfLayers = [];
            var lyr = map.layers;

            for(var a=0; a < lyr.length; a++){
                if(lyr[a].CLASS_NAME == "OpenLayers.Layer.WMS" && lyr[a].visibility == true){
                    if(lyr[a].isBaseLayer == false){
                        gfLayers.push(lyr[a].name);
                    }

                } 
            };

            info = {
                hover : new OpenLayers.Control.WMSGetFeatureInfo({
                    url : 'http://niles.iplantcollaborative.org:8080/geoserver/wms',
                    title : 'Identify features by clicking',
                    //layers : gfLayers,
                    layers : [pima, carib],
                    queryVisible : true,
                    hover: true,
                    eventListeners : {
                        getfeatureinfo : function(event) {
                            deletePopUp();
                            popup = new OpenLayers.Popup.FramedCloud("popInfo", map.getLonLatFromPixel(event.xy), null, event.text, null, true);
                            map.addPopup(popup);
                        }
                    }
                })
            };
            map.addControl(info.hover);
            info.hover.activate();

Now I am getting Empty PopUps. not sure why?

Answer 1

I think the answer is covered in this example's source code : http://dev.openlayers.org/examples/getfeatureinfo-control.html

Please pay attention to "layers: [water]" at this code piece :

infoControls = {
            click: new OpenLayers.Control.WMSGetFeatureInfo({
                url: 'http://demo.opengeo.org/geoserver/wms', 
                title: 'Identify features by clicking',
                layers: [water],
                queryVisible: true
            }),
            hover: new OpenLayers.Control.WMSGetFeatureInfo({
                url: 'http://demo.opengeo.org/geoserver/wms', 
                title: 'Identify features by clicking',
                layers: [water],
                hover: true,
                // defining a custom format options here
                formatOptions: {
                    typeName: 'water_bodies', 
                    featureNS: 'http://www.openplans.org/topp'
                },
                queryVisible: true
            })
        }

And :

function toggleLayers(element) {
        for (var key in infoControls) {
            var control = infoControls[key];
            if (element.value == 'Specified') {
                control.layers = [water];
            } else {
                control.layers = null;
            }
        }
    } 

So if you don't define the layer that you are interested then it requests info from all layers for the selected point.

Answer 2

try this:

gfLayers = [];
var lyr = map.layers;

for(var a= 0; a < lyr.length; a++){
    if(lyr[a].CLASS_NAME == "OpenLayers.Layer.WMS" && lyr[a].visibility == true){
           gfLayers.push(lyr[a].name);
    }

    };

then add this array to in your layers defination in WMSGetFeatureInfo layers as

...
layers: gfLayers,
queryVisible: true
...

i hope it helps you...