Load information about a feature

Question

I must mention first of all that I am very new to this area... I am developing a GIS application. I created a simple map using geoserver with openlayers, it is all working through apache tomcat - and is connected to postgis/postgresql database. When I click on a point (the points represent weather stations - and stored in database) it is set to display the tablewith all the data like: fid, station_name etc. What I want to do is - to store station_name(I clicked on) in a variable and use for my needs. In this case I was trying to break response.responseText in parts, and get it from there but it never worked... response.responseText - returns all the information and creates the tables. I need to only get ONE value from database. Any ideas!? Any help greatly appriciated!!!

Here is the code: In this part it is set to read a click and make a response:

map.events.register('click', map, function (e) {

                document.getElementById('nodelist').innerHTML = "Loading... please wait...";
                var params = {
                    REQUEST: "GetFeatureInfo",
                    EXCEPTIONS: "application/vnd.ogc.se_xml",
                    BBOX: map.getExtent().toBBOX(),
                    SERVICE: "WMS",
                    INFO_FORMAT: 'text/html',
                    QUERY_LAYERS: map.layers[0].params.LAYERS,
                    FEATURE_COUNT: 50,
                    Layers: 'map_with_stations',
                    WIDTH: map.size.w,
                    HEIGHT: map.size.h,
                    format: format,
                    styles: map.layers[0].params.STYLES,
                    srs: map.layers[0].params.SRS};

                // handle the wms 1.3 vs wms 1.1 madness
                if(map.layers[0].params.VERSION == "1.3.0") {
                    params.version = "1.3.0";
                    params.j = parseInt(e.xy.x);
                    params.i = parseInt(e.xy.y);
                } else {
                    params.version = "1.1.1";
                    params.x = parseInt(e.xy.x);
                    params.y = parseInt(e.xy.y);
                }

                // merge filters
                if(map.layers[0].params.CQL_FILTER != null) {
                    params.cql_filter = map.layers[0].params.CQL_FILTER;
                } 
                if(map.layers[0].params.FILTER != null) {
                    params.filter = map.layers[0].params.FILTER;
                }
                if(map.layers[0].params.FEATUREID) {
                    params.featureid = map.layers[0].params.FEATUREID;
                }
                OpenLayers.loadURL("http://localhost:82/geoserver/wms", params, this, setHTML, setHTML);
                OpenLayers.Event.stop(e);
            });
        }

        // sets the HTML provided into the nodelist element
        function setHTML(response){

            document.getElementById('nodelist').innerHTML = response.responseText;



        };

Answer 1

Although your method should work, since you are already using OpenLayers you should use OpenLayers.Control.WMSGetFeatureInfo , here is an example from a previous, but different question here in gis.stackexchange.com:

var queryableMapLayers = [];
var getFeatureControl = new OpenLayers.Control.WMSGetFeatureInfo({
  url: your_wms_url.here // Your WMS server url here,
  drillDown: false, // Or true if you want drill down (see the docs)
  hover: false, // Or true if you want but bear in mind this could get chatty
  layers: queryableMapLayers,
  eventListeners: {
    getfeatureinfo: function (event) {
      // Code here if you want to process the results
      // From openlayers docs:
      // Triggered when a GetFeatureInfo response is received.  The event                     
      // object has a text property with the body of the response (String), 
      // a features property with an array of the parsed features, an xy 
      // property with the position of the mouse click or hover event that 
      // triggered the request, and a request property with the request 
      // itself.  If drillDown is set to true and multiple requests were 
      // issued to collect feature info from all layers, text and request 
      // will only contain the response body and request object of the last request.
    },
    beforegetfeatureinfo: function(event) {
      // Code here to set the content of queryableMapLayers
      // The event object will contain xy of mouse click
    },
    nogetfeatureinfo: function(event) {
      // Code here if no queryable layers are found
    }
  } 
});

// Add the control to your map
map.addControl(getFeatureControl);

Also look at the OpenLayers.Control.WMSGetFeatureInfo.request method for a customized request(like a fixed location request, or one not coming from a click event)

Answer 2

Also you could do

layers: [layer_1, layer_2],
vendorParams: {propertyName:['column_name1', 'column_name2', 'column_name3']}

replace 'layer_1' and 'layer_2' with wms layers you want to query and 'column_name1'...column_name3' with real column names of those tables.

After this getfeatureinfo will get only data from those fields.