2

This is part of an interface that uses a box to select features on a WMS Layer. This then writes the name of the features to a div as a list.

var recycling = new OpenLayers.Layer.WMS( 
    "Recycling Sites",
    wmsurl+'?', 
    {layers: 'GeoserverWorkspace:recycling', 'format':'image/png', 'transparent':'true'},
    {'opacity': 1.0, 'isBaseLayer': false, 'visibility': true}
    );  

 select = new OpenLayers.Layer.Vector("Selection", {styleMap: 
            new OpenLayers.Style(OpenLayers.Feature.Vector.style["select"])
        });

map.addLayers([osmap, recycling, select])


var recycling_wfs =  new OpenLayers.Control.GetFeature({
            protocol: OpenLayers.Protocol.WFS({
            url: wfsurl,
            version: "1.1.0",
            featureType: "recycling",
            featurePrefix: "GeoserverWorkspace",
            srsName: "EPSG:27700",
            geometryName: "wkb_geometry",
            maxFeatures: 50,
            click: true
            }),     
            box: true
}); 

map.addControl(recycling_wfs);  

recycling_wfs.events.register("featuresselected",this, showInfo);

recycling_wfs.activate();

function showInfo(e) {

    // assign features object to a variable

    var features = e.object.features;

    //properties are accessed by using the attibutes property
    var selectedSites = "";

        for(var fid in features){
          var site = features[fid].attributes;
          var siteName = site.name;
          selectedSites += siteName + " ";
        }

    document.getElementById('responseText').innerHTML = "Recycling Site: " + selectedSites;
}

I am confused about the event object that is returned by the featuresselected event, to the callback function showInfo(). According to the OpenLayers documentation this should be an array. So if I select 2 features I should be able to access the first name by doing the following

var name = e.object.features[0].attributes.name;

However this returns an error of e.object.features[0] undefined. I am able to get the feature name if I use a For..In and iterate through the event.object.features object. Then use the resulting fid to access the feature, like so

var name = e.object.features[fid].attributes.name

Is this the correct way to access the event.object's features or have I missed somthing?

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2 Answers 2

Reset to default
4

replace the following line:

var features = e.object.features;

for: 

var features = e.features;
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1
  • 1
    That does the trick. Altought the openlayers docs says that features are accessed via event.object.
    – Peter Campbell
    Commented Sep 3, 2012 at 9:03
1

try this:

recycling_wfs.events.register("featuresselected",this, function(e) {
console.log(e);
});

that will show you your event and should help you proceed from there

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1
  • I have already done this by creating a temporary variable and assigning e to it, then viewing in firebug. The resulting object, has an object properties and features property. However this does not then act like an array, as in e.object.features[0] is undefined, although e.object.features["fid"] returns the feature object.
    – Peter Campbell
    Commented Sep 3, 2012 at 8:58

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