[OpenLayers-Users] Layer Query with Mapserver: How to do?

[Arnd Wippermann]

You have only to provide the url and layer for the request, the extent comes
from the click event.

I do something like this:

map.events.register('click', map, function (e)
{
    //MapServer supports Query by Box!
    var QueryByBox = false;

 
//##########################################################################
##
    //set new imgsize and extent for query (it's like a zoom in)
 
//##########################################################################
##
    var QImgSize = {w:100, h:100};

    var tolx      = 5;
    var toly      = 5;
    var tolerance = new OpenLayers.Pixel(tolx, toly);
    var min_px    = new OpenLayers.Pixel(e.xy.x - tolerance.x, e.xy.y +
tolerance.y);
    var max_px    = new OpenLayers.Pixel(e.xy.x + tolerance.x, e.xy.y -
tolerance.y);

    var min_ll    = map.getLonLatFromPixel(min_px);
    var max_ll    = map.getLonLatFromPixel(max_px);

    var BBOX      = Array(min_ll.lon, min_ll.lat, max_ll.lon, max_ll.lat);
 
//##########################################################################
##

    var theUrl = map.layers[map.aktLayer].url;

    if(theUrl.search(/\?/)!=-1)
        var theParams = "&mode=nquery";   //returns all matching results,
mode=query returns only 1 matching result
    else
        var theParams = "?mode=nquery";

    theParams += "&qlayers="         +
map.layers[map.aktLayer].vendor.aktqlayers.replace(/,/,"+");
    theParams += "&layers="          +
map.layers[map.aktLayer].vendor.aktqlayers.replace(/,/,"+");
    theParams += "&map_projection=init="  + map.projection;
    theParams += "&mapext="          + BBOX.join("+");
    theParams += "&imgext="          + BBOX.join("+");
    theParams += "&map_size="        + QImgSize.w + "+" + QImgSize.h;
    theParams += "&imgxy="           + QImgSize.w + "+" + QImgSize.h;
    if(QueryByBox==true)
        theParams += "&imgbox="          + "0+0+" + QImgSize.w + "+" +
QImgSize.h;
    else
    {
        theParams += "&img.x="           + QImgSize.w/2;
        theParams += "&img.y="           + QImgSize.h/2;
    }
    window.open(theUrl + theParams);
});
 
Arnd Wippermann