specify coordinate system on openlayers Filter

Question

Is there anyway to specify which coordinate system to use with a filter?

using the following filter:

new OpenLayers.Filter.Spatial({
    property: "boundsText",
    type: OpenLayers.Filter.Spatial.INTERSECTS,
    value: geom
})

Produces this HTTP POST to my GeoServer:

<ogc:intersects>
<ogc:propertyname>bounds</ogc:propertyname>
<gml:polygon xmlns:gml="http://www.opengis.net/gml" srsName="EPSG:4326">
    <gml:outerboundaryis>
        <gml:linearring>
            <gml:coordinates decimal="." cs="," ts=" ">-7670608.6611,2132898.8368875 -6261721.356,254382.4300875 -6653078.94075,6633511.0615125 -12758257.26285,6790054.0954125 -7670608.6611,2132898.8368875</gml:coordinates>
        </gml:linearring>
    </gml:outerboundaryis>
</gml:polygon>
</ogc:intersects>

and i get the following response error from GeoServer:

-7670608.6611 outside of (-180.0,180.0)

How can i change whatever coordinate system is being sent in my filter to decimal degrees?

Answer 1

I was able to do it by using the transform() operation on the geometry like so:

var geographic = new OpenLayers.Projection("EPSG:4326");
var mercator = new OpenLayers.Projection("EPSG:900913");

new OpenLayers.Filter.Spatial({
    property: "boundsText",
    type: OpenLayers.Filter.Spatial.INTERSECTS,
    value: geom.transform(mercator, geographic)
})

Key line being:

value: geom.transform(mercator, geographic)

You might actually want to add the clone() (depending on your situation) so it won't actually transform your existing geometry:

value: geom.clone().transform(mercator, geographic)

Answer 2

You can specify coordinate system to use with a filter using "projection" option.

new OpenLayers.Filter.Spatial({
    property: "boundsText",
    type: OpenLayers.Filter.Spatial.INTERSECTS,
    value: geom,
    projection:"EPSG:900913"
})

See: http://openlayers.org/dev/examples/filter.html