[OpenLayers-Users] Creating an ogc:Filter combining ogc:BBOX and others

dalsinao dalsinao at yahoo.es
Thu Apr 23 12:08:02 EDT 2009


Hello,

I have seen that there are some changes in the WFS protocol coming in the
next release.
One that particularly affects me is that now the BBOX parameter is not
always added in the WFS requests as before. That's fine, but now I have a
related question.

If you have your own ogc:filter and you want to combine it with BBOX, how
can you do it?
I would like to combine my ogc:filter (static) with the dynamically
generated ogc:BBOX filter (changing according to the viewport I understand). 

Is it possible to do so? and if so, how? 

I have seen the example in wfs-protocol.html, using "strategies" and
"protocol", which at the end produces an HTTP/POST request having an
ogc:filter like the one (for WFS 1.1.0):

<ogc:Filter xmlns:ogc="http://www.opengis.net/ogc">
    <ogc:BBOX>
        <ogc:PropertyName>the_geom</ogc:PropertyName>
        <gml:Envelope xmlns:gml="http://www.opengis.net/gml"
srsName="EPSG:4326">
            <gml:lowerCorner>-37.4060546875 15.1189453125</gml:lowerCorner>
            <gml:upperCorner>-14.9939453125 26.2810546875</gml:upperCorner>
        </gml:Envelope>
    </ogc:BBOX>
</ogc:Filter>

What I would like to do is to combine this ogc:filter with mine to get e.g
something like this:

<ogc:Filter xmlns:ogc="http://www.opengis.net/ogc">
    <ogc:And>
        <ogc:BBOX>
            <ogc:PropertyName>the_geom</ogc:PropertyName>
            <gml:Envelope xmlns:gml="http://www.opengis.net/gml"
srsName="EPSG:4326">
                <gml:lowerCorner>-37.4060546875
15.1189453125</gml:lowerCorner>
                <gml:upperCorner>-14.9939453125
26.2810546875</gml:upperCorner>
            </gml:Envelope>
        </ogc:BBOX>
        <ogc:PropertyIsEqualTo>
            <ogc:PropertyName>Scenario</ogc:PropertyName>
            <ogc:Literal>Demo</
            ogc:Literal>
        </ogc:PropertyIsEqualTo>
    </ogc:And>
</ogc:Filter>


And parallel to this. Is it the intention in the long term to get rid of the
OpenLayers.Layer.WFS layer and use only the OpenLayers.Layer.Vector?

Any info you may have or reference on where to look at will be appreciated.

Thanks in advance and regards.
David
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