[GIS] How to query a PostGIS database through Geoserver and OpenLayers

geoserveropenlayers-2postgis

I've built a web application using OpenLayers, which is connected to my PostGIS database through Geoserver. Now that I'm able to successfully display all of the layers, I'd like to add querying/interactivity capabilities to the map. For instance, I'd like to create a dropdown menu of checkboxes so the user could "Choose X who have done Y", another dropdown to "Choose X who haven't done Y", etc. I'm having trouble figuring out how exactly to add in this functionality. Does anybody know any good resources/examples for how I might go about doing this?

Thanks for your help.

Best Answer

Rather than using your client-side code to query your database (big security risk), I would suggest you use Geoserver's WFS filtering capabilities. Geoserver's WFS implementation supports a number of filtering techniques, including cross-layer filtering through the querylayer extension.

Here is an example implementation. The js in the source is not minified so it is readable.

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You pretty much answered the question yourself: Geoserver has to be running if you want to serve maps on your website. Every time the page is requested, Geoserver has to draw the map/image.

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To Select and Highlight an feature in Openlayers

You can use the WKT format (convert your shapefiles to this format) (QGIS will do this if save the shapefile as csv) Converting Shapefiles to Text (ASCII) files?

enter image description here

    var highlightCtrl = new OpenLayers.Control.SelectFeature(vectors, {
        hover: true,
        highlightOnly: true,
        renderIntent: "temporary",
        eventListeners: {
            beforefeaturehighlighted: report,
            featurehighlighted: report,
            featureunhighlighted: report
        }
    });

    var selectCtrl = new OpenLayers.Control.SelectFeature(vectors,
        {clickout: true}
    );

    map.addControl(highlightCtrl);
    map.addControl(selectCtrl);

    highlightCtrl.activate();
    selectCtrl.activate();

http://openlayers.org/dev/examples/highlight-feature.html

Best Answer

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