[GIS] How to split a feature and save back to database

openlayers-2postgis-1.5

How to split/cut a polygon through OpenLayers split method and same editing save to the PostGIS?

Best Answer

OpenLayer's Split control is straight forward. You pass it a layer in the contructor and the control will split it.

If your layer has ONE feature and you split it using the control you will end up with TWO features in the layer.

Once youre ready to save to PostGIS, you can write those features to a number of different formats WKT, KML, GML, etc. And pass that to your backend webservice wether it be a GeoServer WFS-T or a PHP, C# or other back-end handler/service that will save the features to your postGIS database.

Click here for an OpenLayers 2 Split Feature Example

Save as string:

function GetKMLFromFeatures(features) {
    var format = new OpenLayers.Format.KML({
        'maxDepth':10,
        'extractStyles':true,
        'internalProjection': map.baseLayer.projection,
        'externalProjection': new OpenLayers.Projection("EPSG:4326")
    });

    return format.write(features);
}

Download the string:

But if what you actually want is to download a KML file of the string, you will face the issue that the KML string already resides on the client's browser so you can't download it because it's already there. To Download it you'll have to send it back to a handler on the server side to return a response with the proper file extension and content type application/kml;

This will initiate a browser download.

Check my more indepth answer on StackOverflow.

Update:

A comment on SO pointed me to a new way of doing this. Though, make sure browser compatibility is appropriate.

[GIS] OpenLayers: how to save added point in server side

I found a cool sample that illustrates the handling. Take a look at this (the source code :-D) http://edgemaster.dev.openstreetmap.org/oldemo/10.htm

Your vector layer needs a server part two handle the persistence. The save strategy only triggers the write back.

/* from the sample source */
var scribble = new OpenLayers.Layer.Vector("Scribble", {
    protocol: new OpenLayers.Protocol.HTTP({
        url: "featureserver/featureserver.cgi/scribble",
        format: new OpenLayers.Format.GeoJSON()
    }),
    strategies: [new OpenLayers.Strategy.BBOX(), new OpenLayers.Strategy.Save({auto: true})],
    projection: wgs
});
map.addLayer(scribble);

Best Answer

Related Solutions

[GIS] Openlayers create, edit and save/export to kml

Save as string:

Download the string:

Update:

[GIS] OpenLayers: how to save added point in server side

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