[GIS] Using custom filters (server side) for OpenLayers Vector Layer

filterlayersopenlayers-2vector

I have a vector layer in openlayers with source in GEOJSON (custom php server, which I have in complete control) and BBOX strategy.

Vector points contain point sources which have different attributes. I want to implement some filters by one or two attributes. I can manage server side php code – for e.g. I can get the filters by adding URL parameters to existing url like: 

Existing URL: mywebservice.php
Filtered URL: mywebservice.php?someattributte=somevalue

How do I implement it on the OpenLayers side?

My code is as follows:

            var in_options = {
                'internalProjection': EPSG_900913,
                'externalProjection': EPSG_4326
            };
            var ems_sources = new OpenLayers.Layer.Vector(EMS_SOURCES_TITLE, {
                strategies: [
                             new OpenLayers.Strategy.BBOX({
                                 resFactor: 2,
                                 active: true,
                                 autoActivate: true,
                                 ratio: 1.3
                             })

                         ],
                 protocol: new OpenLayers.Protocol.HTTP({
                     url: EMS_SOURCES_WS,
                     callbackKey: 'callback',
                     format: new OpenLayers.Format.GeoJSON(in_options)
                 })
            });

Best Answer

You can pass params object in the OpenLayers.Protocol.HTTP. See here http://dev.openlayers.org/docs/files/OpenLayers/Protocol/HTTP-js.html#OpenLayers.Protocol.HTTP.params

your protocol part of code should look like

protocol: new OpenLayers.Protocol.HTTP({
                 url: EMS_SOURCES_WS,
                 callbackKey: 'callback',
                 format: new OpenLayers.Format.GeoJSON(in_options),
                 params: {someattributte:somevalue}
             })
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