[OpenLayers-Users] Using Cross Domain JSON to get around a proxy issue

[Robert Sanson]

Hi Phil
 
I just want to use a BBOX, so no cql filters. Does the Script protocol know to return the response to the callback function?
 
Thanks,
 
Robert

>>> Phil Scadden <p.scadden at gns.cri.nz> 20/09/2011 4:15 p.m. >>>
yes, I've done it with eg.

Instead of
                     wfsProtocol = new OpenLayers.Protocol.WFS.v1_1_0({
                         url: myurl,
                         geometryName: "SHAPE",
                         featurePrefix: myfeaturePrefix,
                         featureType: myfeatureType,
                         srsName: myproj
                     });

I use

                     wfsProtocol = new OpenLayers.Protocol.Script({
                         url: myurl,
                         callbackKey: "format_options",
                         callbackPrefix: "callback:",
                         params: {
                             service: "WFS",
                             version: "1.1.0",
                             srsName: myproj
                             request: "GetFeature",
                             featurePrefix: myfeaturePrefix,
                             typeName: myfeatureType,
                             outputFormat: "json"
                         },
                         filterToParams: function (filter, params) {
                             // example to demonstrate BBOX serialization
                             delete params.cql_filter;
                             if (filter.type === 
OpenLayers.Filter.Spatial.BBOX) {
                                 params.bbox = filter.value.toArray();
                                 if (filter.projection) {
                                     
params.bbox.push(filter.projection.getCode());
                                 }
                             } else if (filter.type === 
OpenLayers.Filter.Spatial.DWITHIN) {
                                 var geom = filter.value.clone();
                                 transformGeometry(geom);
                                 if (geom.x >= -180 && geom.x <= 360 && 
geom.y >= -180 && geom.y <= 360) { // is this a lat long?
                                     var xx = geom.x;
                                     geom.x = geom.y;
                                     geom.y = xx;
                                 }
                                 params.cql_filter = 'DWITHIN(SHAPE,' + 
geom.toString() + ',' + filter.distance + ',meters)';
                             } else if (filter.type === 
OpenLayers.Filter.Spatial.INTERSECTS) {
                                 var geom = filter.value;
                                 transformGeometry(geom);
                                 geom.components[0].swapXY();
                                 params.cql_filter = 'INTERSECTS(SHAPE,' 
+ geom.toString() + ')';
                             } else if 
(OpenLayers.Format.QueryStringFilter) {
                                 var format = new 
OpenLayers.Format.QueryStringFilter({
                                     srsInBBOX: this.srsInBBOX
                                 });
                                 params = format.writecql(filter, 
params, this.options.url.indexOf('server21') > 0);
                             }
                             return params;
                         }
                     });

The complicated bit the filterToParams. If you dont have any filter, 
then no problem. If you do, they you need to convert the filter to CQL. 
The code above handles spatial filters. I havent attempted others. Gets 
complicated fast. CQL filters dont respect SRS (at least on geoserver). 
You have to make sure that any geometry is transformed to native SRS 
(that's what my application function transformGeometry is doing). You 
also have switch x,y if it is lat/long.


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