[OpenLayers-Users] BBOX strategy with GeoJSON points

[Puneet Kishor]

Thanks Arnd, this really helps. Perhaps extending the .Format.GeoJSON() object to allow providing a custom read function might be worthwhile.
 

On Mar 17, 2012, at 2:18 PM, Arnd Wippermann wrote:

> Hi Puneet,
> 
> You can overwrite the read function of the format. 
> Then you should be able to grab the geojson from your response.
> 
> 
> //function read from OpenLayers-2.11\lib\OpenLayers\Format\GeoJSON.js
> function myReadFunction(json, type, filter)
> {
>    type = (type) ? type : "FeatureCollection";
>    var results = null;
> 
>    //instead
>    /*
>    if (typeof json == "string") {
>        obj = OpenLayers.Format.JSON.prototype.read.apply(this,
>                                                          [json, filter]);
>    } else { 
>        obj = json;
>    } 
>    */   
> 
>    //try this
>    var obj = eval('(' + json + ')').result.geojson;
> 
>    //above no changes
>    if(!obj) {
>        OpenLayers.Console.error("Bad JSON: " + json);
>    } else if(typeof(obj.type) != "string") {
>        OpenLayers.Console.error("Bad GeoJSON - no type: " + json);
>    }
>    else if(this.isValidType(obj, type)) {
> ...
> ...
>            break;
>        }
>    }
>    return results;
> }
> 
> var vec = new OpenLayers.Layer.Vector(
> 	"My Vector Layer", {
> 		strategies: [new OpenLayers.Strategy.BBOX()],
> 		protocol: new OpenLayers.Protocol.HTTP({
>            url: "some_features.geojson",
>            params: {
> 				"a": "value of a",
> 				"b": function() {
> 					return a_value_for_b;
> 				}
>            format: new OpenLayers.Format.GeoJSON({read:myReadFunction})
>        })
>    }
> );
> 
> map.addLayer(vec);
> 
> Arnd
>