How to convert ArcGIS Server JSON to GeoJSON?

Question

I'm creating a web map using Leaflet, and I want to be able to grab feature layers from our ArcServer. I have successfully been able to retrieve a feature class as JSON, but Esri's JSON objects don't follow the GeoJSON standards so they cannot be displayed.

Does anyone know of a conversion script or tool that handles this? If not, I plan on creating a script to convert ArcServer JSON objects to GeoJSON.

Answer 1

OGR:

ogr2ogr -f GeoJSON test.json "http://sampleserver3.arcgisonline.com/ArcGIS/rest/services/Hydrography/Watershed173811/FeatureServer/0/query?where=objectid+%3D+objectid&outfields=*&f=json" OGRGeoJSON

That command will read the query result directly from the URL. You can also supply it with a text file containing your JSON or you can directly supply encoded JSON on the command line. You can of course use ORG Python bindings to automate it within a script if necessary, or the library to do it in code.

Reference: http://www.gdal.org/ogr/drv_geojson.html

Answer 2

ESRI JSON to GeoJSON (for OpenLayers) *Likely to be modified for Leaflet javascript

        //create esri JSON object
    var myReturn = "esriObj = "+xmlHttpGet(restCall, false);
    eval(myReturn);

I can now work with esriObj as a JSON object i.e. esriObj.geometryType. What happens in the xmlHttpGet method? Basically I create a XMLHttpRequest and pass in my REST URL – your can see this code here

3. OK i have my ‘ESRI query’ JSON object now I need to parse the features in this object and essentially create GeoJSON strings which the OpenLayers sample will be happy with – cue the code butchery…


function esriDeserialize(geojson)
{

    var element = document.getElementById('text');
    var type = document.getElementById("formatType").value;
    var features = formats['in'][type].read(geojson);
    var bounds;
    if(features)
    {
        if(features.constructor != Array) {
            features = [features];
        }
        for(var i=0; i<features.length;>
            if (!bounds) {
                bounds = features[i].geometry.getBounds();
            } else {
                bounds.extend(features[i].geometry.getBounds());
            }

        }
        vectors.addFeatures(features);
        //map.zoomToExtent(bounds);
        var plural = (features.length &gt; 1) ? 's' : '';
        //element.value = features.length + ' feature' + plural + ' added'
    } else {
        element.value = 'Bad input ' + type;
    }
}

function getEsriGeom(restCall){

    //call ESRI Rest API
    //"http://pc302926/ArcGIS/rest/services/worldadmin/MapServer/0/query?text=&amp;geometry=&amp;geometryType=esriGeometryEnvelope&amp;inSR=&amp;spatialRel=esriSpatialRelIntersects&amp;where=%22FIPS_CNTRY%22+%3D+%27AS%27&amp;returnGeometry=true&amp;outSR=4326&amp;outFields=&amp;f=json"
    var element = document.getElementById('text');  

    //create esri JSON object
    var myReturn = "esriObj = "+xmlHttpGet(restCall, false);
    eval(myReturn);

    element.value = "";
    var coordPairsPerFeature = 0;

    //for each feature
    for (var i=0; i &lt; esriObj.features.length; i++)
    {
        //get the geometry
        var o = esriObj.features[i].geometry;
        element.value = element.value + esriObj.features[i].attributes.ADMIN_NAME;

        //loop through all the rings
        for (var s=0; s &lt; o.rings.length; s++)
        {
            //create geojson start &amp; end - i know i'm getting polygons
            var geojsonstart = '{"type":"Feature", "id":"OpenLayers.Feature.Vector_124", "properties":{}, "geometry":{"type":"Polygon", "coordinates":[['
            var geojsonend = ']]}, "crs":{"type":"OGC", "properties":{"urn":"urn:ogc:def:crs:OGC:1.3:CRS84"}}}';

            //the coordinates for this ring
            var coords = o.rings[s];

            //loop through each coordinate
            var coordPair="";
            for (var g=0; g &lt; coords.length; g++)
            {
                coordPairsPerFeature = coordPairsPerFeature+1;

                //alert(coords[g]);
                if(g==coords.length-1){
                    coordPair = coordPair+"["+coords[g]+"]";
                }else{
                    coordPair=coordPair+"["+coords[g]+"],";
                }
            }

            //combine to create geojson string
            esriDeserialize(geojsonstart+coordPair+geojsonend);
        }

        element.value = element.value + "," + coordPairsPerFeature +"n";
    }

}
</features.length;>

source: http://mapbutcher.com/blog/?p=62

Answer 3

Leaflet and ArGIS vector layer.

https://github.com/JasonSanford/leaflet-vector-layers

Working demo. http://geojason.info/leaflet-vector-layers/demos/arcgis-server/

More on Leaflet and ArcGIS.

• Leaflet and ArcGIS Server layers i.e. AgsDynamicLayer and AgsFeatureLayer.

You can get this fork which has support for ArcGIS server.

https://github.com/dtsagile/Leaflet/

 var sitesLayer = new L.AgsDynamicLayer(
    'http://ags2.dtsagile.com/ArcGIS/rest/services/LiveFeeds/WxMappr/MapServer',
    { maxZoom: 19,
        attribution: "NOAA",
        opacity: 1,
        layers: 'show:2' });
_map.addLayer(sitesLayer);

http://blog.davebouwman.com/2011/08/04/leaflet-lean-mean-javascript-maps/

ArcGIS Image Services and Leaflet http://blog.geomusings.com/2012/04/17/arcgis-image-services-and-leaflet/