CODEWITHSUNDEEP
djangojsonopenlayersgeodjangogeojson
iamjoanel
iamjoanel

Reputation: 25

Django + Openlayers GeoJSON not displaying

I'm having trouble displaying features from my django server to a vector layer on openlayers, I've already referenced these articles:

Rendering spatial data of GeoQuerySet in a custom view on GeoDjango

https://gis.stackexchange.com/questions/22529/trouble-displaying-geojson-file-in-openlayers?rq=1

but still can't make it show.

so here is the javascript block:

  function init(){
      var map = new OpenLayers.Map('map', {
      projection: new OpenLayers.Projection("EPSG:3857"),
      units: "km",
      maxResolution: 156543.0339,
      displayProjection: new OpenLayers.Projection("EPSG:4326"),
      controls: [
        new OpenLayers.Control.Navigation(),
        new OpenLayers.Control.KeyboardDefaults(),
        new OpenLayers.Control.PanZoomBar(),
        new OpenLayers.Control.Scale(),
        new OpenLayers.Control.Attribution()
      ]
    });

    var osm_layer = new OpenLayers.Layer.OSM("OpenStreetMap");
    map.addLayer(osm_layer);

    var vector_style = new OpenLayers.Style({
      strokeWidth:2,
      fillOpacity:0,
      strokeColor: '#008000'
    });

    var vector_style_map = new OpenLayers.StyleMap({
         'default': vector_style,
         'select': {strokeColor: '#0000FF'}
    });

    var path_layer = new OpenLayers.Layer.Vector("Path Layer", {
      protocol: new OpenLayers.Protocol.HTTP({
        url: "{% url 'get_path_json' route.id %}",
        format: new OpenLayers.Format.GeoJSON({
          internalProjection: new OpenLayers.Projection("EPSG:3857"),
          externalProjection: new OpenLayers.Projection("EPSG:4326")})
      }),
      strategies: [new OpenLayers.Strategy.Fixed()],
      styleMap: vector_style_map
    });

    map.addLayer(path_layer);

    map.addControl(new OpenLayers.Control.LayerSwitcher());
    map.setCenter(
    new OpenLayers.LonLat(121.032, 14.594).transform(new OpenLayers.Projection("EPSG:4326"), map.getProjectionObject()), 12);
    if(!map.getCenter()){
      map.zoomToMaxExtent();
    }
  }

and here are my views that call the GeoJSON object:

def get_path_json(request, route_id):
    route = get_object_or_404(Route, pk=route_id)
    geoj = GeoJSON.GeoJSON()
    path = route.path.all()

    path_format = Django.Django(geodjango="path")
    path_json = geoj.encode(path_format.decode(path))

    return HttpResponse(path_json, content_type="application/json")

and upon checking on firebug, there the json was requested:

enter image description here Am i missing something? cause it still doesn't show the objects on the map.

Upvotes: 0

Views: 742

Answers (2)

jcs
jcs

Reputation: 436

If your vector layer is loaded but not displayed it is probably a projection problem.

I would gess that OSM's EPSG is not 4326 but 900913 !

Upvotes: 1

Christiano Anderson
Christiano Anderson

Reputation: 81

Make sure the path_json is not broken. If you have more than one item, it should be a featured collection.

Upvotes: 0

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