Currently in OpenLayers, I am creating features from a GeoJSON FeatureCollection as follows:

const points = JSON.parse(document.getElementById('points-data').textContent);
const features = new ol.format.GeoJSON().readFeatures(
    {featureProjection: "EPSG:3857",}

This all works fine normally, but breaks an OpenLayers extension I'm trying to use called GridBin at a step that tries to get the geometry of the feature sources passed to it. This is what a GridBin layer constructor looks like:

    var countingGrid = new ol.layer.Vector({
        style: gridCount,
        source: new ol.source.GridBin({
            source: source,

From what I can tell in the documentation, objects created via the GeoJSON().readFeatures() method is slightly different to standard ol.geom.Point objects, in that the coordinates are not retrievable from a getter function for geojson features unlike geom Point features. I'm sorry if this is confusing, I'm still trying to work out the OpenLayers API. The solution I think would be to somehow add a geometry to, or fetch the geometry from, the features created from GeoJSON, how do I achieve this? Below is the console error trace for reference.

ol.js:8 Uncaught TypeError: Cannot read property 'getCode' of null
    at Zr (ol.js:8)
    at Kr (ol.js:8)
    at Object.Hr [as transform] (ol.js:8)
    at ol.source.GridBin.getGridGeomAt (ol-ext.js:19900)
    at ol.source.GridBin.ol.source.BinBase.getBinAt (ol-ext.js:18390)
    at ol.source.GridBin.ol.source.BinBase._onAddFeature (ol-ext.js:18311)
    at ol.source.GridBin.ol.source.BinBase.reset (ol-ext.js:18430)
    at ol.source.GridBin.ol.source.BinBase [as constructor] (ol-ext.js:18294)
    at new ol.source.GridBin (ol-ext.js:19875)
    at displayDateRange (main.js:431)

My suspicion is that it breaks where it tries getGridGeomAt, since the features I'm using are not geom objects, it returns null.

  • transform and getCode suggest a projection is expected but not correctly defined.
    – Mike
    Commented Jul 21, 2021 at 15:13
  • Also if the geometry may not be Point you will need a geometry function to return a Point geometry from LineStrings, Polygons, etc. viglino.github.io/ol-ext/doc/doc-pages/ol.source.GridBin.html
    – Mike
    Commented Jul 21, 2021 at 15:21
  • @Mike Thank you for responding! Do you have any idea where the projection might be expected? I've looked at the doc page, and I've tried creating a new set of ol.geom.Point objects using the coordinates from the geosjon collection but it still returns the same error. Commented Jul 21, 2021 at 15:36

1 Answer 1


I've gotten it working, I had to create an empty source object, set it as the source of the grid layer, and then populate the source with features afterwards. I have no idea why this fixes it, if anyone has any idea please explain, it would be very appreciated!

var source = new ol.source.Vector();
var featuresList = [] //populated in whatever way
var grid = new ol.layer.Vector({
    style: styleFn,
    source: new ol.source.GridBin({
        source: source;

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