OpenLayers 读/写 GeoJSON

Question

i try to store features of a OpenLayers Map Layer to a database and therefore I try to write the features objects into a GeoJSON object. But I get an Unsupported GeoJSON type: undefined error when I try to read the object. Here what i tried:

       const testFeature = new Feature({
          geometry: new Point([0, 0]),
          name: 'Test Point '
        });
        const geoJsonObject = new GeoJSON();
        geoJsonObject.writeFeaturesObject(testFeature);
        console.log(geoJsonObject);

        const importObject = new GeoJSON().readFeatures(geoJsonObject);
        console.log(importObject);

The first log of the "geoJsonObject":

{
  "dataProjection": {
    "code_": "EPSG:4326",
    "units_": "degrees",
    "extent_": [
      -180,
      -90,
      180,
      90
    ],
    "worldExtent_": [
      -180,
      -90,
      180,
      90
    ],
    "axisOrientation_": "neu",
    "global_": true,
    "canWrapX_": true,
    "defaultTileGrid_": null,
    "metersPerUnit_": 111319.49079327358
  },
  "defaultFeatureProjection": null
}

Here the error from the log of the importObject:

Unsupported GeoJSON type: undefined

OpenLayers Version: 6.2.1 Docs: https://openlayers.org/en/latest/apidoc/module-ol_format_GeoJSON-GeoJSON.html#writeFeature

Thanks!

Answer 1

As well as needing an array of features with writeFeaturesObject your use of geoJsonObject was wrong

const geoJsonObject = new GeoJSON().writeFeaturesObject([testFeature]);
console.log(geoJsonObject);

const importObject = new GeoJSON().readFeatures(geoJsonObject);
console.log(importObject);