Is there a way to save OpenLayers features to another file?

Question

I am utilizing two maps, one is where someone could add or remove features (admin file) and another that the end-users would see (user file). However, I have no way to save the features I added in my admin file upon refreshing in my browser.

I wanted to know if there's a way to save features and pull them up again (for both files)?

//the main map of the app
  var map = new ol.Map({
    target: 'map',
    layers: [
      new ol.layer.Tile({
        source: new ol.source.OSM()
      })
    ],
    view: new ol.View({
      center: ol.proj.fromLonLat([-90.055, 35.147]),
      zoom: 17,

    })
  });
//---------------------------------------------------------
//---------------------------------------------------------
///this creates the markers for the map

  var iconFeature = new ol.Feature({
    geometry: new ol.geom.Point(ol.proj.fromLonLat([-90.055, 35.147])),
    name: 'Somewhere else'
  });


  iconStyle = new ol.style.Style({
    image: new ol.style.Icon({
      anchor: [0.5, 46],
      anchorXUnits: 'fraction',
      anchorYUnits: 'pixels',
      src: 'icon.png',
    })
  });

  //Sets specific style for that one point
  iconFeature.setStyle(new ol.style.Style({
    image: new ol.style.Icon({
      anchor: [0.5, 46],
      anchorXUnits: 'fraction',
      anchorYUnits: 'pixels',
      src: 'icon.png',
    })
  }));

  eventFeature.setStyle(new ol.style.Style({
    image: new ol.style.Icon({
      anchor: [0.5, 46],
      anchorXUnits: 'fraction',
      anchorYUnits: 'pixels',
      src: 'icon.png',
    })
  }));

  var eventLayerSource = new ol.source.Vector({
    features: [iconFeature]
  });

//individual layers for the user to switch through based on selection
  var event_Layer = new ol.layer.Vector({
    source: eventLayerSource,
    // style for all elements on a layer
    style: new ol.style.Style({
      image: new ol.style.Icon({
        anchor: [0.5, 46],
        anchorXUnits: 'fraction',
        anchorYUnits: 'pixels',
        src: 'icon.png'
      })
    }),
    visible: true,
    tab_name: 'event'
  });

// display popup on click
  map.on('click', function (evt) {
    var coordinate = evt.coordinate;
    console.log(evt.coordinate);
    console.log(ol.proj.transform(evt.coordinate, 'EPSG:3857', 'EPSG:4326'));
  });

  map.on('singleclick', function (evt) {
    var lonLat = ol.proj.transform(evt.coordinate, 'EPSG:3857', 'EPSG:4326');
    var clickFeature = new ol.Feature({
      geometry: new ol.geom.Point(ol.proj.fromLonLat(lonLat)),
      name: window.prompt("Enter name of event","Event name"),
    });
    clickFeature.setStyle(iconStyle);
    clickFeature.setId(clickFeature.get('name'));
    eventLayerSource.addFeature(clickFeature);
  });
  map.on('dblclick', function(evt){
    eventLayerSource.removeFeature(
      eventLayerSource.getFeatureById(prompt("Enter name")));
  })

This is my code for the admin file. I appreciate any insight as I am new to Openlayers.

score 2 · Answer 1 · answered Apr 16 '21 at 09:51

You can save features you have drawn by writing them in a format such as GeoJSON or KML and then downloading them to the computer as a text file (just add buttons to your HTML to save/download)

  function download(data, filename) {
    var blob = new Blob([data], {type: 'text/plain'});
    if (navigator.msSaveBlob) {
      navigator.msSaveBlob(blob, filename);
    } else {
      var link = document.createElement('a');
      link.href = URL.createObjectURL(blob);
      link.download = filename;
      link.click();
    }
  }

  document.getElementById('download-geojson').addEventListener('click', function () {
    var text = new ol.format.GeoJSON().writeFeatures(
      source.getFeatures(),
      {
        featureProjection: 'EPSG:3857',
        dataProjection: 'EPSG:4326'
      }
    );
    download(text, 'features.json');
  });

  document.getElementById('download-kml').addEventListener('click', function () {
    var text = new ol.format.KML().writeFeatures(
      source.getFeatures(),
      {
        featureProjection: 'EPSG:3857',
        dataProjection: 'EPSG:4326'
      }
    );
    download(text, 'features.kml');
  });

The data in the files can be displayed again using Drag and Drop as in https://openlayers.org/en/latest/examples/drag-and-drop.html

Is there a way to save OpenLayers features to another file?

1 Answers1