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jsonsql-serveropenlayersopenlayers-3wkt

how to get all information of wkt polygon when i click on it?

I get the data from MSsql server 2012 in json format, i get just WKT string to convert for showing on the map using ol.format.WKT() .

I want to show the ID and the name of the polygon when i click, on popup. How can i recognize in which polygon am i clicking?

How can i know the map in which polygon I click and get me the data of that polygon?

for (var i = 0; i < geometries.length; i++) {

    var feature = wktReader.readFeature(geometries[i].GeomCol1.Geometry.WellKnownText);

    feature.getGeometry().transform('EPSG:4326', 'EPSG:3857');

    if (feature.getGeometry().getType() == 'Polygon') {
        feature.setStyle(new ol.style.Style({
            stroke: new ol.style.Stroke({
                color: 'blue',
                width: 1
            }),
            fill: new ol.style.Fill({
                color: 'rgba(0, 0, 255, 0.1)'
            })
       }));
       featureCollection.push(feature);
    }
}

this is a part how i get just wkt string.

These are the polygons that i have shown, and i want to show a popup with the informations of the polygon which i click These are the polygons that i have shown, and i want to show a popup with the informations of the polygon which i click

This is a picture of how i have stored the spatial data in my MSsql server

This is a picture of how i have stored the spatial data in my MSsql server

Thanks

Solution

  • forEachFeatureAtPixel (api doc) can get you all the features on a certain position. Admittedly, it can be confusing to use. The callback you pass to that function is called for every layer. If the callback returns a truthy value, it stops and then forEachFeatureAtPixel returns whatever your callback returned. This makes it perfect to select a specific feature.

    var count = 2000;
var features = new Array(count);
var e = 4500000;
for (var i = 0; i < count; ++i) {
  var coordinates = [2 * e * Math.random() - e, 2 * e * Math.random() - e];
  features[i] = new ol.Feature({
    geometry: new ol.geom.Point(coordinates),
    myHappyAttribute: ('you are beautiful ' + i)
  });
}

var source = new ol.source.Vector({
  features: features
});

var layer = new ol.layer.Vector({source: source});


const view = new ol.View({
  center: [2500000, 0], zoom: 5
});
const map = new ol.Map({
  layers: [ 
    new ol.layer.Tile({
        source: new ol.source.OSM()
    }),
    layer
  ],
  target: 'map',
  view 
});


map.on('singleclick', function(evt) {
  const pixel = map.getEventPixel(evt.originalEvent);
  const feature = map.forEachFeatureAtPixel(
    pixel,
    someFeature => someFeature, // return first element
    {
      hitTolerance: 2 // how far off the click can be
    }
  );
  if (feature) {
    const attr = feature.get('myHappyAttribute');
    console.log('clicked on feature with attr:', attr);
  } else {
    console.log('not clicked on a feature');
  }
});
    <link href="https://openlayers.org/en/v4.6.5/css/ol.css" rel="stylesheet"/>
<script src="https://openlayers.org/en/v4.6.5/build/ol-debug.js"></script>
<div id="map" class="map"></div>