Openlayers 3 + GeoJson özellikleri seçin

Question

Openlayers ve javascript’e yeni başladım. GeoJson'umu Openlayers projemde yükleyebilirim ama GeoJson dosyamın yalnızca bir özelliğini nasıl yazdıracağımı bilmiyorum. Benim GeoJSON ait

Örnek

{"type":"FeatureCollection","features":[ 
 
{"type":"Feature","id":"AFG","properties":{"name":"Afghanistan"},"geometry":{"type":"Polygon","coordinates":[[[61.210817,35.650072],[62.230651,35.270664],[62.984662,35.404041],[63.193538,35.857166],[63.982896,36.007957],[64.546479,36.312073],[64.746105,37.111818],[65.588948,37.305217],[65.745631,37.661164],[66.217385,37.39379],[66.518607,37.362784],[67.075782,37.356144],[67.83,37.144994],[68.135562,37.023115],[68.859446,37.344336],[69.196273,37.151144],[69.518785,37.608997],[70.116578,37.588223],[70.270574,37.735165],[70.376304,38.138396],[70.806821,38.486282],[71.348131,38.258905],[71.239404,37.953265],[71.541918,37.905774],[71.448693,37.065645],[71.844638,36.738171],[72.193041,36.948288],[72.63689,37.047558],[73.260056,37.495257],[73.948696,37.421566],[74.980002,37.41999],[75.158028,37.133031],[74.575893,37.020841],[74.067552,36.836176],[72.920025,36.720007],[71.846292,36.509942],[71.262348,36.074388],[71.498768,35.650563],[71.613076,35.153203],[71.115019,34.733126],[71.156773,34.348911],[70.881803,33.988856],[69.930543,34.02012],[70.323594,33.358533],[69.687147,33.105499],[69.262522,32.501944],[69.317764,31.901412],[68.926677,31.620189],[68.556932,31.71331],[67.792689,31.58293],[67.683394,31.303154],[66.938891,31.304911],[66.381458,30.738899],[66.346473,29.887943],[65.046862,29.472181],[64.350419,29.560031],[64.148002,29.340819],[63.550261,29.468331],[62.549857,29.318572],[60.874248,29.829239],[61.781222,30.73585],[61.699314,31.379506],[60.941945,31.548075],[60.863655,32.18292],[60.536078,32.981269],[60.9637,33.528832],[60.52843,33.676446],[60.803193,34.404102],[61.210817,35.650072]]]}}, 
 
{"type":"Feature","id":"AGO","properties":{"name":"Angola"},"geometry":{"type":"MultiPolygon","coordinates":[[[[16.326528,-5.87747],[16.57318,-6.622645],[16.860191,-7.222298],[17.089996,-7.545689],[17.47297,-8.068551],[18.134222,-7.987678],[18.464176,-7.847014],[19.016752,-7.988246],[19.166613,-7.738184],[19.417502,-7.155429],[20.037723,-7.116361],[20.091622,-6.94309],[20.601823,-6.939318],[20.514748,-7.299606],[21.728111,-7.290872],[21.746456,-7.920085],[21.949131,-8.305901],[21.801801,-8.908707],[21.875182,-9.523708],[22.208753,-9.894796],[22.155268,-11.084801],[22.402798,-10.993075],[22.837345,-11.017622],[23.456791,-10.867863],[23.912215,-10.926826],[24.017894,-11.237298],[23.904154,-11.722282],[24.079905,-12.191297],[23.930922,-12.565848],[24.016137,-12.911046],[21.933886,-12.898437],[21.887843,-16.08031],[22.562478,-16.898451],[23.215048,-17.523116],[21.377176,-17.930636],[18.956187,-17.789095],[18.263309,-17.309951],[14.209707,-17.353101],[14.058501,-17.423381],[13.462362,-16.971212],[12.814081,-16.941343],[12.215461,-17.111668],[11.734199,-17.301889],[11.640096,-16.673142],[11.778537,-15.793816],[12.123581,-14.878316],[12.175619,-14.449144],[12.500095,-13.5477],[12.738479,-13.137906],[13.312914,-12.48363],[13.633721,-12.038645],[13.738728,-11.297863],[13.686379,-10.731076],[13.387328,-10.373578],[13.120988,-9.766897],[12.87537,-9.166934],[12.929061,-8.959091],[13.236433,-8.562629],[12.93304,-7.596539],[12.728298,-6.927122],[12.227347,-6.294448],[12.322432,-6.100092],[12.735171,-5.965682],[13.024869,-5.984389],[13.375597,-5.864241],[16.326528,-5.87747]]],[[[12.436688,-5.684304],[12.182337,-5.789931],[11.914963,-5.037987],[12.318608,-4.60623],[12.62076,-4.438023],[12.995517,-4.781103],[12.631612,-4.991271],[12.468004,-5.248362],[12.436688,-5.684304]]]]}}, 
 
{"type":"Feature","id":"ALB","properties":{"name":"Albania"},"geometry":{"type":"Polygon","coordinates":[[[20.590247,41.855404],[20.463175,41.515089],[20.605182,41.086226],[21.02004,40.842727],[20.99999,40.580004],[20.674997,40.435],[20.615,40.110007],[20.150016,39.624998],[19.98,39.694993],[19.960002,39.915006],[19.406082,40.250773],[19.319059,40.72723],[19.40355,41.409566],[19.540027,41.719986],[19.371769,41.877548],[19.304486,42.195745],[19.738051,42.688247],[19.801613,42.500093],[20.0707,42.58863],[20.283755,42.32026],[20.52295,42.21787],[20.590247,41.855404]]]}}, 
 
]}

Ben

var countries = new ol.layer.Vector({ 
 
    source: new ol.source.Vector({ 
 
    url: '../countries/countries.geo.json', 
 
    format: new ol.format.GeoJSON() 
 
    }), 
 
    style: function(feature, resolution) { 
 
    style.getText().setText(resolution < 10000 ? feature.get('name') : ''); 
 
    return style; 
 
    } 
 
}); 
 

 
map.addLayer(countries);

Şimdi, sadece Angola'yı yazdırabilirsiniz nasıl katman yüklediğinizde haritamda?

Teşekkür

Answer 1

Belki bu size yardımcı olabilecek bir sürü:

var geoJSONFormat = new ol.format.GeoJSON(); 

var vectorSource = new ol.source.Vector({ 
    loader: function(extent, resolution, projection) { 
    var url = '../countries/countries.geo.json'; 
    $.ajax({ 
     url: url, 
     success: function(data) { 
     // here, parse the data and delete all unwanted features 
     var features = geoJSONFormat.readFeatures(data); 
     // keep only the features that you want in the array 
     var subset = []; 
     var names = ['Angola'] 
     features.forEach(function(feature) { 
      if (names.indexOf(feature.get('name') !== -1) { 
      subset.push(feature); 
      } 
     }, this); 

     vectorSource.addFeatures(subset); 
     } 
    }); 
    } 
});