从 Openlayers 功能读取 GeoJSON 键和值

Question

我正在使用 OpenLayers 在地图上创建、显示和编辑要素。特性在 Django 中保存为 JSONField。保存后我将密钥 django_pk 添加到 JSON。如何直接从功能中获取此 djanog_pk？

我需要这样做，以便在编辑功能时，我知道要在 Django 中更新什么功能。

我的JS代码如下：

<script>
      var raster = new ol.layer.Tile({
        source: new ol.source.OSM()
      });

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

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

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

      var select = new ol.interaction.Select({
        wrapX: false
      });

      var modify = new ol.interaction.Modify({
        features: select.getFeatures()
      });



      var map = new ol.Map({
        interactions: ol.interaction.defaults().extend([select, modify]),
        layers: [raster, vector],
        target: 'map',
        view: new ol.View({
          center: [-11000000, 4600000],
          zoom: 4
        })
      });

      var features = new ol.source.Vector({
          projection: 'EPSG:4326'
      });

      {% for polygon in polygons.0.gates %}
        console.log(format.readFeature({{ polygon|safe }}).getProperties()))
      {% endfor %}

      features.addFeature(format.readFeature({{ polygons.0.protected_area|safe }}));
      {% for polygon in polygons.0.gates %}
        features.addFeature(format.readFeature({{ polygon|safe }}));
        console.log(format.readFeature({{ polygon|safe }}))
      {% endfor %}

      var featureOverlay = new ol.layer.Vector({
        source: features,
        style: new ol.style.Style({
          fill: new ol.style.Fill({
            color: 'rgba(255, 255, 255, 0.2)'
          }),
          stroke: new ol.style.Stroke({
            color: '#ff78d1',
            width: 2
          }),
          image: new ol.style.Circle({
            radius: 6,
            fill: new ol.style.Fill({
              color: '#4ca6b6'
            }),
          })
        })
      });
      featureOverlay.setMap(map);


</script>

我试过这个：Buyt it only return geometry:

select.on('select', function(e) { console.log(e.selected[0].getProperties()) });

Django 中的 JSONField 如下所示：

{
  "geometry":{
    "type":"Polygon",
    "coordinates":[
      [
        [
          -11156543.033928039,
          6698655.0485978
        ],
        [
          -11410925.464061106,
          5896371.999716589
        ],
        [
          -9972686.33984723,
          5084305.011214877
        ],
        [
          -9512841.177683609,
          6649735.350495286
        ],
        [
          -10090093.61529326,
          6972605.357971871
        ],
        [
          -11156543.033928039,
          6698655.0485978
        ]
      ]
    ]
  },
  "type":"Feature",
  "properties":null,
  "django_pk":10
}

所以我需要在编辑它时找到 django_pk 的功能，它选择它，而不是删除它。

不确定如何获取此信息

Answer 1

好的，我其实很简单。

您可以读取 GeoJSON 格式的任何属性：

select.on('select', function(e) {
   console.log(e.selected[0].getProperties())
});

选择存在：

var select = new ol.interaction.Select({
        wrapX: false
      });

在我的 Django 代码中，我只是在 post_save 上执行此操作：

@receiver(post_save, sender=ProtectedArea)
def update_json(sender, instance, created, **kwargs):
    post_save.disconnect(update_json, sender=ProtectedArea)
    try:
        instance.polygone = literal_eval("%s" % instance.geojson_file.read())
    except:
        pass

    if instance.polygone['properties'] == None:
        instance.polygone['properties'] = {}
        instance.polygone['properties']['pk'] = instance.pk
    else:   
        instance.polygone['properties']['pk'] = instance.pk
    instance.save()
    post_save.connect(update_json, sender=ProtectedArea)