GeoDjango serialize GeoJSON skipping 'id' field

问题

I've been using the Geo-Django GeoJSON serializer so that I can retrieve some objects from a PostGIS database and display them on an OpenLayers map.

I'm obtaining the objects for display in the following way:

gqs = self.model.objects.filter(point__distance_lte=(pnt, long(dist)))
type(gqs)
<class 'django.contrib.gis.db.models.query.GeoQuerySet'>

and the Geo-Objects include all the model fields as expected:

self.model._meta.get_fields()
(<django.db.models.fields.AutoField: id>,
<django.db.models.fields.CharField: name>, 
<django.db.models.fields.SlugField: name_slug>, 
<django.db.models.fields.CharField: contact>, 
<django.db.models.fields.CharField: address>, 
<django.db.models.fields.CharField: postcode>, 
<django.db.models.fields.EmailField: email>, 
<django.db.models.fields.CharField: fax>, 
<django.db.models.fields.CharField: tel>, 
<django.db.models.fields.CharField: tel1>, 
<django.db.models.fields.CharField: tel_fax>, 
<django.db.models.fields.URLField: url>, 
<django.db.models.fields.CharField: wardlabel>, 
<django.db.models.fields.DecimalField: lon>, 
<django.db.models.fields.DecimalField: lat>, 
<django.db.models.fields.IntegerField: easting>, 
<django.db.models.fields.IntegerField: northing>, 
<django.db.models.fields.DateField: first_entered>, 
<django.db.models.fields.DateField: updated>, 
<django.contrib.gis.db.models.fields.PointField: point>)

Including the id value...

(Pdb) gqs[0].id
5

I then pass the GeoQuerySet to the GeoJSON serializer in the simplest possible way:

gqs_serialized = serialize('geojson', gqs)

and get output:

gqs_serialized
u'{"type": "FeatureCollection", 
  "crs": {
    "type": "name", 
    "properties": {"name": "EPSG:4326"}}, 
    "features": [
    {"geometry": {"type": "Point", "coordinates": [-0.19038, 51.490657]}, "type": "Feature", 
    "properties": {
      "tel1": null, 
      "fax": null, 
      "tel": null, 
      "name": "some club", 
      "url": null, 
      "wardlabel": "Redcliffe", 
      "lon": "-0.190380", 
      "updated": null, 
      "first_entered": "2013-12-01", 
      "contact": "some name", 
      "name_slug": "some club slug", 
      "postcode": "SW5 0JE", 
      "easting": 525732, 
      "address": "Some Address, London", 
      "lat": "51.490657", 
      "tel_fax": null, 
      "email": null, 
      "northing": 178409}},
     {"geometry": {"type": "Point", "coordinates": [-0.137183, 51.495597]}, "type": "Feature", 
    "properties": { etc...

Everything is present but the 'id' field (AutoField) from the model. I want to use the id values as div id values in a webpage and I don't really want to have to create another unique id (ie. combining lon/lat values) when I think one should already be available.

What happened to the missing 'id' field?

回答1:

As far as the output must be compatible with the specs, the stock serializer omits unsupported fields. However, you could craft your own serializer:

# yourapp/geojson_serializer.py
from django.contrib.gis.serializers import Serializer as GeoJSONSerializer

class Serializer(GeoJSONSerializer):
    def get_dump_object(self, obj):
        data = super(Serializer, self).get_dump_object(obj)
        # Extend to your taste
        data.update(id=obj.pk)
        return data

Enable your new serializer in settings.py:

SERIALIZATION_MODULES = {
        "custom_geojson": "yourapp.geojson_serializer",
}

And then use it in your code:

from django.core import serializers
data = serializers.serialize('custom_geojson', some_model)

回答2:

I was able to solve this as well by using the input from @jayuu . For new readers interested in this issue I post the complete solution:

#myapp/geojson_serializer.py
from django.core import serializers

GeoJSONSerializer = serializers.get_serializer("geojson")

class Serializer(GeoJSONSerializer):
    def get_dump_object(self, obj):
        data = super(Serializer, self).get_dump_object(obj)
        # Extend to your taste
        data.update(id=obj.pk)
        return data

Then, to use it in my views I just imported the function because I had no interest in registering my serializer

#myapp/views.py
from .geojson_serializer import Serializer

def MapDataView(request):
    geojson_serializer = Serializer()
    geojson_serializer.serialize(some_queryset)
    data = geojson_serializer.getvalue()
    return HttpResponse(data, content_type='json')

And there you have it.

回答3:

One way I solved this was asking it to serialize the "pk" field, which worked as expected.

gqs_serialized = serialize('geojson', gqs, fields=('pk', ))

来源：https://stackoverflow.com/questions/34556679/geodjango-serialize-geojson-skipping-id-field

标签

django

serialization

geojson

geodjango