======================

``GeoJSON`` Serializer

======================

.. module:: django.contrib.gis.serializers.geojson

    :synopsis: Serialization of GeoDjango models in the GeoJSON format.

GeoDjango provides a specific serializer for the `GeoJSON`__ format. See

:doc:`/topics/serialization` for more information on serialization.

__ https://geojson.org/

The ``geojson`` serializer is not meant for round-tripping data, as it has no

deserializer equivalent. For example, you cannot use :djadmin:`loaddata` to

reload the output produced by this serializer. If you plan to reload the

outputted data, use the plain :ref:`json serializer <serialization-formats-json>`

instead.

In addition to the options of the ``json`` serializer, the ``geojson``

serializer accepts the following additional option when it is called by

``serializers.serialize()``:

* ``geometry_field``: A string containing the name of a geometry field to use

  for the ``geometry`` key of the GeoJSON feature. This is only needed when you

  have a model with more than one geometry field and you don't want to use the

  first defined geometry field (by default, the first geometry field is picked).

* ``srid``: The SRID to use for the ``geometry`` content. Defaults to 4326

  (WGS 84).

The :ref:`fields <subset-of-fields>` option can be used to limit fields that

will be present in the ``properties`` key, as it works with all other

serializers.

Example::

    from django.core.serializers import serialize

    from my_app.models import City

    serialize('geojson', City.objects.all(),

              geometry_field='point',

              fields=('name',))

Would output::

    {

      'type': 'FeatureCollection',

      'crs': {

        'type': 'name',

        'properties': {'name': 'EPSG:4326'}

      },

      'features': [

        {

          'type': 'Feature',

          'geometry': {

            'type': 'Point',

            'coordinates': [-87.650175, 41.850385]

          },

          'properties': {

            'name': 'Chicago'

          }

        }

      ]

    }

When the ``fields`` parameter is not specified, the ``geojson`` serializer adds

a ``pk`` key to the ``properties`` dictionary with the primary key of the

object as the value.