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82 lines
2.6 KiB
Plaintext
82 lines
2.6 KiB
Plaintext
======================
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``GeoJSON`` Serializer
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======================
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.. module:: django.contrib.gis.serializers.geojson
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:synopsis: Serialization of GeoDjango models in the GeoJSON format.
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GeoDjango provides a specific serializer for the `GeoJSON`__ format. See
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:doc:`/topics/serialization` for more information on serialization.
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The GDAL library is required if any of the serialized geometries need
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coordinate transformations (that is if the geometry's spatial reference system
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differs from the ``srid`` serializer option).
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.. versionchanged:: 1.9
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The GeoJSON serializer no longer needs GDAL if all geometries are in the
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same coordinate system as the ``srid`` serializer option.
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__ http://geojson.org/
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The ``geojson`` serializer is not meant for round-tripping data, as it has no
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deserializer equivalent. For example, you cannot use :djadmin:`loaddata` to
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reload the output produced by this serializer. If you plan to reload the
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outputted data, use the plain :ref:`json serializer <serialization-formats-json>`
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instead.
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In addition to the options of the ``json`` serializer, the ``geojson``
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serializer accepts the following additional option when it is called by
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``serializers.serialize()``:
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* ``geometry_field``: A string containing the name of a geometry field to use
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for the ``geometry`` key of the GeoJSON feature. This is only needed when you
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have a model with more than one geometry field and you don't want to use the
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first defined geometry field (by default, the first geometry field is picked).
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* ``srid``: The SRID to use for the ``geometry`` content. Defaults to 4326
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(WGS 84).
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The :ref:`fields <subset-of-fields>` option can be used to limit fields that
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will be present in the ``properties`` key, as it works with all other
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serializers.
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Example::
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from django.core.serializers import serialize
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from my_app.models import City
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serialize('geojson', City.objects.all(),
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geometry_field='point',
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fields=('name',))
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Would output::
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{
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'type': 'FeatureCollection',
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'crs': {
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'type': 'name',
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'properties': {'name': 'EPSG:4326'}
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},
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'features': [
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{
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'type': 'Feature',
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'geometry': {
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'type': 'Point',
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'coordinates': [-87.650175, 41.850385]
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},
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'properties': {
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'name': 'Chicago'
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}
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}
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]
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}
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When the ``fields`` parameter is not specified, the ``geojson`` serializer adds
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a ``pk`` key to the ``properties`` dictionary with the primary key of the
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object as the value.
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.. versionchanged:: 1.10
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The ``pk`` key was added to the ``properties`` dictionary.
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