django/tests/gis_tests/geoapp/test_serializers.py

from __future__ import unicode_literals

import json

from django.contrib.gis.geos import LinearRing, Point, Polygon
from django.core import serializers
from django.test import TestCase, mock, skipUnlessDBFeature
from django.utils import six

from .models import City, MultiFields, PennsylvaniaCity


@skipUnlessDBFeature("gis_enabled")
class GeoJSONSerializerTests(TestCase):
    fixtures = ['initial']

    def test_builtin_serializers(self):
        """
        'geojson' should be listed in available serializers.
        """
        all_formats = set(serializers.get_serializer_formats())
        public_formats = set(serializers.get_public_serializer_formats())

        self.assertIn('geojson', all_formats),
        self.assertIn('geojson', public_formats)

    def test_serialization_base(self):
        geojson = serializers.serialize('geojson', City.objects.all().order_by('name'))
        try:
            geodata = json.loads(geojson)
        except Exception:
            self.fail("Serialized output is not valid JSON")
        self.assertEqual(len(geodata['features']), len(City.objects.all()))
        self.assertEqual(geodata['features'][0]['geometry']['type'], 'Point')
        self.assertEqual(geodata['features'][0]['properties']['name'], 'Chicago')

    def test_geometry_field_option(self):
        """
        When a model has several geometry fields, the 'geometry_field' option
        can be used to specify the field to use as the 'geometry' key.
        """
        MultiFields.objects.create(
            city=City.objects.first(), name='Name', point=Point(5, 23),
            poly=Polygon(LinearRing((0, 0), (0, 5), (5, 5), (5, 0), (0, 0))))

        geojson = serializers.serialize('geojson', MultiFields.objects.all())
        geodata = json.loads(geojson)
        self.assertEqual(geodata['features'][0]['geometry']['type'], 'Point')

        geojson = serializers.serialize(
            'geojson',
            MultiFields.objects.all(),
            geometry_field='poly'
        )
        geodata = json.loads(geojson)
        self.assertEqual(geodata['features'][0]['geometry']['type'], 'Polygon')

        # geometry_field is considered even if not in fields (#26138).
        geojson = serializers.serialize(
            'geojson',
            MultiFields.objects.all(),
            geometry_field='poly',
            fields=('city',)
        )
        geodata = json.loads(geojson)
        self.assertEqual(geodata['features'][0]['geometry']['type'], 'Polygon')

    def test_fields_option(self):
        """
        The fields option allows to define a subset of fields to be present in
        the 'properties' of the generated output.
        """
        PennsylvaniaCity.objects.create(name='Mansfield', county='Tioga', point='POINT(-77.071445 41.823881)')
        geojson = serializers.serialize('geojson', PennsylvaniaCity.objects.all(),
            fields=('county', 'point'))
        geodata = json.loads(geojson)
        self.assertIn('county', geodata['features'][0]['properties'])
        self.assertNotIn('founded', geodata['features'][0]['properties'])

    def test_srid_option(self):
        geojson = serializers.serialize('geojson', City.objects.all().order_by('name'), srid=2847)
        geodata = json.loads(geojson)
        self.assertEqual(
            [int(c) for c in geodata['features'][0]['geometry']['coordinates']],
            [1564802, 5613214])

    @mock.patch('django.contrib.gis.serializers.geojson.HAS_GDAL', False)
    def test_without_gdal(self):
        # Without coordinate transformation, the serialization should succeed:
        serializers.serialize('geojson', City.objects.all())
        with six.assertRaisesRegex(self, serializers.base.SerializationError, '.*GDAL is not installed'):
            # Coordinate transformations need GDAL
            serializers.serialize('geojson', City.objects.all(), srid=2847)

    def test_deserialization_exception(self):
        """
        GeoJSON cannot be deserialized.
        """
        with self.assertRaises(serializers.base.SerializerDoesNotExist):
            serializers.deserialize('geojson', '{}')