django/tests/gis_tests/geogapp/tests.py

"""
Tests for geography support in PostGIS
"""
import os
from unittest import skipIf, skipUnless

from django.contrib.gis.db import models
from django.contrib.gis.db.models.functions import Area, Distance
from django.contrib.gis.measure import D
from django.db import connection
from django.db.models.functions import Cast
from django.test import TestCase, skipIfDBFeature, skipUnlessDBFeature

from ..utils import oracle, postgis, spatialite
from .models import City, County, Zipcode


class GeographyTest(TestCase):
    fixtures = ['initial']

    def test01_fixture_load(self):
        "Ensure geography features loaded properly."
        self.assertEqual(8, City.objects.count())

    @skipIf(spatialite, "SpatiaLite doesn't support distance lookups with Distance objects.")
    @skipUnlessDBFeature("supports_distances_lookups", "supports_distance_geodetic")
    def test02_distance_lookup(self):
        "Testing distance lookup support on non-point geography fields."
        z = Zipcode.objects.get(code='77002')
        cities1 = list(City.objects
                       .filter(point__distance_lte=(z.poly, D(mi=500)))
                       .order_by('name')
                       .values_list('name', flat=True))
        cities2 = list(City.objects
                       .filter(point__dwithin=(z.poly, D(mi=500)))
                       .order_by('name')
                       .values_list('name', flat=True))
        for cities in [cities1, cities2]:
            self.assertEqual(['Dallas', 'Houston', 'Oklahoma City'], cities)

    @skipUnless(postgis, "This is a PostGIS-specific test")
    def test04_invalid_operators_functions(self):
        "Ensuring exceptions are raised for operators & functions invalid on geography fields."
        # Only a subset of the geometry functions & operator are available
        # to PostGIS geography types.  For more information, visit:
        # http://postgis.refractions.net/documentation/manual-1.5/ch08.html#PostGIS_GeographyFunctions
        z = Zipcode.objects.get(code='77002')
        # ST_Within not available.
        with self.assertRaises(ValueError):
            City.objects.filter(point__within=z.poly).count()
        # `@` operator not available.
        with self.assertRaises(ValueError):
            City.objects.filter(point__contained=z.poly).count()

        # Regression test for #14060, `~=` was never really implemented for PostGIS.
        htown = City.objects.get(name='Houston')
        with self.assertRaises(ValueError):
            City.objects.get(point__exact=htown.point)

    def test05_geography_layermapping(self):
        "Testing LayerMapping support on models with geography fields."
        # There is a similar test in `layermap` that uses the same data set,
        # but the County model here is a bit different.
        from django.contrib.gis.utils import LayerMapping

        # Getting the shapefile and mapping dictionary.
        shp_path = os.path.realpath(os.path.join(os.path.dirname(__file__), '..', 'data'))
        co_shp = os.path.join(shp_path, 'counties', 'counties.shp')
        co_mapping = {'name': 'Name',
                      'state': 'State',
                      'mpoly': 'MULTIPOLYGON',
                      }

        # Reference county names, number of polygons, and state names.
        names = ['Bexar', 'Galveston', 'Harris', 'Honolulu', 'Pueblo']
        num_polys = [1, 2, 1, 19, 1]  # Number of polygons for each.
        st_names = ['Texas', 'Texas', 'Texas', 'Hawaii', 'Colorado']

        lm = LayerMapping(County, co_shp, co_mapping, source_srs=4269, unique='name')
        lm.save(silent=True, strict=True)

        for c, name, num_poly, state in zip(County.objects.order_by('name'), names, num_polys, st_names):
            self.assertEqual(4326, c.mpoly.srid)
            self.assertEqual(num_poly, len(c.mpoly))
            self.assertEqual(name, c.name)
            self.assertEqual(state, c.state)


class GeographyFunctionTests(TestCase):
    fixtures = ['initial']

    @skipUnlessDBFeature("supports_extent_aggr")
    def test_cast_aggregate(self):
        """
        Cast a geography to a geometry field for an aggregate function that
        expects a geometry input.
        """
        if not connection.ops.geography:
            self.skipTest("This test needs geography support")
        expected = (-96.8016128540039, 29.7633724212646, -95.3631439208984, 32.782058715820)
        res = City.objects.filter(
            name__in=('Houston', 'Dallas')
        ).aggregate(extent=models.Extent(Cast('point', models.PointField())))
        for val, exp in zip(res['extent'], expected):
            self.assertAlmostEqual(exp, val, 4)

    @skipUnlessDBFeature("has_Distance_function", "supports_distance_geodetic")
    def test_distance_function(self):
        """
        Testing Distance() support on non-point geography fields.
        """
        if oracle:
            ref_dists = [0, 4899.68, 8081.30, 9115.15]
        elif spatialite:
            # SpatiaLite returns non-zero distance for polygons and points
            # covered by that polygon.
            ref_dists = [326.61, 4899.68, 8081.30, 9115.15]
        else:
            ref_dists = [0, 4891.20, 8071.64, 9123.95]
        htown = City.objects.get(name='Houston')
        qs = Zipcode.objects.annotate(
            distance=Distance('poly', htown.point),
            distance2=Distance(htown.point, 'poly'),
        )
        for z, ref in zip(qs, ref_dists):
            self.assertAlmostEqual(z.distance.m, ref, 2)

        if postgis:
            # PostGIS casts geography to geometry when distance2 is calculated.
            ref_dists = [0, 4899.68, 8081.30, 9115.15]
        for z, ref in zip(qs, ref_dists):
            self.assertAlmostEqual(z.distance2.m, ref, 2)

        if not spatialite:
            # Distance function combined with a lookup.
            hzip = Zipcode.objects.get(code='77002')
            self.assertEqual(qs.get(distance__lte=0), hzip)

    @skipUnlessDBFeature("has_Area_function", "supports_area_geodetic")
    def test_geography_area(self):
        """
        Testing that Area calculations work on geography columns.
        """
        # SELECT ST_Area(poly) FROM geogapp_zipcode WHERE code='77002';
        z = Zipcode.objects.annotate(area=Area('poly')).get(code='77002')
        # Round to the nearest thousand as possible values (depending on
        # the database and geolib) include 5439084, 5439100, 5439101.
        rounded_value = z.area.sq_m
        rounded_value -= z.area.sq_m % 1000
        self.assertEqual(rounded_value, 5439000)

    @skipUnlessDBFeature("has_Area_function")
    @skipIfDBFeature("supports_area_geodetic")
    def test_geodetic_area_raises_if_not_supported(self):
        with self.assertRaisesMessage(NotImplementedError, 'Area on geodetic coordinate systems not supported.'):
            Zipcode.objects.annotate(area=Area('poly')).get(code='77002')