Fixed #17687 -- Made LayerMapping router-aware

from django.contrib.gis.tests.utils import mysql

from django.contrib.gis.utils.layermapping import (LayerMapping, LayerMapError,

    InvalidDecimal, MissingForeignKey)

from django.db import router

from django.test import TestCase

from .models import (

NUMS   = [1, 2, 1, 19, 1] # Number of polygons for each.

STATES = ['Texas', 'Texas', 'Texas', 'Hawaii', 'Colorado']

class LayerMapTest(TestCase):

    def test_init(self):

        lm.save(silent=True, strict=True)

        self.assertEqual(City.objects.count(), 3)

        self.assertEqual(City.objects.all().order_by('name_txt')[0].name_txt, "Houston")

class OtherRouter(object):

    def db_for_read(self, model, **hints):

        return 'other'

    def db_for_write(self, model, **hints):

        return self.db_for_read(model, **hints)

    def allow_relation(self, obj1, obj2, **hints):

        return None

    def allow_syncdb(self, db, model):

        return True

class LayerMapRouterTest(TestCase):

    def setUp(self):

        self.old_routers = router.routers

        router.routers = [OtherRouter()]

    def tearDown(self):

        router.routers = self.old_routers

    def test_layermapping_default_db(self):

        lm = LayerMapping(City, city_shp, city_mapping)

        self.assertEqual(lm.using, 'other')

import sys

from decimal import Decimal

from django.core.exceptions import ObjectDoesNotExist

from django.db import connections, DEFAULT_DB_ALIAS

from django.db import connections, router

from django.contrib.gis.db.models import GeometryField

from django.contrib.gis.gdal import (CoordTransform, DataSource,

    OGRException, OGRGeometry, OGRGeomType, SpatialReference)

    def __init__(self, model, data, mapping, layer=0,

                 source_srs=None, encoding=None,

                 transaction_mode='commit_on_success',

                 transform=True, unique=None, using=DEFAULT_DB_ALIAS):

                 transform=True, unique=None, using=None):

        """

        A LayerMapping object is initialized using the given Model (not an instance),

        a DataSource (or string path to an OGR-supported data file), and a mapping

            self.ds = data

        self.layer = self.ds[layer]

        self.using = using

        self.spatial_backend = connections[using].ops

        self.using = using if using is not None else router.db_for_write(model)

        self.spatial_backend = connections[self.using].ops

        # Setting the mapping & model attributes.

        self.mapping = mapping