我有这个模型:
class Marker(models.Model):
location = models.PointField(geography=True, unique=True)
当我尝试通过管理界面添加 Marker 实例时,它会引发ValueError
:
File "django/core/handlers/base.py" in get_response
111. response = callback(request, *callback_args, **callback_kwargs)
File "django/contrib/admin/options.py" in wrapper
366. return self.admin_site.admin_view(view)(*args, **kwargs)
File "django/utils/decorators.py" in _wrapped_view
91. response = view_func(request, *args, **kwargs)
File "django/views/decorators/cache.py" in _wrapped_view_func
89. response = view_func(request, *args, **kwargs)
File "django/contrib/admin/sites.py" in inner
196. return view(request, *args, **kwargs)
File "django/utils/decorators.py" in _wrapper
25. return bound_func(*args, **kwargs)
File "django/utils/decorators.py" in _wrapped_view
91. response = view_func(request, *args, **kwargs)
File "django/utils/decorators.py" in bound_func
21. return func(self, *args2, **kwargs2)
File "django/db/transaction.py" in inner
209. return func(*args, **kwargs)
File "django/contrib/admin/options.py" in add_view
937. if form.is_valid():
File "django/forms/forms.py" in is_valid
124. return self.is_bound and not bool(self.errors)
File "django/forms/forms.py" in _get_errors
115. self.full_clean()
File "django/forms/forms.py" in full_clean
272. self._post_clean()
File "django/forms/models.py" in _post_clean
338. self.validate_unique()
File "django/forms/models.py" in validate_unique
347. self.instance.validate_unique(exclude=exclude)
File "django/db/models/base.py" in validate_unique
633. errors = self._perform_unique_checks(unique_checks)
File "django/db/models/base.py" in _perform_unique_checks
724. if qs.exists():
File "django/db/models/query.py" in exists
565. return self.query.has_results(using=self.db)
File "django/db/models/sql/query.py" in has_results
441. return bool(compiler.execute_sql(SINGLE))
File "django/db/models/sql/compiler.py" in execute_sql
808. sql, params = self.as_sql()
File "django/db/models/sql/compiler.py" in as_sql
82. where, w_params = self.query.where.as_sql(qn=qn, connection=self.connection)
File "django/db/models/sql/where.py" in as_sql
91. sql, params = child.as_sql(qn=qn, connection=connection)
File "django/db/models/sql/where.py" in as_sql
94. sql, params = self.make_atom(child, qn, connection)
File "django/contrib/gis/db/models/sql/where.py" in make_atom
47. spatial_sql = connection.ops.spatial_lookup_sql(data, lookup_type, params_or_value, lvalue.field, qn)
File "django/contrib/gis/db/backends/postgis/operations.py" in spatial_lookup_sql
497. '"%s" lookup.' % lookup_type)
Exception Type: ValueError at /admin/coremap/marker/add/
Exception Value: PostGIS geography does not support the "exact" lookup.
据此,geography
类型确实没有字段exact
查找。有什么方法可以在unique
不使用的情况下完成约束exact
?
我在用着:
- PostgreSQL 9.1
- 地理信息系统 1.5
- Django 1.4.3