我是工具工作的新手。目前我在Django中最喜欢的软件包已经过时了，现在似乎无人问津。因此我想研究它。
问题：
https://github.com/philippbosch/django-geoposition/issues/100
Traceback (most recent call last):
File "/Users/sarit/.pyenv/versions/3.6.4/envs/poink/lib/python3.6/site-packages/django/core/handlers/exception.py", line 35, in inner
response = get_response(request)
File "/Users/sarit/.pyenv/versions/3.6.4/envs/poink/lib/python3.6/site-packages/django/core/handlers/base.py", line 128, in _get_response
response = self.process_exception_by_middleware(e, request)
File "/Users/sarit/.pyenv/versions/3.6.4/envs/poink/lib/python3.6/site-packages/django/core/handlers/base.py", line 126, in _get_response
response = wrapped_callback(request, *callback_args, **callback_kwargs)
File "/Users/sarit/.pyenv/versions/3.6.4/lib/python3.6/contextlib.py", line 52, in inner
return func(*args, **kwds)
File "/Users/sarit/.pyenv/versions/3.6.4/envs/poink/lib/python3.6/site-packages/django/views/decorators/csrf.py", line 54, in wrapped_view
return view_func(*args, **kwargs)
File "/Users/sarit/.pyenv/versions/3.6.4/envs/poink/lib/python3.6/site-packages/rest_framework/viewsets.py", line 95, in view
return self.dispatch(request, *args, **kwargs)
File "/Users/sarit/.pyenv/versions/3.6.4/envs/poink/lib/python3.6/site-packages/rest_framework/views.py", line 494, in dispatch
response = self.handle_exception(exc)
File "/Users/sarit/.pyenv/versions/3.6.4/envs/poink/lib/python3.6/site-packages/rest_framework/views.py", line 454, in handle_exception
self.raise_uncaught_exception(exc)
File "/Users/sarit/.pyenv/versions/3.6.4/envs/poink/lib/python3.6/site-packages/rest_framework/views.py", line 491, in dispatch
response = handler(request, *args, **kwargs)
File "/Users/sarit/.pyenv/versions/3.6.4/envs/poink/lib/python3.6/site-packages/rest_framework/mixins.py", line 22, in create
headers = self.get_success_headers(serializer.data)
File "/Users/sarit/.pyenv/versions/3.6.4/envs/poink/lib/python3.6/site-packages/rest_framework/serializers.py", line 537, in data
ret = super(Serializer, self).data
File "/Users/sarit/.pyenv/versions/3.6.4/envs/poink/lib/python3.6/site-packages/rest_framework/serializers.py", line 262, in data
self._data = self.to_representation(self.instance)
File "/Users/sarit/.pyenv/versions/3.6.4/envs/poink/lib/python3.6/site-packages/rest_framework/serializers.py", line 504, in to_representation
ret[field.field_name] = field.to_representation(attribute)
File "/Users/sarit/.pyenv/versions/3.6.4/envs/poink/lib/python3.6/site-packages/rest_framework/fields.py", line 1858, in to_representation
return self.model_field.value_to_string(obj)
File "/Users/sarit/.pyenv/versions/3.6.4/envs/poink/src/django-geoposition/geoposition/fields.py", line 50, in value_to_string
value = self._get_val_from_obj(obj)
AttributeError: 'GeopositionField' object has no attribute '_get_val_from_obj'
官方文档：
https://docs.djangoproject.com/en/2.0/releases/2.0/
删除了Field._get_val_from_obj（）。
问题：
如何解决这个错误？
def value_to_string(self, obj):
value = self._get_val_from_obj(obj)
return smart_text(value)
更新
https://github.com/pennersr/django-allauth/issues/1865
@linaskilius说
Django建议改为使用Field.value_from_object（）。