你存了'b.py'吗? 你必须先保存'b.py'。

我通过引用一个以错误方式导入的enum得到了这个错误，例如:

from package import MyEnumClass
# ...
# in some method:
return MyEnumClass.Member

正确的导入:

from package.MyEnumClass import MyEnumClass

希望这能帮助到别人

以上所有的答案都很棒，但我想在这里插一句。如果你没有发现上面提到的任何问题，试着清理一下你的工作环境。这对我很管用。

我曾多次遇到这个问题，但我并没有试图深入挖掘。现在我明白主要问题了。

这一次，我的问题是从不同的模块导入Serializers (django和restframework)，如下所示:

from rest_framework import serializers

from common import serializers as srlz
from prices import models as mdlpri

# the line below was the problem 'srlzprod'
from products import serializers as srlzprod

我遇到了一个这样的问题:

from product import serializers as srlzprod
ModuleNotFoundError: No module named 'product'

我想要完成的是:

class CampaignsProductsSerializers(srlz.DynamicFieldsModelSerializer):
    bank_name = serializers.CharField(trim_whitespace=True,)
    coupon_type = serializers.SerializerMethodField()
    promotion_description = serializers.SerializerMethodField()

    # the nested relation of the line below
    product = srlzprod.ProductsSerializers(fields=['id','name',],read_only=True,)

因此，正如上面提到的如何解决它(顶级导入)，我继续做以下更改:

# change
product = srlzprod.ProductsSerializers(fields=['id','name',],read_only=True,)
# by 
product = serializers.SerializerMethodField()

# and create the following method and call from there the required serializer class
def get_product(self, obj):
        from products import serializers as srlzprod
        p_fields = ['id', 'name', ]
        return srlzprod.ProductsSerializers(
            obj.product, fields=p_fields, many=False,
        ).data

因此，django runserver的执行没有问题:

./project/settings/manage.py runserver 0:8002 --settings=settings_development_mlazo
Performing system checks...

System check identified no issues (0 silenced).
April 25, 2020 - 13:31:56
Django version 2.0.7, using settings 'settings_development_mlazo'
Starting development server at http://0:8002/
Quit the server with CONTROL-C.

代码行的最终状态如下:

from rest_framework import serializers

from common import serializers as srlz
from prices import models as mdlpri

class CampaignsProductsSerializers(srlz.DynamicFieldsModelSerializer):
    bank_name = serializers.CharField(trim_whitespace=True,)
    coupon_type = serializers.SerializerMethodField()
    promotion_description = serializers.SerializerMethodField()
    product = serializers.SerializerMethodField()

    class Meta:
        model = mdlpri.CampaignsProducts
        fields = '__all__'

    def get_product(self, obj):
        from products import serializers as srlzprod
        p_fields = ['id', 'name', ]
        return srlzprod.ProductsSerializers(
            obj.product, fields=p_fields, many=False,
        ).data

希望这能对其他人有所帮助。

问候,

在我使用python 2.7和numpy 1.15.0版本工作的情况下，它与

pip install statsmodels=="0.10.0"

导入的顺序是我遇到问题的原因:

a.py:

############
# this is a problem
# move this to below
#############
from b import NewThing

class ProblemThing(object):
    pass

class A(object):
   ###############
   # add it here
   # from b import NewThing
   ###############
   nt = NewThing()
   pass

b.py:

from a import ProblemThing

class NewThing(ProblemThing):
    pass

这只是另一个例子，类似于richieindie的答案，但是有类。