如何比较django 2.1中的两个字段?

模特儿 这是我的模型类,其中有两个表。在每个表上都有一个名为label的字段。我的问题是如何比较这两个标签并将值返回到一个新字段(returnlabel)

 class Server(models.Model):
     label = models.TextField(max_length=200,null=True)  #compare this
     upload1 = models.FileField(null=True, blank=True)
     Image1 = models.TextField(upload1, null=True)

class Android(models.Model):
     label=models.TextField(max_length=200,null=True) #with this
     imagestring=models.TextField(null=True,blank=True)
     returnlabel=models.TextField(null=True,blank=True) #return to this

序列化程序类

   class FoodSerializers(serializers.HyperlinkedModelSerializer):
       class Meta:
       model=Server
       fields=('url','label','Image1','upload1')

   class AndroidSerializers(serializers.ModelSerializer):

    class Meta:
    model = Android
    fields = ('label', 'imagestring', 'returnlabel')

意见

 class FoodViewSet(viewsets.ModelViewSet):
    queryset = Server.objects.all()
    serializer_class =FoodSerializers

class Androids(viewsets.ModelViewSet):
   queryset =Android.objects.all()
   serializer_class = AndroidSerializers