Django：“国家”对象没有“全部”属性

每当我尝试从 django admin 访问我的模型“Youtube”时，它都会向我显示此错误。我感觉我在YoutubeAdmin,getCountry方法中搞砸了。我该如何解决这个问题？找不到办法。它model Youtube doesn't have a filed getCountry在错误中说。

我的模型：

class Youtube(models.Model):
    link = models.CharField(max_length=2000)
    scrap_interval_hour = models.IntegerField(default=8)
    last_scrapped_datetime = models.DateTimeField(blank=True, null=True)
    is_feed = models.BooleanField(default=False)
    created_date = models.DateField(
        auto_now_add=True)
    # Foriegn Key
    country = models.ForeignKey(Country, on_delete=models.CASCADE)

    class Meta:
        ordering = ('created_date', )

行政

from django.contrib import admin
from fpn.models import Youtube
from datetime import timedelta

class YoutubeAdmin(admin.ModelAdmin):
    def get_fields(self, request, youtube=None):
        fields = super(YoutubeAdmin, self).get_fields(request, youtube)
        fields.remove('last_scrapped_datetime')

        if youtube:
            fields.remove('country')
        return fields

    model = Youtube
    list_per_page = 10
    list_display = ('link', 'is_feed',
                    'getCountry', 'last_scrapped_datetime')
    list_filter = ('country', 'is_feed', )

    def getCountry(self, obj):
        return "\n".join([coun.name for coun in obj.country.all()])