Django M2M与管理员的关系问题，使用带有多选的中间表

from django.db import models

class Admin(models.Model):
    name = models.CharField(max_length=100)
    permissions = models.ManyToManyField('Permission', through='AdminPermission')

class Permission(models.Model):
    name = models.CharField(max_length=100)

class AdminPermission(models.Model):
    admin = models.ForeignKey(Admin, on_delete=models.CASCADE)
    permission = models.ForeignKey(Permission, on_delete=models.CASCADE)

from django import forms
from django.contrib import admin

class AdminForm(forms.ModelForm):
    permissions = forms.ModelMultipleChoiceField(
        queryset=Permission.objects.all(),
        widget=admin.widgets.FilteredSelectMultiple('Permissions', False),
        required=False
    )

    class Meta:
        model = Admin
        fields = '__all__'

class AdminAdmin(admin.ModelAdmin):
    form = AdminForm

admin.site.register(Admin, AdminAdmin)