Python django：使用models.ForeignKey下拉显示不出来模型已有的数据

from django.db import models

class Customer(models.Model):
    """
    客户表
    """

    name = models.CharField('姓名', max_length=32, blank=True, null=True, help_text='学员报名后，请改为真实姓名')
    phone = models.BigIntegerField('手机号', blank=True, null=True)
    qq = models.CharField('QQ', max_length=64, unique=True, help_text='QQ号必须唯一')
    qq_name = models.CharField('微信', max_length=64, blank=True, null=True)
    company= models.CharField('公司', max_length=64, blank=True, null=True)
    branch= models.CharField('部门', max_length=64, blank=True, null=True)
    position = models.CharField('职位', max_length=64, blank=True, null=True)
    urban = models.CharField('城市', max_length=64, blank=True, null=True)
    address = models.CharField('地址', max_length=64, blank=True, null=True)
    hometown= models.CharField('祖籍', max_length=64, blank=True, null=True)
    sex_type = (('male', '男'), ('female', '女'))
    sex = models.CharField("性别", choices=sex_type, max_length=16, default='male', blank=True, null=True)
    birthday = models.DateField('出生日期', default=None, help_text="格式yyyy-mm-dd", blank=True, null=True)

    source = models.CharField('客户来源', max_length=64, choices=source_type, default='qq')
    introduce_from = models.ForeignKey('Customer', verbose_name="介绍人", blank=True, null=True,
                                       on_delete=models.CASCADE)
    class_type = models.CharField("关系程度", max_length=64, choices=class_type_choices, default='fulltime')
    customer_note = models.TextField("客户备注", blank=True, null=True, )
    status = models.CharField("机构类型", choices=enroll_status_choices, max_length=64, default="unregistered",
                              help_text="选择客户此时的状态")

    date = models.DateTimeField("咨询日期", auto_now_add=True)
    last_consult_date = models.DateField("最后跟进日期", auto_now_add=True)

    deal_date = models.DateTimeField(auto_now_add=True,verbose_name="创建时间")
    #today = models.DateTimeField("今日日期",default=timezone.now,blank=True, null=True)

    consultant = models.ForeignKey('UserInfo', verbose_name="销售", related_name='customers', blank=True, null=True,
                                   on_delete=models.CASCADE, limit_choices_to={"depart_id": 1})
    class_list = models.CharField("业务类型", choices=range_choices, max_length=64, default="unregistered")


    def __str__(self):
        return str(self.name)

    def get_classlist(self):
        l = []
        for cls in self.class_list.all():
            l.append(str(cls))
        return mark_safe("<br>".join(l))

    def get_status(self):
        status_color = {
            "studying": "green",
            "signed": "#B03060",
            "unregistered": "red",
            "paid_in_full": "blue"
        }
        return mark_safe(
            "<span style='background-color:%s;color:white;padding:4px;display:inline-block;width:90px'>%s</span>" % (
            status_color[self.status], self.get_status_display()))


    class Meta:
        verbose_name = '客户列表'
        verbose_name_plural = '客户列表'

class ConsultRecord(models.Model):
    """
    跟进记录表
    """
    customer = models.ForeignKey(Customer, verbose_name="跟进的客户",blank=True, null=True,related_name='Customer.objects.all()',
                                on_delete=models.CASCADE)
    

    note = models.TextField(verbose_name="跟进内容...")
    status = models.CharField("跟进状态", max_length=8, choices=seek_status_choices, help_text="选择客户此时的状态")
    consultant = models.ForeignKey("UserInfo", verbose_name="跟进人", related_name='records', on_delete=models.CASCADE)
    date = models.DateTimeField("跟进日期", auto_now_add=True)
    delete_status = models.BooleanField(verbose_name='删除状态', default=False)

    def __str__(self):
        return str(self.customer) + str(self.consultant)

    class Meta:
        verbose_name = "跟进记录表"
        verbose_name_plural = "跟进记录表"

请问有form源码吗