一对多选项不会出现在Django模型中

我对Django还很陌生,我很难搞错Django模型形式中遗漏了什么。我想在表单中显示一个带有预定义值的下拉列表,但由于某些原因,选项从未出现。以下是来自模型.py

LOAN_STATUS = (
    ('m', 'Maintenance'),
    ('o', 'On loan'),
    ('a', 'Available'),
    ('r', 'Reserved'),
)

class Status (models.Model):
    status = models.CharField(
            max_length=50,
            choices=LOAN_STATUS,
            blank=True,
            default='m',
        )
    class Meta:
        db_table = 'Status'

class Property(models.Model):
   propertyID = models.AutoField(primary_key=True)
   status = models.ForeignKey(Status, on_delete=models.SET_NULL, null=True)

   def __str__(self):
      return self.propertyTitle

下面是ModelForm中的代码

class CreateAdvertisementForm(ModelForm):
    class Meta:
        model = Property
        exclude = ['propertyID']
        fields = ('status',)

下面是我模板中的代码

{% block body %}
<form method="POST" class="post-form">
    {% csrf_token %}
    {{ form.as_p }}

    <button type="submit" class="save btn btn-default">Save</button>
</form>{% endblock %}

请帮我弄清楚出了什么问题。