Django：在 ModelField 中显示实例字符串值

如何解决Django：在 ModelField 中显示实例字符串值

我在将它发送到前端之前初始化了一个 ModelForm。一切正常，但生成的表单显示“associative_subscription”和“course” ID，但我想显示转换后的字符串值（对用户更易读）。

这是我的代码：

models.py

class CourseSubscription(models.Model):
    start_date = models.DateField(default=datetime.date.today,null=False,blank=False,verbose_name="Data di inizio")
    associative_subscription = models.ForeignKey(AssociativeSubscription,on_delete= models.CASCADE,verbose_name="Iscrizione Associativa")
    course = models.ForeignKey(Course,verbose_name="Corso")
    fee_paid = models.DecimalField(max_digits=7,decimal_places=2,verbose_name="Quota versata")
    payment_completed = models.BooleanField(default=False,verbose_name="Pagamento Completo")
    expiration_date = models.DateField(editable=False,verbose_name="Scadenza")
    payment_method = models.CharField(
        max_length = 4,verbose_name="Modalità di pagamento",choices=PAYMENTS
    )
    class Meta:
       unique_together = ("associative_subscription","course")
    def __str__(self):
        return  u'%s  / Iscrizione corso %s dal %s al %s' % (self.associative_subscription.member,self.course,self.start_date.strftime('%d/%m/%Y'),self.expiration_date.strftime('%d/%m/%Y'))

forms.py

class CourseSubscriptionForm(ModelForm):
    def __init__(self,max_value,*args,**kwargs):
        super(CourseSubscriptionForm,self).__init__(*args,**kwargs)
        self.fields['fee_paid'] = forms.DecimalField(  
            max_digits=7,required=True,label="Quota Versata",min_value=0.01,max_value=max_value,help_text= f"Valore Massimo: {max_value}",widget = forms.Numberinput()
        )
    class Meta:
        model = CourseSubscription
        exclude = ('expiration_date','payment_completed')
        widgets = {
            'associative_subscription': forms.TextInput(attrs={'readonly':'readonly'}),'course' : forms.TextInput(attrs={'readonly':'readonly'})
        }

views.py

def add_course_subscription(request,associative_subscription_id,course_id):
    if request.method == 'POST':
        ...
        return JsonResponse(context)
    
    associative_subscription = AssociativeSubscription.objects.get(id= associative_subscription_id)
    course = Course.objects.get(id = course_id)
    remaining_fee = course.inscription_price
    form = CourseSubscriptionForm(
        initial={
            'associative_subscription': associative_subscription,'course':course,'fee_paid': 1.00,},max_value = remaining_fee
    )
    return render(request,'form.html',{'form': form})

That's what I obtain,but I want the __str__ result of the instance