Question

我的两个模型：

class BusinessType(models.Model):
    def __str__(self):
        return self.name

    name = models.CharField(max_length=200)
    description = models.CharField(max_length=200)

class Business(models.Model):
    def __str__(self):
        return self.name

    name = models.CharField(max_length=200)
    description = models.CharField(max_length=200)
    bus_type = models.ForeignKey(BusinessType, on_delete=models.CASCADE, name="type")

class Appointment(models.Model):
    from datetime import datetime

    business = models.ForeignKey(Business, on_delete=models.CASCADE, name="appointments")
    done = False

    created_at = models.DateTimeField(auto_now_add=True)
    updated_at = models.DateTimeField(auto_now=True)

现在，我将此上下文添加到我的视图中：

'business':Business.objects.order_by('name'),

我的模板：

{{business|length}}<hr />
    {%for business_entry in business%}
        {{business_entry.appointments.all|length}}
    {%endfor%}

现在业务长度输出为“ 2”，是的，我有两个业务对象。

但是对于约会，我得到的值为“ 0”，这是不正确的。

我在做什么错了？

Answer 1

应为related_name="appointments"，而不是name="appointments"。

因此，更改：

business = models.ForeignKey(Business, on_delete=models.CASCADE, name="appointments")

收件人：

business = models.ForeignKey(Business, on_delete=models.CASCADE, related_name="appointments")

您可能需要阅读：ForeignKey.related_name

Django在视图中获取子对象

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