python - 如何通过用户在 django 模板中显示与反向引用的关系？

Question

我有这样的模型

class Employee(models.Model):
    """Employee information."""
    user = models.ForeignKey(settings.AUTH_USER_MODEL, on_delete=models.CASCADE, related_name='employee', unique=True)
    position = models.CharField("current position in a company", max_length=64, blank=True)
    birth_date = models.DateField("date of birth", null=True)
    skills = models.ManyToManyField(
        Technology, through="Skill", verbose_name="skills", blank=True)


class Technology(models.Model):
    """Technologies."""
    name = models.CharField('technology name', max_length=32, unique=True)

class Skill(models.Model):
    """Information about an employee's skills."""
    LEVELS = (
        ('basic', 'Basic'),
        ('intermediate', 'Intermediate'),
        ('advanced', 'Advanced'),
        ('expert', 'Expert'),
    )
    employee = models.ForeignKey(
        Employee, on_delete=models.CASCADE, related_name="employee_skills")
    technology = models.ForeignKey(Technology, on_delete=models.CASCADE)
    start_date = models.DateField(
        verbose_name='Works with since:')
    level = models.CharField("level", max_length=64, choices=LEVELS)

我不明白为什么我的模板代码不起作用

template.html

{{ user.employee.position }}
{{ user.employee.birth_date }}
{{ user.employee.summary }}

{% for i in  user.employee.skills.all %}
{{ i.technology.name }}
{{ i.level }}
{% endfor %}

我什么都看不到。所有模型都可以在管理面板上看到。然后我使用 TemplateView，例如

class AccountView(TemplateView):

    template_name = "profile.html"

    def get_context_data(self, **kwargs):
        context = super(AccountView, self).get_context_data(**kwargs)      
        context['skills'] = 
        Skill.objects.filter(employee__user=self.request.user)

        return context

然后一切正常。

Answer 1

建模有问题。你应该使用 OneToOneField在 Employee 之间和 User .本质上是一个 OneToOneField是独一无二的 ForeignKey .然而，它会改变一些逻辑，例如 user.employee将访问相关的Employee对象，不是 QuerySet的 Employee小号:

class Employee(models.Model):
    # ...
    user = models.<b>OneToOneField</b>(
        settings.AUTH_USER_MODEL,
        on_delete=models.CASCADE,
        related_name='employee'
    )
    # ...

在你的AccountView ，你统一'skills'凭借该员工的技能，确实:

class AccountView(TemplateView):

    template_name = "profile.html"

    def get_context_data(self, **kwargs):
        context = super(AccountView, self).get_context_data(**kwargs)      
        context.update(
            skills=Skill.objects.filter(employee__user=self.request.user)<b>.select_related('technology')</b>
        )
        return context

您可能想使用 .select_related(..)这里是为了防止所谓的“N+1 问题”，其中对于每个技能，您将进行额外的查询。

因此您可以通过以下方式呈现技能:

{% for skill in <b>skills</b> %}
    {{ skill.technology.name }}
    {{ skill.level }}
{% endfor %}

或者您可以通过以下方式访问:

{% for skill in <b>request.user.employee.employee_skills.all</b> %}
    {{ skill.technology.name }}
    {{ skill.level }}
{% endfor %}

虽然上面的方法不太安全，因为有可能 User没有相关Employee对象。