Django Createview外键字段的默认值

Question

我有两个班级（表），学校和学生在一起（外键），当我创建一个新学生时，我希望它自动填写学校字段（这是在学校班级（表）中命名字段的外键）我曾经尝试过def get_initial（self）：运气不好（它给我带来错误）。如果有人可以指出我在做什么错……感谢Models.py：

class School(models.Model):
    school_pk = models.AutoField(primary_key=True)
    name = models.CharField(max_length=256)
    principal = models.CharField(max_length=256)
    location = models.CharField(max_length=256)
    def __str__(self):
        return str(self.name)
    def get_absolute_url(self):
        return reverse("basic_app:school_detail",kwargs={'school_pk':self.school_pk})
class Student(models.Model):
    student_pk = models.AutoField(primary_key=True)
    name = models.CharField(max_length=256)
    age = models.PositiveIntegerField()
    school = models.ForeignKey(School,related_name='students',on_delete=models.CASCADE,default=None)

    def __str__(self):
        return self.name
    def get_absolute_url(self):
        return reverse("basic_app:student_detail",kwargs={'student_pk':self.student_pk,'school':self.school})

views.py：

class StudentCreateView(CreateView):
    fields = ("name","age","school")
    model = models.Student
    template_name = 'basic_app/student_form.html'

    pk_url_kwarg = 'student_pk'
    slug_url_kwarg='school'
    def get_initial(self):
        school = get_object_or_404(models.School, school_pk=self.kwargs.get('school_pk'))
        return {
        'school':school,
    }

Answer 1

由于您是在URL中存储学校的子弹，因此最好不要在表格中添加“学校”字段。 然后，您可以使用form_valid方法设置学校：

from django.shortcuts import get_object_or_404

class StudentCreateView(CreateView):
    fields = ("name","age",)  # don't include 'school' here
    ...

    def form_valid(self, form):
        school = get_object_or_404(School, slug=self.kwargs['school'])
        form.instance.school = school
        return super(StudentCreateView, self).form_valid(form)

Answer 2

如果要为FK字段提供默认值，请使用default属性。 Django已经提供了向您的字段添加默认值的选项。

DEFAULT_SCHOOL_ID = 1
class Student(models.Model):
   ...
   school=models.ForeignKey(School, default=DEFAULT_SCHOOL_ID)

您是覆盖其中的get_initial方法，该方法用于返回此视图上用于表单的初始数据，而实际上未向您的字段添加默认值