Django Createview外键字段的默认值

Question

我有两个 classes(tables) 学校和学生有关联（外键）当我创建一个新学生时，我希望它自动填充学校字段（这是学校 class(table) 中名称字段的外键，因为它已经链接到学校。我试过 def get_initial(self): 没有运气（它给我错误）。如果有人能指出我做错了什么……谢谢 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

由于您将学校的 slug 存储在 URL 中，最好将学校字段保留在表格之外。然后就可以在form_valid方法中设置学校了：

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

如果您想为 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)

你是一个压倒一切的 get_initial 方法，它用于 Returns 用于此视图上表单的初始数据，实际上并未向你的字段添加默认值

Django Createview外键字段的默认值

Django Createview default value for a foreign key field

python

django

django-class-based-views