Django Createview default value for a foreign key field

问题

I have two classes(tables) schools and students that are related together(foreignkey) When I create a new student I want it to autofill the school field (which is a foreignkey to name field in School class(table) because it is already linked to a school. I have tried def get_initial(self): with no luck (it give me error). If anyone can point out what I am doing wrong…thanks 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,
    }

回答1:

Since you are storing the school's slug in the URL, it would be better to leave the school field out of the form. Then you can set the school in the form_valid method:

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)

回答2:

If you want to give a default value for your FK field go with default attribute. Django already gives the option to add a default value to your field.

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

You are an overriding get_initial method its used for Returns the initial data to use for forms on this view not actually adding a default value to your field

来源：https://stackoverflow.com/questions/49857585/django-createview-default-value-for-a-foreign-key-field

标签

python

django

django-class-based-views