问使用django引导模式窗体时如何在窗体中预填充字段

EN

class userSchoolYear(models.Model):
    user_in_school = models.ForeignKey(get_user_model(), null=True, on_delete=models.CASCADE)
    school = models.ForeignKey(sifMusicSchool, on_delete=models.CASCADE)
    school_year = models.ForeignKey(sifSchoolYear, on_delete=models.CASCADE)
    school_year_grade = models.CharField(max_length=4, choices=IZBOR_RAZREDA, default=None, null=True)
    user_instrument = models.ForeignKey(instType, on_delete=models.CASCADE, default=None, null=True)
    user_profesor = models.ForeignKey(profSchool, on_delete=models.CASCADE, default=None, null=True)

class SchoolYearCreateView(BSModalCreateView):
    template_name = 'school_year.html'
    form_class = SchoolYearForm
    success_message = 'Success!'
    success_url = reverse_lazy('school')

    def __init__(self, *args, **kwargs):
        self.form_class.user_in_school = 'johnny'  ### HERE
        print(user.username)
        super().__init__(*args, **kwargs)

class SchoolYearForm(BSModalForm):

    class Meta:
            model = userSchoolYear
            fields = '__all__'