mutli-select没有值时，单击提交按钮时，Django表单未提交

如何解决mutli-select没有值时，单击提交按钮时，Django表单未提交

我正在使用django-taggit库来表示“问题”字段。在模型中将其设置为blank = True。当我尝试提交此表单时，如果在多选字段中选择了一个或多个问题，则效果很好，但如果该字段未选择任何内容，则不会提交。问题在于它甚至不会引发错误或未在视图代码中出现断点，因此我无法对其进行调试以找出问题所在。有什么想法吗？

Django Form类：

class CreateJob(ModelForm):
    def __init__(self,*args,**kwargs):
        selected_questions = kwargs.pop('selected_questions')
        super(CreateJob,self).__init__(*args,**kwargs)
        self.initial['questions'] = selected_questions

    questions = ModelMultipleChoiceField(queryset=Tag.objects.all())

    class Meta:
        model = Job
        fields = ('name','description','skills_required','submission_deadline','participation_ends','tagged_freelancers','assigned_freelancer','questions')
        widgets = {
            'submission_deadline': DateInput(attrs={'data-provide': 'datepicker'}),'participation_ends': DateInput(attrs={'data-provide': 'datepicker'})
        }

Django视图：

def job_edit(request,job_id,template_name='projects/job_create.html'):
    job = get_object_or_404(Job,pk=job_id)
    job_form = CreateJob(request.POST or None,instance=job,selected_questions=job.questions.all())
    if job_form.is_valid():
        job_form.save()
        return redirect('job_board')
    return render(request,template_name,{'job_form': job_form,'is_new': False})

HTML模板：

<div class="container">
    <div class="row justify-content-sm-center">
        <div class="col-sm-8">
            <div class="mb-3 text-left">
                {% if is_new %}
                <h1>New Job</h1>
                {% else %}
                <h1>Update Job</h1>
                {% endif %}
            </div>
            <form method="post" class="form">
                {% csrf_token %}
                {% bootstrap_field job_form.name %}
                {% bootstrap_field job_form.description %}
                {% bootstrap_field job_form.skills_required %}
                {% bootstrap_field job_form.submission_deadline %}
                {% bootstrap_field job_form.participation_ends %}
                {% bootstrap_field job_form.tagged_freelancers %}
                {% bootstrap_field job_form.assigned_freelancer %}
                {% bootstrap_field job_form.questions %}
                {% bootstrap_button "Submit" button_type="submit" button_class="btn-secondary" %}
            </form>
        </div>
    </div>
</div>