Django中的IntegrityError

我在一个表单中添加了一个Many2Many字段，现在当我提交时出现IntegrityError。精确的错误文本是

/add_person/ hireterm_person.mail_lists 的IntegrityError不允许为NULL

在添加新字段之前一切正常。当我查看调试更改时的POST数据时，我看到它正在传递，所以我不知道错误在哪里发生。

模型

from django.db import models
from django.forms import ModelForm
from django import forms
from django.contrib.auth.models import User
class Mailists(models.Model):
    name = models.CharField(blank=True, max_length=100)
    email = models.CharField(blank=True, max_length=100)
    def __unicode__(self):
        return u'%s' % (self.name)
class Person(models.Model):
    ROLE_CHOICES = (
        ('Mrkt', 'Marketing'),
        ('Fin/Off', 'Finance / Office'),
        ('Care', 'Care'),
        ('Sales', 'Sales'),
        )
    ROLE_TYPE = (
        ('Full', 'Full Time'),
        ('Part', 'Part Time'), 
        ('Intern', 'Intern'),
        )
    first_name = models.CharField(blank=True, max_length=100)
    last_name = models.CharField(blank=True, max_length=100)
    date_added = models.DateField(auto_now_add=True)
    date_start = models.DateField(auto_now=False)
    role = models.CharField(max_length=100, default = "", choices = ROLE_CHOICES)
    manager = models.ForeignKey('self', limit_choices_to = {'is_manager': True}, null=True, blank=True)
    title = models.CharField(blank=True, max_length=100)
    role_type = models.CharField(max_length=100, default = "", choices = ROLE_TYPE)
    laptop_needed = models.BooleanField(default=True)
    phone_needed = models.BooleanField(default=True)
    desk_loco = models.CharField(blank=True, max_length=100)
    mail_lists = models.ManyToManyField(Mailists, blank=True)
    notes = models.CharField(blank=True, max_length=500)
    is_manager = models.BooleanField(default=False)
    is_active = models.BooleanField(default=True)
    def __unicode__(self):
        return u'%s %s' % (self.first_name, self.last_name)
class PersonForm(ModelForm):
    mail_lists = forms.ModelMultipleChoiceField(queryset=Mailists.objects.all(), widget=forms.CheckboxSelectMultiple(), required=False)
    class Meta:
        model = Person

编辑

我添加了mail_lists = request.POST.getlist(\'mail_lists\')。当我在此添加打印时，返回的列表是所有复选框，但POST数据仍然是单个字符串，最后一个选中的框。

视图

from hireterm.models import Person, Mailists, PersonForm
from django.shortcuts import get_object_or_404, render
from django.template import Context, loader
from django.http import HttpResponseRedirect, HttpResponse
from django.contrib.auth.decorators import login_required
from django.contrib.auth import authenticate, login
from django.contrib.auth import logout
from django.core.mail import send_mail
@login_required
def home(request):
    return render(request, 'hireterm/home.html')
def add_person(request):
    if request.method == 'POST':
        mail_lists = request.POST.getlist('mail_lists') 
        person_form = PersonForm(request.POST)
        if person_form.is_valid(): 
            person_form.save()
            return HttpResponseRedirect('/new_hire') # Redirect after POST
    else:
        person_form = PersonForm() # An unbound form
    return render(request, 'hireterm/additem.html', {
        'form': person_form,
    })