遵循凯文·迪亚斯 (Kevin Dias) 的指示本文，我尝试为两个相关模型生成一种表单。这似乎适用于一对多关系，但是我在使用多对多关系时遇到了问题。
以下是用户角色管理的一些示例代码：
#models.py
from django.db import models
class Role(models.Model): # for each role there can be multiple users
role_name=models.CharField(max_length=20)
class User(models.Model): # each user can have multiple roles
name=models.CharField(max_length=20)
role=models.ManyToManyField(Role, through='UserRole')
class UserRole(models.Model): # table to store which user has which roles
role=models.ForeignKey(Role)
user=models.ForeignKey(User)
# forms.py
from django.forms import ModelForm
from django.forms.models import inlineformset_factory
from rightmanagement.models import Role, User
class UserForm(ModelForm):
class Meta:
model = User
RoleFormSet = inlineformset_factory(User, Role) # this is probably the line that causes the problem
# views.py
from django.http import HttpResponseRedirect
from rightmanagement.models import User
from rightmanagement.forms import RoleFormSet, UserForm
# Create view
from django.views.generic import CreateView
class UserCreate(CreateView):
model = User
form_class = UserForm
def get(self, request, *args, **kwargs):
"""
Handles GET requests and instantiates blank versions of the form
and its inline formsets.
"""
self.object = None
form_class = self.get_form_class()
form = self.get_form(form_class)
role_form = RoleFormSet()
return self.render_to_response(
self.get_context_data(form=form,
role_form=role_form))
def post(self, request, *args, **kwargs):
"""
Handles POST requests, instantiating a form instance and its inline
formsets with the passed POST variables and then checking them for
validity.
"""
self.object = None
form_class = self.get_form_class()
form = self.get_form(form_class)
role_form = RoleFormSet(self.request.POST)
if (form.is_valid() and role_form.is_valid()):
return self.form_valid(form, role_form)
else:
return self.form_invalid(form, role_form)
def form_valid(self, form, role_form):
"""
Called if all forms are valid. Creates a Recipe instance along with
associated Ingredients and Instructions and then redirects to a
success page.
"""
self.object = form.save()
role_form.instance = self.object
role_form.save()
return HttpResponseRedirect(self.get_success_url())
def form_invalid(self, form, role_form):
"""
Called if a form is invalid. Re-renders the context data with the
data-filled forms and errors.
"""
return self.render_to_response(
self.get_context_data(form=form,
role_form=role_form))
这些设置会导致错误消息<class 'rightmanagement.models.Role'> has no ForeignKey to <class 'rightmanagement.models.User'>.
做了一些研究我发现了这一点：Django inlineformset_factory 和 ManyToMany 字段。内联表单集似乎仅适用于ForeignKey但不是为了ManyToManyField. Also the docs可以这样解释。
但是，我认为在这种特殊情况下，使用外键而不是多对多关系没有任何意义。对于多对多关系，Django 内置内联表单集的挂件是什么样子的？目的是构建一个表单，允许将用户分配给已经存在的角色，或者创建新角色并将其分配给用户（如果尚不存在）。
