python - 另一个无法在指定中间模型的 ManyToManyField 上设置值

Question

我收到错误:

无法在指定中间模型的 ManyToManyField 上设置值。请改用 ipaswdb.ProviderLocations 的管理器。

我被 ipaswdb.ProviderLocations 管理器部分绊倒了，我认为我在 views.py 中的代码中正确地处理了 form_valid 中模型的 M2M 关系。

我确实看到了这个 SO 答案: django Cannot set values on a ManyToManyField which specifies an intermediary model. Use Manager instead

这导致我添加了一个 self.object.save() 但这似乎没有做任何事情。在 UpdateView 中，代码似乎有效，但我去检查，即使我通过打印语句选择了两个位置，我可以看到从表单返回，但我只在数据库中看到一个...

我确实在 CreateView 上看到了这个错误，无论是否添加了 self.object.save() (我以为我得到它是因为 commit=False 并且对象尚未保存)。涉及到的模型我也会放在最下面，它们的关系比较复杂。

class ProviderCreateView(CreateView):
    model = Provider
    form_class = ProviderForm
    template_name = 'ipaswdb/provider/provider_form.html'
    success_url = 'ipaswdb/provider/'

    def form_valid(self, form):
        self.object = form.save(commit=True) #traceback shows this as offending line
        ProviderLocations.objects.filter(provider=self.object).delete()
        self.object.save()

        for group_location in form.cleaned_data['group_locations']:
            location = ProviderLocations()
            location.provider = self.object
            location.group_location = group_location
            location.save()

        return super(ModelFormMixin, self).form_valid(form)

class ProviderUpdateView(UpdateView):
    model = Provider
    form_class = ProviderForm
    template_name = 'ipaswdb/provider/provider_form.html'
    success_url = 'ipaswdb/provider/'


    def form_valid(self, form):
        self.object = form.save(commit=False)
        ProviderLocations.objects.filter(provider=self.object).delete()
        self.object.save()
        for group_location in form.cleaned_data['group_locations']:
            print("here!" + self.object.first_name)
            location = ProviderLocations()
            location.provider = self.object
            location.group_location = group_location
            location.save()

            return super(ModelFormMixin, self).form_valid(form)

然后是我的模型:

class Provider(models.Model):
    first_name = models.CharField(max_length = 50)
    last_name = models.CharField(max_length = 50)
    date_of_birth = models.DateField(auto_now_add=False) 
    group_locations = models.ManyToManyField('GroupLocations', through='ProviderLocations', blank=True, null=True)
    etc...

class ProviderLocations(models.Model):
        #group_location = models.ForeignKey('GroupLocations', on_delete=models.CASCADE)
    provider = models.ForeignKey('Provider', on_delete=models.CASCADE)
    group_location = models.ForeignKey('GroupLocations', on_delete=models.CASCADE)
    created_at=models.DateField(auto_now_add=True)
    updated_at=models.DateField(auto_now=True)
    def __str__(self):
        return self.provider.first_name

class GroupLocations(models.Model):
    address = models.ForeignKey('Address', on_delete= models.SET_NULL, null=True)
    group = models.ForeignKey('Group', on_delete=models.CASCADE)
    doing_business_as = models.CharField(max_length = 255)
    created_at=models.DateField(auto_now_add=True)
    updated_at=models.DateField(auto_now=True)
    def __str__(self):
        return self.doing_business_as


class Group(models.Model):
    group_name = models.CharField(max_length=50) 
    etc...

好的，当打印语句显示它试图添加的多个位置时，调试记录器一直向上显示此 sql 只执行一个 INSERT:

0.001) SELECT "ipaswdb_grouplocations"."id", "ipaswdb_grouplocations"."address_id", "ipaswdb_grouplocations"."group_id", "ipaswdb_grouplocations"."doing_business_as", "ipaswdb_grouplocations"."created_at", "ipaswdb_grouplocations"."updated_at" FROM "ipaswdb_grouplocations" WHERE "ipaswdb_grouplocations"."id" IN (3, 2, 5, 4); args=(3, 2, 5, 4)
(0.000) BEGIN; args=None
(0.000) DELETE FROM "ipaswdb_providerlocations" WHERE "ipaswdb_providerlocations"."provider_id" = NULL; args=(None,)
(0.000) BEGIN; args=None
(0.001) INSERT INTO "ipaswdb_provider" ("first_name", "last_name", "date_of_birth", "license_number", "license_experation", "dea_number", "dea_experation", "phone", "fax", "ptan", "caqh_number", "effective_date", "provider_npi", "provisional_effective_date", "date_joined", "provider_contact", "credentialing_contact", "notes", "hospital_affiliation", "designation_id", "specialty_id", "created_at", "updated_at") VALUES ('Onemore', 'Test', '2016-08-12', 'kljlk', '2016-08-12', 'kljjkl', '2016-08-12', '', '', '', 'lk;fsd', '2016-08-12', 'jksalfas', '2016-08-12', '2016-08-12', 'kj;jasdf', ';kjsfas', '', '', NULL, NULL, '2016-08-12', '2016-08-12'); args=[u'Onemore', u'Test', u'2016-08-12', u'kljlk', u'2016-08-12', u'kljjkl', u'2016-08-12', u'', u'', u'', u'lk;fsd', u'2016-08-12', u'jksalfas', u'2016-08-12', u'2016-08-12', u'kj;jasdf', u';kjsfas', u'', u'', None, None, u'2016-08-12', u'2016-08-12']
here!IPAABQ     <-- all the locations to add is with the here!
here!ststs
here!2312
here!fsfd315
(0.000) BEGIN; args=None

看一个插页

(0.000) INSERT INTO "ipaswdb_providerlocations" ("provider_id", "group_location_id", "created_at", "updated_at") VALUES (22, 5, '2016-08-12', '2016-08-12'); args=[22, 5, u'2016-08-12', u'2016-08-12']
[12/Aug/2016 19:46:26] "POST /ipaswdb/provider/add/ HTTP/1.1" 302 0
(0.001) SELECT COUNT(*) AS "__count" FROM "ipaswdb_provider"; args=()
(0.000) SELECT "ipaswdb_provider"."id", "ipaswdb_provider"."first_name", "ipaswdb_provider"."last_name", "ipaswdb_provider"."date_of_birth", "ipaswdb_provider"."license_number", "ipaswdb_provider"."license_experation", "ipaswdb_provider"."dea_number", "ipaswdb_provider"."dea_experation", "ipaswdb_provider"."phone", "ipaswdb_provider"."fax", "ipaswdb_provider"."ptan", "ipaswdb_provider"."caqh_number", "ipaswdb_provider"."effective_date", "ipaswdb_provider"."provider_npi", "ipaswdb_provider"."provisional_effective_date", "ipaswdb_provider"."date_joined", "ipaswdb_provider"."provider_contact", "ipaswdb_provider"."credentialing_contact", "ipaswdb_provider"."notes", "ipaswdb_provider"."hospital_affiliation", "ipaswdb_provider"."designation_id", "ipaswdb_provider"."specialty_id", "ipaswdb_provider"."created_at", "ipaswdb_provider"."updated_at" FROM "ipaswdb_provider" LIMIT 3; args=()
[12/Aug/2016 19:46:26] "GET /ipaswdb/provider/add/ipaswdb/provider/ HTTP/1.1" 200 4835

看起来有点像回溯:

Environment:


Request Method: POST
Request URL: http://localhost:8001/ipaswdb/provider/add/

Django Version: 1.9.5
Python Version: 2.7.11
Installed Applications:
['ipaswdb.apps.IpaswdbConfig',
 'django.contrib.admin',
 'django.contrib.auth',
 'django.contrib.contenttypes',
 'django.contrib.sessions',
 'django.contrib.messages',
 'django.contrib.staticfiles']
Installed Middleware:
['django.middleware.security.SecurityMiddleware',
 'django.contrib.sessions.middleware.SessionMiddleware',
 'django.middleware.common.CommonMiddleware',
 'django.middleware.csrf.CsrfViewMiddleware',
 'django.contrib.auth.middleware.AuthenticationMiddleware',
 'django.contrib.auth.middleware.SessionAuthenticationMiddleware',
 'django.contrib.messages.middleware.MessageMiddleware',
 'django.middleware.clickjacking.XFrameOptionsMiddleware']



Traceback:

File "/usr/local/lib/python2.7/site-packages/django/core/handlers/base.py" in get_response
  149.                     response = self.process_exception_by_middleware(e, request)

File "/usr/local/lib/python2.7/site-packages/django/core/handlers/base.py" in get_response
  147.                     response = wrapped_callback(request, *callback_args, **callback_kwargs)

File "/usr/local/lib/python2.7/site-packages/django/views/generic/base.py" in view
  68.             return self.dispatch(request, *args, **kwargs)

File "/usr/local/lib/python2.7/site-packages/django/views/generic/base.py" in dispatch
  88.         return handler(request, *args, **kwargs)

File "/usr/local/lib/python2.7/site-packages/django/views/generic/edit.py" in post
  256.         return super(BaseCreateView, self).post(request, *args, **kwargs)

File "/usr/local/lib/python2.7/site-packages/django/views/generic/edit.py" in post
  222.             return self.form_valid(form)

File "/Users/shane.thomas/programming/py3env/ipa_django/mysite/ipaswdb/views.py" in form_valid
  38.       self.object = form.save(commit=True)

File "/usr/local/lib/python2.7/site-packages/django/forms/models.py" in save
  452.             self._save_m2m()

File "/usr/local/lib/python2.7/site-packages/django/forms/models.py" in _save_m2m
  434.                 f.save_form_data(self.instance, cleaned_data[f.name])

File "/usr/local/lib/python2.7/site-packages/django/db/models/fields/related.py" in save_form_data
  1618.         setattr(instance, self.attname, data)

File "/usr/local/lib/python2.7/site-packages/django/db/models/fields/related_descriptors.py" in __set__
  481.         manager.set(value)

File "/usr/local/lib/python2.7/site-packages/django/db/models/fields/related_descriptors.py" in set
  882.                     (opts.app_label, opts.object_name)

Exception Type: AttributeError at /ipaswdb/provider/add/
Exception Value: Cannot set values on a ManyToManyField which specifies an intermediary model. Use ipaswdb.ProviderLocations's Manager instead.

Answer 1

保存时不要提交。如记录here如果您指定 commit=True，它将尝试同时写入 M2M 映射。你不希望这种情况发生。

通过指定 False 值，您可以稍后调用 save_m2m 来保存映射，或者创建您自己的映射。您需要执行后者，而您的其余代码已经为此做了正确的事情。