相关疑难解决方法(0)

看起来这应该是"容易"或至少在某处记录,我只是无法找到它.

让我们说我有一个模型:

class A(models.Model):
    users = models.ManyToMany('auth.User', blank=True)

现在我想迁移到一个through表来向ManyToMany关系添加字段...

class AUsers(models.Model):
    user = models.ForeignKey('auth.User')
    a = models.ForeignKey('A')
    new_field = models.BooleanField()

class A(models.Model):
    users = models.ManyToMany('auth.User', blank=True, through='AUsers')

然后我做:

% ./manage.py schemamigration app --auto

并不奇怪,它告诉我它将通过表删除原始的自动创建并为其创建一个新的AUsers.目前最好的做法是什么？是否有适当的方式迁移到新through表？我db_table在Meta 使用吗？我是不是through=...马上使用...然后做一个schemamigration --auto,然后a datamigration复制当前表(不知何故,不确定...)然后添加through关系,让它杀死表？

这里的诀窍是什么？这真的很难吗？

我正在尝试向我之前创建的ManyToMany字段添加订单.我基本上想订购图片集中的图片.我在Django 1.7上运行,所以没有更多的南迁移(我试图遵循这个教程:http://mounirmesselmeni.github.io/2013/07/28/migrate-django-manytomany-field-to-manytomany-through -with -南/)

这是我的"通过"关系:

class CollectionPictures(models.Model):
    picture = models.ForeignKey(
        Picture,
        verbose_name=u'Picture',
        help_text=u'Picture is included in this collection.',
    )
    collection = models.ForeignKey(
        Collection,
        verbose_name=u'Collection',
        help_text=u'Picture is included in this collection',
    )
    order = models.IntegerField(
        verbose_name=u'Order',
        help_text=u'What order to display this picture within the collection.',
        max_length=255
    )

    class Meta:
        verbose_name = u"Collection Picture"
        verbose_name_plural = u"Collection Pictures"
        ordering = ['order', ]

    def __unicode__(self):
        return self.picture.name + " is displayed in " + self.collection.name + (
        " in …

我使用的是 PostGres 10、Python 3.9 和 Django 3.2。我已经建立了这个模型以及伴随的多对多关系......

class Account(models.Model):    
    id = models.UUIDField(primary_key=True, default=uuid.uuid4, editable=False)
    ...
    crypto_currencies = models.ManyToManyField(CryptoCurrency)

生成并运行 Django 迁移后，创建了下表...

\d cbapp_account_crypto_currencies;
                               Table "public.cbapp_account_crypto_currencies"
      Column       |  Type   |                                  Modifiers                                   
-------------------+---------+------------------------------------------------------------------------------
 id                | integer | not null default nextval('cbapp_account_crypto_currencies_id_seq'::regclass)
 account_id        | uuid    | not null
 cryptocurrency_id | uuid    | not null
Indexes:
    "cbapp_account_crypto_currencies_pkey" PRIMARY KEY, btree (id)
    "cbapp_account_crypto_cur_account_id_cryptocurrenc_38c41c43_uniq" UNIQUE CONSTRAINT, btree (account_id, cryptocurrency_id)
    "cbapp_account_crypto_currencies_account_id_611c9b45" btree (account_id)
    "cbapp_account_crypto_currencies_cryptocurrency_id_685fb811" btree (cryptocurrency_id)
Foreign-key constraints:
    "cbapp_account_crypto_account_id_611c9b45_fk_cbapp_acc" FOREIGN KEY (account_id) REFERENCES cbapp_account(id) DEFERRABLE INITIALLY DEFERRED …