python - 尽管单元测试正常运行，Authtoken 迁移仍无法正常工作

Question

我正在添加TokenAuthentication到我们的 Django 项目。一切都很顺利，我已经为 token 身份验证添加了迁移和单元测试:

# Migration
from django.db import migrations


def create_missing_tokens(apps, schema_editor):
    """
    Tokens were added in 0002_auto_20160226_1747, we thus need to populate
    the tokens table for existing users
    """
    Token = apps.get_model('authtoken', 'Token')
    User = apps.get_model('accounts', 'CustomUser')
    for user in User.objects.all():
        Token.objects.get_or_create(user=user)


class Migration(migrations.Migration):

    dependencies = [
        # depends on authtoken migration
        ('accounts', '0003_subscription_max_updates_per_day'),
        ('authtoken', '0002_auto_20160226_1747'), # latest migration in the authtoken package
    ]
    operations = [
        migrations.RunPython(create_missing_tokens, reverse_code=migrations.RunPython.noop),
    ]

# unit test
class MigrationTestCase(TransactionTestCase):
    '''A Test case for testing migrations'''

    # These must be defined by subclasses.
    migrate_from = None
    migrate_to = None

    def setUp(self):
        super(MigrationTestCase, self).setUp()

        self.executor = MigrationExecutor(connection)
        self.executor.migrate(self.migrate_from)

    def migrate_to_dest(self):
        self.executor.loader.build_graph()  # reload.
        self.executor.migrate(self.migrate_to)

    @property
    def old_apps(self):
        return self.executor.loader.project_state(self.migrate_from).apps

    @property
    def new_apps(self):
        return self.executor.loader.project_state(self.migrate_to).apps

from accounts.models import CustomUserManager
class SummaryTestCase(MigrationTestCase):
    """
    We need to test that data is populated in the summary field on running the migration
    """

    migrate_from = [('accounts', '0003_subscription_max_updates_per_day')]
    migrate_to = [('accounts', '0004_create_tokens')]

    def setup_before_migration(self):
        manager = CustomUserManager()
        User = self.old_apps.get_model('accounts', 'CustomUser')
        manager.model = User
        manager.create_user(email='contact@a.fr',  # nosec
                            password='kjnfrkj',
)

    def test_token_populated(self):
        # runs setup
        self.setup_before_migration()

        # now migrate
        self.migrate_to_dest()

        # grab new models
        Token = self.new_apps.get_model('authtoken', 'Token')
        User = self.new_apps.get_model('accounts', 'CustomUser')
        for user in User.objects.all():
            self.assertTrue(Token.objects.filter(user_id=user.pk).exists())

这很好用，但是当我实际运行迁移时，我收到消息:

django.db.utils.IntegrityError: duplicate key value violates unique constraint "authtoken_token_pkey" DETAIL: Key (key)=() already exists.

这里是一些伪代码，说明了我所说的“实际运行迁移”:

$ git checkout <old commit>          # grab old commit
$ ./run.sh go                        # spin up docker with server and db
$ git checkout master                # which includes migrations
$ ./run.sh again                     # log into docker image with django
$ (docker) python manage.py migrate  # run the migrations

我看到的错误是这样的(问题末尾的完整堆栈跟踪):

django.db.utils.IntegrityError: duplicate key value violates unique constraint "authtoken_token_pkey"
DETAIL:  Key (key)=() already exists.

我无法理解使用Token.objects.get_or_create(user=user)的迁移如何获得重复的 key ？任何帮助将不胜感激

  Applying accounts.0004_create_tokens...Traceback (most recent call last):
  File "/usr/local/lib/python3.6/site-packages/django/db/models/query.py", line 538, in get_or_create
    return self.get(**kwargs), False
  File "/usr/local/lib/python3.6/site-packages/django/db/models/query.py", line 408, in get
    self.model._meta.object_name
__fake__.DoesNotExist: Token matching query does not exist.

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
  File "/usr/local/lib/python3.6/site-packages/django/db/backends/utils.py", line 84, in _execute
    return self.cursor.execute(sql, params)
psycopg2.errors.UniqueViolation: duplicate key value violates unique constraint "authtoken_token_pkey"
DETAIL:  Key (key)=() already exists.


The above exception was the direct cause of the following exception:

Traceback (most recent call last):
  File "manage.py", line 15, in <module>
    execute_from_command_line(sys.argv)
  File "/usr/local/lib/python3.6/site-packages/django/core/management/__init__.py", line 381, in execute_from_command_line
    utility.execute()
  File "/usr/local/lib/python3.6/site-packages/django/core/management/__init__.py", line 375, in execute
    self.fetch_command(subcommand).run_from_argv(self.argv)
  File "/usr/local/lib/python3.6/site-packages/django/core/management/base.py", line 323, in run_from_argv
    self.execute(*args, **cmd_options)
  File "/usr/local/lib/python3.6/site-packages/django/core/management/base.py", line 364, in execute
    output = self.handle(*args, **options)
  File "/usr/local/lib/python3.6/site-packages/django/core/management/base.py", line 83, in wrapped
    res = handle_func(*args, **kwargs)
  File "/usr/local/lib/python3.6/site-packages/django/core/management/commands/migrate.py", line 234, in handle
    fake_initial=fake_initial,
  File "/usr/local/lib/python3.6/site-packages/django/db/migrations/executor.py", line 117, in migrate
    state = self._migrate_all_forwards(state, plan, full_plan, fake=fake, fake_initial=fake_initial)
  File "/usr/local/lib/python3.6/site-packages/django/db/migrations/executor.py", line 147, in _migrate_all_forwards
    state = self.apply_migration(state, migration, fake=fake, fake_initial=fake_initial)
  File "/usr/local/lib/python3.6/site-packages/django/db/migrations/executor.py", line 245, in apply_migration
    state = migration.apply(state, schema_editor)
  File "/usr/local/lib/python3.6/site-packages/django/db/migrations/migration.py", line 124, in apply
    operation.database_forwards(self.app_label, schema_editor, old_state, project_state)
  File "/usr/local/lib/python3.6/site-packages/django/db/migrations/operations/special.py", line 190, in database_forwards
    self.code(from_state.apps, schema_editor)
  File "/code/accounts/migrations/0004_create_tokens.py", line 12, in create_missing_tokens
    Token.objects.get_or_create(user=user)
  File "/usr/local/lib/python3.6/site-packages/django/db/models/manager.py", line 82, in manager_method
    return getattr(self.get_queryset(), name)(*args, **kwargs)
  File "/usr/local/lib/python3.6/site-packages/django/db/models/query.py", line 541, in get_or_create
    return self._create_object_from_params(kwargs, params)
  File "/usr/local/lib/python3.6/site-packages/django/db/models/query.py", line 583, in _create_object_from_params
    raise e
  File "/usr/local/lib/python3.6/site-packages/django/db/models/query.py", line 575, in _create_object_from_params
    obj = self.create(**params)
  File "/usr/local/lib/python3.6/site-packages/django/db/models/query.py", line 422, in create
    obj.save(force_insert=True, using=self.db)
  File "/usr/local/lib/python3.6/site-packages/django/db/models/base.py", line 741, in save
    force_update=force_update, update_fields=update_fields)
  File "/usr/local/lib/python3.6/site-packages/django/db/models/base.py", line 779, in save_base
    force_update, using, update_fields,
  File "/usr/local/lib/python3.6/site-packages/django/db/models/base.py", line 870, in _save_table
    result = self._do_insert(cls._base_manager, using, fields, update_pk, raw)
  File "/usr/local/lib/python3.6/site-packages/django/db/models/base.py", line 908, in _do_insert
    using=using, raw=raw)
  File "/usr/local/lib/python3.6/site-packages/django/db/models/manager.py", line 82, in manager_method
    return getattr(self.get_queryset(), name)(*args, **kwargs)
  File "/usr/local/lib/python3.6/site-packages/django/db/models/query.py", line 1186, in _insert
    return query.get_compiler(using=using).execute_sql(return_id)
  File "/usr/local/lib/python3.6/site-packages/django/db/models/sql/compiler.py", line 1335, in execute_sql
    cursor.execute(sql, params)
  File "/usr/local/lib/python3.6/site-packages/django/db/backends/utils.py", line 99, in execute
    return super().execute(sql, params)
  File "/usr/local/lib/python3.6/site-packages/django/db/backends/utils.py", line 67, in execute
    return self._execute_with_wrappers(sql, params, many=False, executor=self._execute)
  File "/usr/local/lib/python3.6/site-packages/django/db/backends/utils.py", line 76, in _execute_with_wrappers
    return executor(sql, params, many, context)
  File "/usr/local/lib/python3.6/site-packages/django/db/backends/utils.py", line 84, in _execute
    return self.cursor.execute(sql, params)
  File "/usr/local/lib/python3.6/site-packages/django/db/utils.py", line 89, in __exit__
    raise dj_exc_value.with_traceback(traceback) from exc_value
  File "/usr/local/lib/python3.6/site-packages/django/db/backends/utils.py", line 84, in _execute
    return self.cursor.execute(sql, params)
django.db.utils.IntegrityError: duplicate key value violates unique constraint "authtoken_token_pkey"
DETAIL:  Key (key)=() already exists.

编辑:自定义用户类没什么特别的，看起来像这样:

class CustomUser(AbstractUser):
    """
    Replace username by email as required and unique.
    """
    is_alphanumeric_or_dash = RegexValidator(r'^[0-9a-zA-Z\-]*$', 'Only alphanumeric and "-" characters are allowed.')

    # Hide username
    username = None

    # Overidde other fields
    email = models.EmailField(_('email address'), unique=True)
    first_name = models.CharField(_('first name'),
                                  max_length=100,
                                  blank=True,
                                  validators=[is_alphanumeric_or_dash])
    last_name = models.CharField(_('last name'),
                                 max_length=100,
                                 blank=True,
                                 validators=[is_alphanumeric_or_dash])

    # /!\ At some point, user should have a default subcription /!\
    subscription = models.ForeignKey(Subscription, on_delete=models.PROTECT, blank=True, null=True)
    # some other fields, but nothing special...
    USERNAME_FIELD = 'email'
    # Override the UserManager with our custom one (for objects creation)
    objects = CustomUserManager()

Answer 1

Token 的 key 通常由其 save() 方法生成。当您手动生成 token 但在迁移中通过 apps.get_model() 引用模型时，这很好，none of the custom model methods are available .

所以发生的情况是 token 是用空 key 生成的。第一个可以工作，但之后的所有都会生成此错误，因为 key 不是唯一的。

一个简单的解决方法是将 DRF 用于生成 key 的代码复制到迁移中。像这样的东西应该有效:

for user in User.objects.using(db_alias).all():
    key = binascii.hexlify(os.urandom(20)).decode()
    Token.objects.using(db_alias).get_or_create(user=user, key=key)