Django的數據庫遷移問題 - 缺少 「移民類」 錯誤

Question

我的models.py文件，

class Dag(models.Model): 
    dag_id = models.CharField(primary_key=True, max_length=250) 
    is_paused = models.IntegerField(blank=True, null=True) 
    is_subdag = models.IntegerField(blank=True, null=True) 
    is_active = models.IntegerField(blank=True, null=True) 
    last_scheduler_run = models.DateTimeField(blank=True, null=True) 
    last_pickled = models.DateTimeField(blank=True, null=True) 
    last_expired = models.DateTimeField(blank=True, null=True) 
    scheduler_lock = models.IntegerField(blank=True, null=True) 
    pickle_id = models.IntegerField(blank=True, null=True) 
    fileloc = models.CharField(blank=True, max_length=250) 
    owners = models.CharField(blank=True, max_length=250) 

    def _str_(self): 
     return self.dag_id 

    class Meta: 
     managed = True 
     db_table = 'dag' 

我serializers.py文件，

class Dag_api_serializers(ModelSerializer): 
class Meta: 
    model = Dag 
    fields = ('dag_id','is_paused','is_active','is_subdag','last_scheduler_run','last_pickled','last_expired','scheduler_lock','pickle_id','fileloc','owners') 

同時給予條命令python manage.py migrate或makemigrations下面這樣的錯誤發生。我在我的車型之一db表，我希望他們通過這個命令遷移......在這裏我提到的錯誤消息的最後幾行

Traceback (most recent call last): 
    File "manage.py", line 22, in <module> 
    execute_from_command_line(sys.argv) 
    File "C:\env\lib\site-packages\django\core\management\__init__.py", line 363, in execute_from_command_line 
    utility.execute() 
    File "C:\env\lib\site-packages\django\core\management\__init__.py", line 355, in execute 
    self.fetch_command(subcommand).run_from_argv(self.argv) 
    File "C:\env\lib\site-packages\django\core\management\base.py", line 283, in run_from_argv 
    self.execute(*args, **cmd_options) 
    File "C:\env\lib\site-packages\django\core\management\base.py", line 330, in execute 
    output = self.handle(*args, **options) 
    File "C:\env\lib\site-packages\django\core\management\commands\makemigrations.py", line 96, in handle 
    loader = MigrationLoader(None, ignore_no_migrations=True) 
    File "C:\env\lib\site-packages\django\db\migrations\loader.py", line 52, in __init__ 
    self.build_graph() 
    File "C:\env\lib\site-packages\django\db\migrations\loader.py", line 203, in build_graph 
    self.load_disk() 
    File "C:\env\lib\site-packages\django\db\migrations\loader.py", line 117, in load_disk 
    "Migration %s in app %s has no Migration class" % (migration_name, app_config.label) 
django.db.migrations.exceptions.BadMigrationError: Migration serializers in app snippets has no Migration class 

在模型我指的是已經存在的表格。

Answer 1

查看Django docs for Migrations，特別是遷移文件的格式。沒有看到你的遷移代碼（你在評論中說你手動編寫），我猜遷移沒有被正確聲明。

錯誤是告訴你，你的應用程序（稱爲'snippets'）中的遷移（'serializers'）沒有遷移類，因此無法處理遷移。如果您按照文檔並正確聲明遷移，那麼它可能會解決您的問題。

從當前的文檔（1.11）：

Django就在加載時遷移文件（如一個Python模塊）對什麼是django.db.migrations.Migration的子類，稱爲遷移。然後，檢查這個對象的四個屬性，其中只有兩個是最常用的時間...

EG：

from django.db import migrations, models 

class Migration(migrations.Migration): 

    dependencies = [('migrations', '0001_initial')] 

    operations = [ 
     migrations.DeleteModel('Tribble'), 
     migrations.AddField('Author', 'rating', models.IntegerField(default=0)), 
    ]