django.db.utils.ProgrammingError: 关系不存在

如何解决django.db.utils.ProgrammingError: 关系不存在

我使用 Postgres db 开发了一个部署在 DigitalOcean 的 Ubuntu 服务器上的 Django 应用程序。一切正常，没有任何问题，但今天添加新模型后，我收到此错误： relation "documents_app_document" does not exist 虽然我有这个模型，我的一些模型继承自 Document 模型。但不知何故它已从数据库中删除，现在我无法在迁移后将其添加回数据库。如何将该模型作为表再次添加到数据库中？

ps：但是我打开了名为“0001_initial.py”的迁移文件，里面有 migrations.CreateModel( name='Document'...

models.py：

class Document(models.Model):
    created_date = models.DateTimeField(default=timezone.Now,blank=True,null=True)
    added_by = CurrentUserField()
    purpose = models.CharField(blank=True,max_length=300,null=True)


    def __str__(self):
        return str(self.added_by)

class MedicalDocument(Document):
    policy_number = models.CharField(max_length=20,null=True)
    medical_institution = models.CharField(max_length=100,null=True) 

迁移错误：

Operations to perform:
  Unapply all migrations: documents_app
Running migrations:
  Rendering model states... DONE
  Unapplying documents_app.0001_initial...Traceback (most recent call last):
  File "/home/azersigorta/insuranceproject/env/lib/python3.5/site-packages/django/db/backends/utils.py",line 84,in _execute
    return self.cursor.execute(sql,params)
psycopg2.errors.UndefinedTable: relation "documents_app_document" does not exist


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

Traceback (most recent call last):
  File "manage.py",line 22,in <module>
    main()
  File "manage.py",line 18,in main
    execute_from_command_line(sys.argv)
  File "/home/azersigorta/insuranceproject/env/lib/python3.5/site-packages/django/core/management/__init__.py",line 381,in execute_from_command_line
    utility.execute()
  File "/home/azersigorta/insuranceproject/env/lib/python3.5/site-packages/django/core/management/__init__.py",line 375,in execute
    self.fetch_command(subcommand).run_from_argv(self.argv)
  File "/home/azersigorta/insuranceproject/env/lib/python3.5/site-packages/django/core/management/base.py",line 323,in run_from_argv
    self.execute(*args,**cmd_options)
  File "/home/azersigorta/insuranceproject/env/lib/python3.5/site-packages/django/core/management/base.py",line 364,in execute
    output = self.handle(*args,**options)
  File "/home/azersigorta/insuranceproject/env/lib/python3.5/site-packages/django/core/management/base.py",line 83,in wrapped
    res = handle_func(*args,**kwargs)
  File "/home/azersigorta/insuranceproject/env/lib/python3.5/site-packages/django/core/management/commands/migrate.py",line 234,in handle
    fake_initial=fake_initial,File "/home/azersigorta/insuranceproject/env/lib/python3.5/site-packages/django/db/migrations/executor.py",line 121,in migrate
    state = self._migrate_all_backwards(plan,full_plan,fake=fake)
  File "/home/azersigorta/insuranceproject/env/lib/python3.5/site-packages/django/db/migrations/executor.py",line 196,in _migrate_all_backwards
    self.unapply_migration(states[migration],migration,line 269,in unapply_migration
    state = migration.unapply(state,schema_editor)
  File "/home/azersigorta/insuranceproject/env/lib/python3.5/site-packages/django/db/migrations/migration.py",line 175,in unapply
    operation.database_backwards(self.app_label,schema_editor,from_state,to_state)
  File "/home/azersigorta/insuranceproject/env/lib/python3.5/site-packages/django/db/migrations/operations/fields.py",line 120,in database_backwards
    schema_editor.remove_field(from_model,from_model._Meta.get_field(self.name))
  File "/home/azersigorta/insuranceproject/env/lib/python3.5/site-packages/django/db/backends/base/schema.py",line 487,in remove_field
    self.execute(sql)
  File "/home/azersigorta/insuranceproject/env/lib/python3.5/site-packages/django/db/backends/base/schema.py",line 137,in execute
    cursor.execute(sql,params)
  File "/home/azersigorta/insuranceproject/env/lib/python3.5/site-packages/django/db/backends/utils.py",line 99,in execute
    return super().execute(sql,line 67,in execute
    return self._execute_with_wrappers(sql,params,many=False,executor=self._execute)
  File "/home/azersigorta/insuranceproject/env/lib/python3.5/site-packages/django/db/backends/utils.py",line 76,in _execute_with_wrappers
    return executor(sql,many,context)
  File "/home/azersigorta/insuranceproject/env/lib/python3.5/site-packages/django/db/backends/utils.py",params)
  File "/home/azersigorta/insuranceproject/env/lib/python3.5/site-packages/django/db/utils.py",line 89,in __exit__
    raise dj_exc_value.with_traceback(traceback) from exc_value
  File "/home/azersigorta/insuranceproject/env/lib/python3.5/site-packages/django/db/backends/utils.py",params)
django.db.utils.ProgrammingError: relation "documents_app_document" does not exist

解决方法

添加更改/添加新模型后，请始终确保运行 python manage.py makemigrations 和 python manage.py migrate。 如果由于任何原因（迁移树重新排列、数据库故障等）出现问题，您可以通过执行 python manage.py migrate {app_name} {migration_index} 来恢复到特定的迁移。 因此，在您的情况下，我建议您尝试 python manage.py migrate {app_name} zero，然后重新迁移回最新版本。 您可能还需要使用 --fake。