在 Django 中迁移 easy_thumbnails 从 1.6.7 升级到 1.7.1

Question

我正在尝试从 Django 1.6.7 升级到 1.7.1

但是，在我的本地 virtualenv 和我自己的所有 Django 应用程序（新的 migrate 工作）中升级 Django 版本后，我无法将 easy_thumbnails 应用程序（2.2 版）的 migrate 升级到工作。此版本应该可以与 Django 1.7 中的新迁移系统（南后）一起正常工作（说明 here）。

据我所知，原因是easy_thumbnails 应用程序中的第二次迁移正在尝试重新创建迁移（源代码here）。

但是很自然，由于这个代码是包作者故意放在那里的，恐怕我自己做错了什么。

任何想法这是什么原因？

完整的堆栈跟踪：

./manage.py migrate easy_thumbnails --settings=[my.settings.module]
Operations to perform:
  Apply all migrations: easy_thumbnails
Running migrations:
  Applying easy_thumbnails.0002_thumbnaildimensions...Traceback (most recent call last):
  File "./manage.py", line 10, in <module>
    execute_from_command_line(sys.argv)
  File "/usr/local/virtualenvs/fsenv/local/lib/python2.7/site-packages/django/core/management/__init__.py", line 385, in execute_from_command_line
    utility.execute()
  File "/usr/local/virtualenvs/fsenv/local/lib/python2.7/site-packages/django/core/management/__init__.py", line 377, in execute
    self.fetch_command(subcommand).run_from_argv(self.argv)
  File "/usr/local/virtualenvs/fsenv/local/lib/python2.7/site-packages/django/core/management/base.py", line 288, in run_from_argv
    self.execute(*args, **options.__dict__)
  File "/usr/local/virtualenvs/fsenv/local/lib/python2.7/site-packages/django/core/management/base.py", line 338, in execute
    output = self.handle(*args, **options)
  File "/usr/local/virtualenvs/fsenv/local/lib/python2.7/site-packages/django/core/management/commands/migrate.py", line 160, in handle
    executor.migrate(targets, plan, fake=options.get("fake", False))
  File "/usr/local/virtualenvs/fsenv/local/lib/python2.7/site-packages/django/db/migrations/executor.py", line 63, in migrate
    self.apply_migration(migration, fake=fake)
  File "/usr/local/virtualenvs/fsenv/local/lib/python2.7/site-packages/django/db/migrations/executor.py", line 97, in apply_migration
    migration.apply(project_state, schema_editor)
  File "/usr/local/virtualenvs/fsenv/local/lib/python2.7/site-packages/django/db/migrations/migration.py", line 107, in apply
    operation.database_forwards(self.app_label, schema_editor, project_state, new_state)
  File "/usr/local/virtualenvs/fsenv/local/lib/python2.7/site-packages/django/db/migrations/operations/models.py", line 36, in database_forwards
    schema_editor.create_model(model)
  File "/usr/local/virtualenvs/fsenv/local/lib/python2.7/site-packages/django/db/backends/schema.py", line 263, in create_model
    self.execute(sql, params)
  File "/usr/local/virtualenvs/fsenv/local/lib/python2.7/site-packages/django/db/backends/schema.py", line 99, in execute
    cursor.execute(sql, params)
  File "/usr/local/virtualenvs/fsenv/local/lib/python2.7/site-packages/django/db/backends/utils.py", line 81, in execute
    return super(CursorDebugWrapper, self).execute(sql, params)
  File "/usr/local/virtualenvs/fsenv/local/lib/python2.7/site-packages/django/db/backends/utils.py", line 65, in execute
    return self.cursor.execute(sql, params)
  File "/usr/local/virtualenvs/fsenv/local/lib/python2.7/site-packages/django/db/utils.py", line 94, in __exit__
    six.reraise(dj_exc_type, dj_exc_value, traceback)
  File "/usr/local/virtualenvs/fsenv/local/lib/python2.7/site-packages/django/db/backends/utils.py", line 65, in execute
    return self.cursor.execute(sql, params)
django.db.utils.ProgrammingError: relation "easy_thumbnails_thumbnaildimensions" already exists

Answer 1

按照以下步骤解决了上述问题。

1. 在虚拟环境中恢复到以前的 Django 版本 (1.6.7)
2. 恢复到以前的代码版本（使用 South 迁移，而不是 Django 迁移）
3. 使用以下命令恢复上次应用的easy_thumbnails迁移（迁移0016）：

python manage.py migrate easy_thumbnails 0015 --settings=[your.settings.module]
 - Soft matched migration 0015 to 0015_auto__del_unique_thumbnail_name_storage_hash__add_unique_thumbnail_sou.
Running migrations for easy_thumbnails:
 - Migrating backwards to just after 0015_auto__del_unique_thumbnail_name_storage_hash__add_unique_thumbnail_sou.
 < easy_thumbnails:0016_auto__add_thumbnaildimensions

4. 在虚拟环境中恢复 Django 1.7.1（使用 pip install Django==1.7.1）
5. 运行新的migrate；现在应该可以工作了

Answer 2

实际上你可以在迁移前删除表：

./manage.py dbshell

# in db console run:
DROP TABLE easy_thumbnails_thumbnaildimensions;