在数据库架构中进行了一些广泛的更改之后，我运行了16:39:22.181 PGSQL Resource "opentap @ localhost:5433" opened. [173 ms]
16:39:22.181 Summary ------ Summary of test plan started 09/10/2020 16:39:22 ------
16:39:22.181 Summary --------------------------------------------------------------
16:39:22.181 Summary ----- Test plan completed with verdict Error in 2.33 ms ------
16:39:22.210 PGSQL Error in OnTestPlanRunCompleted for 'opentap @ localhost:5433': '23503: insert or update on table "testrun2attachment" violates foreign key constraint "testrun2attachment_runid_fkey"'
16:39:22.216 PGSQL Resource "opentap @ localhost:5433" closed. [1.22 ms]
。它成功创建了迁移。但是随后makemigrations失败了：
migrate出了什么问题？
这是完整的追溯：
AttributeError: 'str' object has no attribute '_meta'
与这个问题有点类似：Django makemigrations AttributeError: 'str' object has no attribute '_meta'，但是我的$ ./manage.py migrate
Operations to perform:
Apply all migrations: account, admin, auth, clients, contenttypes, ...<snip>
Running migrations:
Applying clients.0004_auto_20200910_1241...Traceback (most recent call last):
File "./manage.py", line 21, in <module>
main()
File "./manage.py", line 17, in main
execute_from_command_line(sys.argv)
File "...<snip>.../lib/python3.8/site-packages/django/core/management/__init__.py", line 401, in execute_from_command_line
utility.execute()
File "...<snip>.../lib/python3.8/site-packages/django/core/management/__init__.py", line 395, in execute
self.fetch_command(subcommand).run_from_argv(self.argv)
File "...<snip>.../lib/python3.8/site-packages/django/core/management/base.py", line 330, in run_from_argv
self.execute(*args, **cmd_options)
File "...<snip>.../lib/python3.8/site-packages/django/core/management/base.py", line 371, in execute
output = self.handle(*args, **options)
File "...<snip>.../lib/python3.8/site-packages/django/core/management/base.py", line 85, in wrapped
res = handle_func(*args, **kwargs)
File "...<snip>.../lib/python3.8/site-packages/django/core/management/commands/migrate.py", line 243, in handle
post_migrate_state = executor.migrate(
File "...<snip>.../lib/python3.8/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 "...<snip>.../lib/python3.8/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 "...<snip>.../lib/python3.8/site-packages/django/db/migrations/executor.py", line 227, in apply_migration
state = migration.apply(state, schema_editor)
File "...<snip>.../lib/python3.8/site-packages/django/db/migrations/migration.py", line 124, in apply
operation.database_forwards(self.app_label, schema_editor, old_state, project_state)
File "...<snip>.../lib/python3.8/site-packages/django/db/migrations/operations/fields.py", line 236, in database_forwards
schema_editor.alter_field(from_model, from_field, to_field)
File "...<snip>.../lib/python3.8/site-packages/django/db/backends/sqlite3/schema.py", line 138, in alter_field
super().alter_field(model, old_field, new_field, strict=strict)
File "...<snip>.../lib/python3.8/site-packages/django/db/backends/base/schema.py", line 553, in alter_field
old_field.remote_field.through._meta.auto_created and
AttributeError: 'str' object has no attribute '_meta'
没问题，只在makemigrations命令下失败了。
答案 0 :(得分：0)
事实证明，在其中一个迁移中，以错误的顺序创建了2个更改：
through参数的已删除模型的M2M字段已更改（以使用其他“通过模型”）。从迁移文件中删除migrations.DeleteModel步骤可以解决此问题。
当然，我必须创建一个新的迁移，该迁移实际上会删除过时的模型，但是效果很好。
不确定仅移动迁移文件中迁移操作的顺序是否可以解决问题。
可能是Django中的错误，需要更多研究。