我有一个笑话模型:
class Joke(models.Model):
...
date_created = models.DateTimeField(default=datetime.now, blank=True)
date_modified = models.DateTimeField(default=datetime.now, blank=True)
creator = models.OneToOneField(User, default=1)
现在，当我尝试迁移最后一行时，出现错误。基本上，我想将用户链接到 Joke 对象，并且由于我已经有一个数据库，因此我希望默认值为 1，即管理员用户的 ID(我检查过...)。 Makemigrations 工作得很好，但是当我尝试迁移时，我得到了这个:
Operations to perform:
Apply all migrations: jokes_app, sessions, contenttypes, auth, taggit, default, admin
Running migrations:
Rendering model states... DONE
Applying jokes_app.0008_auto_20160723_1559...Traceback (most recent call last):
File "/home/antoni4040/Documents/Jokes_Website/django-jokes/venv/lib/python3.4/site-packages/django/db/backends/utils.py", line 64, in execute
return self.cursor.execute(sql, params)
psycopg2.IntegrityError: duplicate key value violates unique constraint "jokes_app_joke_creator_id_key"
DETAIL: Key (creator_id)=(1) already exists.
The above exception was the direct cause of the following exception:
Traceback (most recent call last):
File "./manage.py", line 10, in <module>
execute_from_command_line(sys.argv)
File "/home/antoni4040/Documents/Jokes_Website/django-jokes/venv/lib/python3.4/site-packages/django/core/management/__init__.py", line 353, in execute_from_command_line
utility.execute()
File "/home/antoni4040/Documents/Jokes_Website/django-jokes/venv/lib/python3.4/site-packages/django/core/management/__init__.py", line 345, in execute
self.fetch_command(subcommand).run_from_argv(self.argv)
File "/home/antoni4040/Documents/Jokes_Website/django-jokes/venv/lib/python3.4/site-packages/django/core/management/base.py", line 348, in run_from_argv
self.execute(*args, **cmd_options)
File "/home/antoni4040/Documents/Jokes_Website/django-jokes/venv/lib/python3.4/site-packages/django/core/management/base.py", line 399, in execute
output = self.handle(*args, **options)
File "/home/antoni4040/Documents/Jokes_Website/django-jokes/venv/lib/python3.4/site-packages/django/core/management/commands/migrate.py", line 200, in handle
executor.migrate(targets, plan, fake=fake, fake_initial=fake_initial)
File "/home/antoni4040/Documents/Jokes_Website/django-jokes/venv/lib/python3.4/site-packages/django/db/migrations/executor.py", line 92, in migrate
self._migrate_all_forwards(plan, full_plan, fake=fake, fake_initial=fake_initial)
File "/home/antoni4040/Documents/Jokes_Website/django-jokes/venv/lib/python3.4/site-packages/django/db/migrations/executor.py", line 121, in _migrate_all_forwards
state = self.apply_migration(state, migration, fake=fake, fake_initial=fake_initial)
File "/home/antoni4040/Documents/Jokes_Website/django-jokes/venv/lib/python3.4/site-packages/django/db/migrations/executor.py", line 198, in apply_migration
state = migration.apply(state, schema_editor)
File "/home/antoni4040/Documents/Jokes_Website/django-jokes/venv/lib/python3.4/site-packages/django/db/migrations/migration.py", line 123, in apply
operation.database_forwards(self.app_label, schema_editor, old_state, project_state)
File "/home/antoni4040/Documents/Jokes_Website/django-jokes/venv/lib/python3.4/site-packages/django/db/migrations/operations/fields.py", line 201, in database_forwards
schema_editor.alter_field(from_model, from_field, to_field)
File "/home/antoni4040/Documents/Jokes_Website/django-jokes/venv/lib/python3.4/site-packages/django/db/backends/base/schema.py", line 482, in alter_field
old_db_params, new_db_params, strict)
File "/home/antoni4040/Documents/Jokes_Website/django-jokes/venv/lib/python3.4/site-packages/django/db/backends/postgresql/schema.py", line 110, in _alter_field
new_db_params, strict,
File "/home/antoni4040/Documents/Jokes_Website/django-jokes/venv/lib/python3.4/site-packages/django/db/backends/base/schema.py", line 644, in _alter_field
[new_default],
File "/home/antoni4040/Documents/Jokes_Website/django-jokes/venv/lib/python3.4/site-packages/django/db/backends/base/schema.py", line 110, in execute
cursor.execute(sql, params)
File "/home/antoni4040/Documents/Jokes_Website/django-jokes/venv/lib/python3.4/site-packages/django/db/backends/utils.py", line 79, in execute
return super(CursorDebugWrapper, self).execute(sql, params)
File "/home/antoni4040/Documents/Jokes_Website/django-jokes/venv/lib/python3.4/site-packages/django/db/backends/utils.py", line 64, in execute
return self.cursor.execute(sql, params)
File "/home/antoni4040/Documents/Jokes_Website/django-jokes/venv/lib/python3.4/site-packages/django/db/utils.py", line 95, in __exit__
six.reraise(dj_exc_type, dj_exc_value, traceback)
File "/home/antoni4040/Documents/Jokes_Website/django-jokes/venv/lib/python3.4/site-packages/django/utils/six.py", line 685, in reraise
raise value.with_traceback(tb)
File "/home/antoni4040/Documents/Jokes_Website/django-jokes/venv/lib/python3.4/site-packages/django/db/backends/utils.py", line 64, in execute
return self.cursor.execute(sql, params)
django.db.utils.IntegrityError: duplicate key value violates unique constraint "jokes_app_joke_creator_id_key"
DETAIL: Key (creator_id)=(1) already exists.
我真的不明白出了什么问题。有任何想法吗？
最佳答案
OneToOne 字段强制执行，正如它的名字所说，一对一的关系，在你的情况下，这意味着一个用户可以成为一个而且只有一个笑话的创造者 - 绝对不是你想要的。使用 ForeignKey 代替:
creator = models.ForeignKey(User, default=1, on_delete=models.SET_DEFAULT)
关于python - Django:重复的键值违反了唯一约束，我们在Stack Overflow上找到一个类似的问题：https://stackoverflow.com/questions/38543752/