python - python mysql django中的迁移错误

Question

在运行 python manage.py migrate 时出现此错误，如果我删除已经存在的表，此命令仍然显示此类错误

Apply all migrations: admin, auth, bridge, contenttypes, sessions
Running migrations:
  Applying contenttypes.0001_initial...Traceback (most recent call last):
  File "/usr/share/nginx/html/django_env/lib/python3.4/site-packages/django/db/backends/utils.py", line 83, in _execute
    return self.cursor.execute(sql)
  File "/usr/share/nginx/html/django_env/lib/python3.4/site-packages/django/db/backends/mysql/base.py", line 71, in execute
    return self.cursor.execute(query, args)
  File "/usr/share/nginx/html/django_env/lib/python3.4/site-packages/MySQLdb/cursors.py", line 250, in execute
    self.errorhandler(self, exc, value)
  File "/usr/share/nginx/html/django_env/lib/python3.4/site-packages/MySQLdb/connections.py", line 50, in defaulterrorhandler
    raise errorvalue
  File "/usr/share/nginx/html/django_env/lib/python3.4/site-packages/MySQLdb/cursors.py", line 247, in execute
    res = self._query(query)
  File "/usr/share/nginx/html/django_env/lib/python3.4/site-packages/MySQLdb/cursors.py", line 411, in _query
    rowcount = self._do_query(q)
  File "/usr/share/nginx/html/django_env/lib/python3.4/site-packages/MySQLdb/cursors.py", line 374, in _do_query
    db.query(q)
  File "/usr/share/nginx/html/django_env/lib/python3.4/site-packages/MySQLdb/connections.py", line 277, in query
    _mysql.connection.query(self, query)
_mysql_exceptions.OperationalError: (1050, "Table 'django_content_type' already exists")

上述异常是以下异常的直接原因：

Traceback (most recent call last):
  File "manage.py", line 15, in <module>
    execute_from_command_line(sys.argv)
  File "/usr/share/nginx/html/django_env/lib/python3.4/site-packages/django/core/management/__init__.py", line 371, in execute_from_command_line
    utility.execute()
  File "/usr/share/nginx/html/django_env/lib/python3.4/site-packages/django/core/management/__init__.py", line 365, in execute
    self.fetch_command(subcommand).run_from_argv(self.argv)
  File "/usr/share/nginx/html/django_env/lib/python3.4/site-packages/django/core/management/base.py", line 288, in run_from_argv
    self.execute(*args, **cmd_options)
  File "/usr/share/nginx/html/django_env/lib/python3.4/site-packages/django/core/management/base.py", line 335, in execute
    output = self.handle(*args, **options)
  File "/usr/share/nginx/html/django_env/lib/python3.4/site-packages/django/core/management/commands/migrate.py", line 200, in handle
    fake_initial=fake_initial,
  File "/usr/share/nginx/html/django_env/lib/python3.4/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 "/usr/share/nginx/html/django_env/lib/python3.4/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 "/usr/share/nginx/html/django_env/lib/python3.4/site-packages/django/db/migrations/executor.py", line 244, in apply_migration
    state = migration.apply(state, schema_editor)
  File "/usr/share/nginx/html/django_env/lib/python3.4/site-packages/django/db/migrations/migration.py", line 122, in apply
    operation.database_forwards(self.app_label, schema_editor, old_state, project_state)
  File "/usr/share/nginx/html/django_env/lib/python3.4/site-packages/django/db/migrations/operations/models.py", line 92, in database_forwards
    schema_editor.create_model(model)
  File "/usr/share/nginx/html/django_env/lib/python3.4/site-packages/django/db/backends/base/schema.py", line 314, in create_model
    self.execute(sql, params or None)
  File "/usr/share/nginx/html/django_env/lib/python3.4/site-packages/django/db/backends/base/schema.py", line 133, in execute
    cursor.execute(sql, params)
  File "/usr/share/nginx/html/django_env/lib/python3.4/site-packages/django/db/backends/utils.py", line 100, in execute
    return super().execute(sql, params)
  File "/usr/share/nginx/html/django_env/lib/python3.4/site-packages/django/db/backends/utils.py", line 68, in execute
    return self._execute_with_wrappers(sql, params, many=False, executor=self._execute)
  File "/usr/share/nginx/html/django_env/lib/python3.4/site-packages/django/db/backends/utils.py", line 77, in _execute_with_wrappers
    return executor(sql, params, many, context)
  File "/usr/share/nginx/html/django_env/lib/python3.4/site-packages/django/db/backends/utils.py", line 85, in _execute
    return self.cursor.execute(sql, params)
  File "/usr/share/nginx/html/django_env/lib/python3.4/site-packages/django/db/utils.py", line 89, in __exit__
    raise dj_exc_value.with_traceback(traceback) from exc_value
  File "/usr/share/nginx/html/django_env/lib/python3.4/site-packages/django/db/backends/utils.py", line 83, in _execute
    return self.cursor.execute(sql)
  File "/usr/share/nginx/html/django_env/lib/python3.4/site-packages/django/db/backends/mysql/base.py", line 71, in execute
    return self.cursor.execute(query, args)
  File "/usr/share/nginx/html/django_env/lib/python3.4/site-packages/MySQLdb/cursors.py", line 250, in execute
    self.errorhandler(self, exc, value)
  File "/usr/share/nginx/html/django_env/lib/python3.4/site-packages/MySQLdb/connections.py", line 50, in defaulterrorhandler
    raise errorvalue
  File "/usr/share/nginx/html/django_env/lib/python3.4/site-packages/MySQLdb/cursors.py", line 247, in execute
    res = self._query(query)
  File "/usr/share/nginx/html/django_env/lib/python3.4/site-packages/MySQLdb/cursors.py", line 411, in _query
    rowcount = self._do_query(q)
  File "/usr/share/nginx/html/django_env/lib/python3.4/site-packages/MySQLdb/cursors.py", line 374, in _do_query
    db.query(q)
  File "/usr/share/nginx/html/django_env/lib/python3.4/site-packages/MySQLdb/connections.py", line 277, in query
    _mysql.connection.query(self, query)
django.db.utils.OperationalError: (1050, "Table 'django_content_type' already exists")

标签： pythondjango

Answer 1

出于某种原因，Django 认为该表仍然存在。这里有几件事要做：

1. 确保从数据库中的迁移表中删除任何提及迁移的行。
2. 确保您的表实际上已被删除，而不是简单地清除
3. 重新运行python manage.py makemigrations和python manage.py migrate。
4. 通常，由于您使用的是 Django 的 ORM，因此请尽量不要手动从数据库中编辑或删除表，因为这可能会使 Django 崩溃。而是删除相关模型（或将模型标记为不使用数据库的抽象模型）