Django迁移命令报错

Question

我收到迁移命令错误 --

django.db.utils.OperationalError: (1170, "BLOB/TEXT column 'module_name' used in key specification without a key length")

模型是

class Coupling(models.Model):
    coupling_name = models.CharField(max_length=150, blank=False, default=True, unique=True)
    module_name = models.TextField(max_length=255)

虽然有一个密钥长度。

Traceback (most recent call last):
  File "manage.py", line 22, in <module>
    execute_from_command_line(sys.argv)
  File "C:\virtualenvs\ciasenv\lib\site-packages\django\core\management\__init__.py", line 367, in execute_from_command_line
    utility.execute()
  File "C:\virtualenvs\ciasenv\lib\site-packages\django\core\management\__init__.py", line 359, in execute
    self.fetch_command(subcommand).run_from_argv(self.argv)
  File "C:\virtualenvs\ciasenv\lib\site-packages\django\core\management\base.py", line 294, in run_from_argv
    self.execute(*args, **cmd_options)
  File "C:\virtualenvs\ciasenv\lib\site-packages\django\core\management\base.py", line 345, in execute
    output = self.handle(*args, **options)
  File "C:\virtualenvs\ciasenv\lib\site-packages\django\core\management\commands\migrate.py", line 204, in handle
    fake_initial=fake_initial,
  File "C:\virtualenvs\ciasenv\lib\site-packages\django\db\migrations\executor.py", line 115, in migrate
    state = self._migrate_all_forwards(state, plan, full_plan, fake=fake, fake_initial=fake_initial)
  File "C:\virtualenvs\ciasenv\lib\site-packages\django\db\migrations\executor.py", line 145, in _migrate_all_forwards
    state = self.apply_migration(state, migration, fake=fake, fake_initial=fake_initial)
  File "C:\virtualenvs\ciasenv\lib\site-packages\django\db\migrations\executor.py", line 244, in apply_migration
    state = migration.apply(state, schema_editor)
  File "C:\virtualenvs\ciasenv\lib\site-packages\django\db\migrations\migration.py", line 129, in apply
    operation.database_forwards(self.app_label, schema_editor, old_state, project_state)
  File "C:\virtualenvs\ciasenv\lib\site-packages\django\db\migrations\operations\fields.py", line 204, in database_forwards
    schema_editor.alter_field(from_model, from_field, to_field)
  File "C:\virtualenvs\ciasenv\lib\site-packages\django\db\backends\base\schema.py", line 495, in alter_field
    old_db_params, new_db_params, strict)
  File "C:\virtualenvs\ciasenv\lib\site-packages\django\db\backends\base\schema.py", line 678, in _alter_field
    self.execute(self._create_unique_sql(model, [new_field.column]))
  File "C:\virtualenvs\ciasenv\lib\site-packages\django\db\backends\base\schema.py", line 112, in execute
    cursor.execute(sql, params)
  File "C:\virtualenvs\ciasenv\lib\site-packages\django\db\backends\utils.py", line 79, in execute
    return super(CursorDebugWrapper, self).execute(sql, params)
  File "C:\virtualenvs\ciasenv\lib\site-packages\django\db\backends\utils.py", line 64, in execute
    return self.cursor.execute(sql, params)
  File "C:\virtualenvs\ciasenv\lib\site-packages\django\db\utils.py", line 94, in __exit__
    six.reraise(dj_exc_type, dj_exc_value, traceback)
  File "C:\virtualenvs\ciasenv\lib\site-packages\django\utils\six.py", line 685, in reraise
    raise value.with_traceback(tb)
  File "C:\virtualenvs\ciasenv\lib\site-packages\django\db\backends\utils.py", line 64, in execute
    return self.cursor.execute(sql, params)
  File "C:\virtualenvs\ciasenv\lib\site-packages\django\db\backends\mysql\base.py", line 112, in execute
    return self.cursor.execute(query, args)
  File "C:\virtualenvs\ciasenv\lib\site-packages\MySQLdb\cursors.py", line 250, in execute
    self.errorhandler(self, exc, value)
  File "C:\virtualenvs\ciasenv\lib\site-packages\MySQLdb\connections.py", line 50, in defaulterrorhandler
    raise errorvalue
  File "C:\virtualenvs\ciasenv\lib\site-packages\MySQLdb\cursors.py", line 247, in execute
    res = self._query(query)
  File "C:\virtualenvs\ciasenv\lib\site-packages\MySQLdb\cursors.py", line 411, in _query
    rowcount = self._do_query(q)
  File "C:\virtualenvs\ciasenv\lib\site-packages\MySQLdb\cursors.py", line 374, in _do_query
    db.query(q)
  File "C:\virtualenvs\ciasenv\lib\site-packages\MySQLdb\connections.py", line 292, in query
    _mysql.connection.query(self, query)
django.db.utils.OperationalError: (1061, "Duplicate key name 'accounts_coupling_coupling_name_175325e1_uniq'")

非常感谢任何帮助。提前致谢。

Answer 1

第一个错误可能是因为您试图为 TextField 设置 unique=True。这对于 MySQL、as noted in the docs.

是不可能的

第二个错误是因为您试图创建一个已经存在的索引。这可能是因为您已经运行迁移，但它在中途失败了。 MySQL 不会运行在 t运行操作中更改架构，因此如果更改失败则不会回滚。您可以尝试手动删除索引，或者，如果这是一个新项目，删除数据库并重新开始可能会更容易。

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