Question

所以我只测试了一件事，制作了下表。

# Dump of table driverclass
# ------------------------------------------------------------

CREATE TABLE `driverclass` (
  `id` int(11) unsigned NOT NULL AUTO_INCREMENT,
  `name` varchar(20) DEFAULT NULL,
  PRIMARY KEY (`id`)
) ENGINE=InnoDB DEFAULT CHARSET=latin1;

# Dump of table event
# ------------------------------------------------------------

CREATE TABLE `event` (
  `id` int(11) unsigned NOT NULL AUTO_INCREMENT,
  `name` varchar(20) DEFAULT NULL,
  PRIMARY KEY (`id`)
) ENGINE=InnoDB DEFAULT CHARSET=latin1;

# Dump of table driver
# ------------------------------------------------------------

CREATE TABLE `driver` (
  `id` int(11) unsigned NOT NULL AUTO_INCREMENT,
  `name` varchar(20) DEFAULT NULL,
  PRIMARY KEY (`id`)
) ENGINE=InnoDB DEFAULT CHARSET=latin1;

# Dump of table driver_driverclass_event
# ------------------------------------------------------------

CREATE TABLE `driver_driverclass_event` (
  `id` int(11) unsigned NOT NULL AUTO_INCREMENT,
  `driver_id` int(11) unsigned DEFAULT NULL,
  `event_class_id` int(11) unsigned DEFAULT NULL,
  PRIMARY KEY (`id`),
  KEY `driver_id` (`driver_id`),
  KEY `event_class_id` (`event_class_id`),
  CONSTRAINT `driver_driverclass_event_ibfk_2` FOREIGN KEY (`event_class_id`) REFERENCES `driverclass_event` (`id`),
  CONSTRAINT `driver_driverclass_event_ibfk_1` FOREIGN KEY (`driver_id`) REFERENCES `driver` (`id`)
) ENGINE=InnoDB DEFAULT CHARSET=latin1;

# Dump of table driverclass_event
# ------------------------------------------------------------

CREATE TABLE `driverclass_event` (
  `id` int(11) unsigned NOT NULL AUTO_INCREMENT,
  `event_id` int(11) unsigned DEFAULT NULL,
  `driverclass_id` int(11) unsigned DEFAULT NULL,
  PRIMARY KEY (`id`),
  KEY `event_id` (`event_id`),
  KEY `driverclass_id` (`driverclass_id`),
  CONSTRAINT `driverclass_event_ibfk_2` FOREIGN KEY (`driverclass_id`) REFERENCES `driverclass` (`id`),
  CONSTRAINT `driverclass_event_ibfk_1` FOREIGN KEY (`event_id`) REFERENCES `event` (`id`)
) ENGINE=InnoDB DEFAULT CHARSET=latin1;

哪个应该是ManyToManyField方面的关系。但是，Djangos inspectdb将其视为具有大量ForeignKeys的5个模型。 Djangos inspectdb不考虑ManyToManyFields，还是我的数据库模型错误？

Answer 1

您的数据库架构似乎没问题。但是，Django并不会像您发现的那样自动创建“多对多”字段。 driverclass_event 和** driver_driverclass_event **的模型是所谓的“直通”模型。通常，您还要在关系的两端定义 ManyToManyField ，并指定正确的“通过”模型：

class Event(db.Model):
    pass

class DriverClass(db.Model):
    events = db.ManyToManyField(Event, through='DriverClassEvent')

class DriverClassEvent(db.Model):
    driver_class = db.ForeignKeyField(DriverClass)
    event = db.ForeignKeyField(Event)

另请参阅：https://docs.djangoproject.com/en/dev/topics/db/models/#extra-fields-on-many-to-many-relationships

通常，当您希望存储关于关系的信息时，例如关系的开始日期或使用外键引用此关系时，将使用模型。在您的示例中，您存储哪些驱动程序与 DriverClassEvent 有关系。所以 DriverClassEvent 应该有一个模型才能引用它。

class DriverDriverClassEvent(db.Model):
    driver = db.ForeignKeyField(Driver)
    driver_class_event = db.ForeignKeyField(DriverClassEvent)

class Driver(db.Model):
    driver_class_events = db.ManyToManyField(DriverClassEvent, through='DriverDriverClassEvent')

现在您可以删除 DriverDriverClassEvent ，因为您不存储有关该关系的任何数据，或者参考其他模型中的关系。所以最后一个例子变成了*：

class Driver(db.Model):
    driver_class_events = db.ManyToManyField(DriverClassEvent, db_table='driver_driverclass_event')

*请注意，您无法控制字段名称，因此必须与Django自动生成的字段名称匹配。

Django的inspectdb没有执行ManyToManyField

1 个答案: