Django的inspectdb不执行ManyToManyField

Question

所以我只测试了一件东西，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;

哪个应该是关系ManyToManyField。但是，将Djangos inspectdb其视为带有外键吨的5种型号。不Djangos inspectdb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还不错。但是，Django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，您还将在关系的两端定义ManyToManyField并指定正确的“直通”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，当您要存储有关关系的信息（例如关系的开始日期或使用外键引用此关系）时，将使用贯穿模型。在您的示例中，存储哪些驱动程序与DriverClassEvent有关系。因此，DriverClassEvent应该具有一个能够引用它的模型。

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，或者在其他模型中引用该关系。因此，最后一个示例变为*：

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，因此它们必须与Django的自动生成的字段名称匹配。