Django's inspectdb doesn't do ManyToManyField

So I just tested one thing, making the following tables.

# 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;

Which should be relations in terms of ManyToManyField. However, Djangos inspectdb looked at it as 5 models with tons of ForeignKeys. Doesn't Djangos inspectdb take ManyToManyFields into account, or is my databasemodel wrong?

Solution

Your database schema appears to be alright. However Django doesn't automatically create Many-To-Many fields as you have found out. The models for driverclass_event and ** driver_driverclass_event** are a so-called 'through' models. Normally you would also define ManyToManyField on both ends of the relationship and specify the correct 'through' model:

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)

Normally through models are used when you want to store information about the relationship, like the start date of the relationship or to refer to this relationship using a foreign key. In your example, you store which drivers have a relationship to a DriverClassEvent. So DriverClassEvent should have a model to be able to refer to it.

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')

Now you could drop the DriverDriverClassEvent as you don't store any data about that relationship, or refer to the relationship in other models. So the last example becomes*:

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

* Note that you don't have control over the field names, so those would have to match to Django's auto-generated field names.