How to have two models reference each other Django

问题

I have the following code:

class Game(models.Model):
    title = models.CharField(max_length=50)
    summery = models.CharField(max_length=500)
    key = models.IntegerField()
    pin = models.CharField(max_length=12)
    complete = models.BooleanField()
    invite_sent = models.DateTimeField()
    on = models.ForeignKey(Member, blank = True) #<----


class Member(models.Model):
    email = models.CharField(max_length=100)
    color = models.CharField(max_length=11)
    game = models.ForeignKey(Game) #<----

The "on" foreign key links to one of the members (who's turn it is). All members of a game have their "game" foreign key set to the game they are on. The problem is that Django won't let me reference a class before it has been declared, and since I can't declare them simultaneously...

Edit: To clear things up, here's an example. If there were five members playing one game, all five would have foreign keys to the game. The game on the other hand would have one foreign key to the particular member who's turn it was.

回答1:

The Django documentation for the ForeignKey field states:

If you need to create a relationship on a model that has not yet been defined, you can use the name of the model, rather than the model object itself.

So in your case, that would be:

class Game(models.Model):
    # Other fields...
    on = models.ForeignKey('Member', blank = True)

class Member(models.Model):
    # Other fields...
    game = models.ForeignKey(Game)

回答2:

You don't need to have the two models reference each other with foreign keys. Remove the line:

on = models.ForeignKey(Member, blank = True) #<----

and logically your Member's will still be associated to different Game's (and this makes more sense because a member can belong to one game at a time, whereas a game can have more than one member).

You can use reverse relation to figure out which members are on a particular game.

来源：https://stackoverflow.com/questions/13978503/how-to-have-two-models-reference-each-other-django

标签

python

django

django-models

models