Django - Model with 2 foreign keys from the same class
I wanted a Django model with 2 foreign keys from the same table. It's an event table which has 2 columns for employees: the 'home' and the 'away'. But I get this error: Err开发者_如何转开发or: One or more models did not validate...
class Team(models.Model):
name = models.CharField(max_length=200)
class Match(models.Model):
home = models.ForeignKey(Team)
away = models.ForeignKey(Team)
Any idea for this. Thanks!
Django follows relationship backwards, too. By default, it creates attribute match_set
on your Team
objects. Because you referenced Team
twice, you must distinguish those backwards attributes by providing related_name
attribute on ForeignKey
s.
class Match(models.Model):
home = models.ForeignKey(Team, related_name='home_set')
away = models.ForeignKey(Team, related_name='away_set')
Change the Match
model to use related_name
.
class Match(models.Model):
home = models.ForeignKey(Team, related_name="home_set")
away = models.ForeignKey(Team, related_name="away_set")
The documentation has this to say about related_name
:
The name to use for the relation from the related object back to this one.
You are getting the error because from the Team
side there will be two relations and they will both have the name, viz. match
. You'll refer to this from the Team
side using team.match_set
. By changing the related_name
of the second FK you are fixing this.
Update
As @Török Gábor said, you can now use team.home_set
and team.away_set
respectively.
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