I am getting a field clash in my models:
class Visit(models.Model):
user = models.ForeignKey(User)
visitor = models.ForeignKey(User)
Error: One or more models did not validate:
profiles.visit: Accessor for field 'user' clashes with related field 'User.visit_set'. Add a related_name argument to the definition for 'user'.
profiles.visit: Accessor for field 'visitor' clashes with related field 'User.visit_set'. Add a related_name argument to the definition for 'visitor'.
what would be a sensible 开发者_高级运维 'related_field' to use on visitor field? This model basically represents the visits that take place to a particular user's profile.
Also should I replace any of the ForeignKey's with a ManyToManyField? The logic is a bit confusing.
Edit: This seems to fix it, but I am unsure if it's what I want. :)
class Visit(models.Model):
user = models.ForeignKey(User)
visitor = models.ForeignKey(User, related_name='visitors')
When you have a ForeignKey
, it creates a property named with the model name plus _set
to the referenced model. The problem here is that both foreign keys want to create a property on User
named visit_set
. The solution is to add related names that are different for each foreign key.
Usually, I use plurals for related names. In cases like these, I add an "as" clause to the related name:
class Visit(models.Model):
user = models.ForeignKey(User, related_name="visitsAsUser")
visitor = models.ForeignKey(User, related_name="visitsAsVisitor")
You don't want a ManyToManyField
unless you can have zero or more visitors per Visit
, or users per Visit
.
If a visit is a strong concept in your application, then it might make sense to have it the way you defined: visit consists of a 'user user' and a 'user visitor'.
If, however, a visit is just a way in which users relate among themselves, then perhaps you should have a ManyToMany
relation between users. For that purpose you should probably use ManyToManyField.symmetrical in a User Profile (in which you extend the information that comes with auth.models.User
).
In any case, regarding the related_name, you may either disable the backwards relation if you won't be accessing the visits from the user, or use a sensible name such as visits_to_self
on user
and visits_to_others
on visitor
, which would allow seeing who visited a user by calling user.visits_to_self
and who the user visited by user.visits_to_others
.
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