The definition of ForeignKey of abstract base class in Django

Class base (models. Model):    user = models. ForeignKey (User)        class Meta:         abstract =true

The above is the definition of an abstract base class, with only one public field user,

Class A (Base):    Applier = models. ForeignKey (User)

Then there will be an error, as follows:

Commanderror:one or more models didn't validate:core.a:accessor for field ' user ' clashes with related field ' User.a_set ‘. Add a related_name argument to the definition for ' user '. Core.a:accessor for field ' applier ' Clashes with related field ' User.a_set '. Add a related_name argument to the definition for ' applier '.

A simple translation is: an object of Class A has two associated fields pointing to the same user class. and the association name is the same, all A_set

The solution is to avoid conflicts. By default, the name of the associated object is the lowercase object name plus ' _set '. Therefore, the specified related_name is displayed to resolve this issue.

Method One, in the subclass of the relevant reference to the same class in the field, add the Related_name attribute, as follows:

Class A (Base):    Applier = models. ForeignKey (User, related_name= ' Some_other_set ')

However, this action is too large (each subclass is modified), so it is best to add flexible support in the abstract base class, as follows:

Method Two:

Class base (models. Model):    user = models. ForeignKey (User, related_name = ' base_% (app_label) s_% (Class) s ')        class Meta:         abstract =true

This does not necessarily mean that you can avoid naming conflicts by 100%. If the subclass has other fields that are exactly foreignkey to user, and its Related_name property is set to ' base_% (App_label) s_% (Class) s ', there is a problem, but the probability is minimal.

Note that App_label seems to be no longer supported since 1.7.

The definition of ForeignKey of abstract base class in Django