It seems there are a bit more on rails model associations.
https://docs.djangoproject.com/en/1.7/ref/models/fields/#mod...
In general:
Django's ForeignKey is equivalent to Rails' belongs_to.
Django's OneToOneField is equivalent to Rails' has_one.
Django's ManyToManyField is equivalent to Rails' has_and_belongs_to_many.
Also, in Django one generally only declares the relationship from one "side", unlike Rails where the relationship is declared on both "sides" (i.e., in Django one simply sets up a ForeignKey on A pointing to B, rather than placing relationship identifiers on both A and B).
The equivalent of ":through" is also available.
Django has GenericForeignKey as an equivalent to Rails' polymorphic associations.
> Also, in Django one generally only declares the relationship from one "side", unlike Rails where the relationship is declared on both "sides" (i.e., in Django one simply sets up a ForeignKey on A pointing to B, rather than placing relationship identifiers on both A and B).
That's because django will automatically add the reverse of the relation to B, so that you can access A through B. You can disable that functionality optionally though.
(My guess is Rails didn't use proper FKs by default because the default development db (SQLite) originally didn't support foreign keys (though it has for a while now, since 3.9.16), and they presumably wanted to minimise the differences in the way they use different databases).