Trying to make a PostgreSQL field with a list of foreign keys in Django
You can't create an array of foreign keys. It is not a Django limitation, it is a PostgreSQL "limitation".
The reason is that a foreign key is not a type, it is a constraint on a field. An array of foreign keys does not make any sense.
The general approach to achieve this is to use an intermediate table that will be used as a link between two others :
Authors(id, name)
Books(id, title, pub_date)
BookAuthors(id, book_id, author_id)
In the above exemple, BookAuthors.book_id
is a foreign key to Books.id
and BookAuthors.author_id
is a foreign key to Authors.id
. Thus, the table BookAuthors
is used to match an author with a book and vice versa.
Django abstracts this intermediate table with ManyToManyField
fields:
class Authors(models.Model):
name = models.CharField(...)
class Books(models.Model):
title = models.CharField(...)
pub_date = models.DateField(...)
authors = models.ManyToManyField('my_app.Authors',
related_name='authored_books')
Behind the scenes, Django will create the intermediate table.
Then, you can get all authors of a book using book.authors.all()
, or all books authored by an author using author.authored_books.all()
.
You have to use ManyToManyField
, ArrayField
can't be related with another model.