admin list_filter values depending on other filters

Question

Let's take a look at this example:

class Author(models.Model):
    ...    

class Book(models.Model):
    author = models.ForeignKey(Author, related_name='books'...)
    ...

class Chapter(models.Model):
    book = models.ForeignKey(Book, related_name='chapters' ...)
    ...

For the admin, lets configure ChapterAdmin like so:

class ChapterAdmin(admin.ModelAdmin):
    list_filter = ('book__author', 'book',)
    ...

This gives nice filters by related Author and Book.

Here goes the question:

When user clicks on an Author in book__author filter, the results in main table get filtered accordingly. Good. But the book filter still lists all available Books, regardless of the book_author filter. Is there a way to make the book filter dependent of book__author filter such that when an Author is selected, only Books by that are related to the Author are listed in filter options?

Answer 1

Looks like you can use SimpleListFilter to do the job, since you have the request in the lookups method you can tell which author is selected and provide only a list of his books, more info in the doc: https://docs.djangoproject.com/en/1.4/ref/contrib/admin/#django.contrib.admin.ModelAdmin.list_filter