[python] Can "list_display" in a Django ModelAdmin display attributes of ForeignKey fields?

I have a Person model that has a foreign key relationship to Book, which has a number of fields, but I'm most concerned about author (a standard CharField).

With that being said, in my PersonAdmin model, I'd like to display book.author using list_display:

class PersonAdmin(admin.ModelAdmin):
    list_display = ['book.author',]

I've tried all of the obvious methods for doing so, but nothing seems to work.

Any suggestions?

You can show whatever you want in list display by using a callable. It would look like this:

def book_author(object):
  return object.book.author

class PersonAdmin(admin.ModelAdmin):
  list_display = [book_author,]

According to the documentation, you can only display the __unicode__ representation of a ForeignKey:

http://docs.djangoproject.com/en/dev/ref/contrib/admin/#list-display

Seems odd that it doesn't support the 'book__author' style format which is used everywhere else in the DB API.

Turns out there's a ticket for this feature, which is marked as Won't Fix.

AlexRobbins' answer worked for me, except that the first two lines need to be in the model (perhaps this was assumed?), and should reference self:

def book_author(self):
  return self.book.author

Then the admin part works nicely.

Like the rest, I went with callables too. But they have one downside: by default, you can't order on them. Fortunately, there is a solution for that:

Django >= 1.8

def author(self, obj):
    return obj.book.author
author.admin_order_field  = 'book__author'

Django < 1.8

def author(self):
    return self.book.author
author.admin_order_field  = 'book__author'

I prefer this:

class CoolAdmin(admin.ModelAdmin):
    list_display = ('pk', 'submodel__field')

    @staticmethod
    def submodel__field(obj):
        return obj.submodel.field

Despite all the great answers above and due to me being new to Django, I was still stuck. Here's my explanation from a very newbie perspective.

models.py

class Author(models.Model):
    name = models.CharField(max_length=255)

class Book(models.Model):
    author = models.ForeignKey(Author)
    title = models.CharField(max_length=255)

admin.py (Incorrect Way) - you think it would work by using 'model__field' to reference, but it doesn't

class BookAdmin(admin.ModelAdmin):
    model = Book
    list_display = ['title', 'author__name', ]

admin.site.register(Book, BookAdmin)

admin.py (Correct Way) - this is how you reference a foreign key name the Django way

class BookAdmin(admin.ModelAdmin):
    model = Book
    list_display = ['title', 'get_name', ]

    def get_name(self, obj):
        return obj.author.name
    get_name.admin_order_field  = 'author'  #Allows column order sorting
    get_name.short_description = 'Author Name'  #Renames column head

    #Filtering on side - for some reason, this works
    #list_filter = ['title', 'author__name']

admin.site.register(Book, BookAdmin)

For additional reference, see the Django model link here

You can show whatever you want in list display by using a callable. It would look like this:

def book_author(object):
  return object.book.author

class PersonAdmin(admin.ModelAdmin):
  list_display = [book_author,]

There is a very easy to use package available in PyPI that handles exactly that: django-related-admin. You can also see the code in GitHub.

Using this, what you want to achieve is as simple as:

class PersonAdmin(RelatedFieldAdmin):
    list_display = ['book__author',]

Both links contain full details of installation and usage so I won't paste them here in case they change.

Just as a side note, if you're already using something other than model.Admin (e.g. I was using SimpleHistoryAdmin instead), you can do this: class MyAdmin(SimpleHistoryAdmin, RelatedFieldAdmin).

If you have a lot of relation attribute fields to use in list_display and do not want create a function (and it's attributes) for each one, a dirt but simple solution would be override the ModelAdmin instace __getattr__ method, creating the callables on the fly:

class DynamicLookupMixin(object):
    '''
    a mixin to add dynamic callable attributes like 'book__author' which
    return a function that return the instance.book.author value
    '''

    def __getattr__(self, attr):
        if ('__' in attr
            and not attr.startswith('_')
            and not attr.endswith('_boolean')
            and not attr.endswith('_short_description')):

            def dyn_lookup(instance):
                # traverse all __ lookups
                return reduce(lambda parent, child: getattr(parent, child),
                              attr.split('__'),
                              instance)

            # get admin_order_field, boolean and short_description
            dyn_lookup.admin_order_field = attr
            dyn_lookup.boolean = getattr(self, '{}_boolean'.format(attr), False)
            dyn_lookup.short_description = getattr(
                self, '{}_short_description'.format(attr),
                attr.replace('_', ' ').capitalize())

            return dyn_lookup

        # not dynamic lookup, default behaviour
        return self.__getattribute__(attr)


# use examples    

@admin.register(models.Person)
class PersonAdmin(admin.ModelAdmin, DynamicLookupMixin):
    list_display = ['book__author', 'book__publisher__name',
                    'book__publisher__country']

    # custom short description
    book__publisher__country_short_description = 'Publisher Country'


@admin.register(models.Product)
class ProductAdmin(admin.ModelAdmin, DynamicLookupMixin):
    list_display = ('name', 'category__is_new')

    # to show as boolean field
    category__is_new_boolean = True

As gist here

Callable especial attributes like boolean and short_description must be defined as ModelAdmin attributes, eg book__author_verbose_name = 'Author name' and category__is_new_boolean = True.

The callable admin_order_field attribute is defined automatically.

Don't forget to use the list_select_related attribute in your ModelAdmin to make Django avoid aditional queries.

if you try it in Inline, you wont succeed unless:

in your inline:

class AddInline(admin.TabularInline):
    readonly_fields = ['localname',]
    model = MyModel
    fields = ('localname',)

in your model (MyModel):

class MyModel(models.Model):
    localization = models.ForeignKey(Localizations)

    def localname(self):
        return self.localization.name

I just posted a snippet that makes admin.ModelAdmin support '__' syntax:

http://djangosnippets.org/snippets/2887/

So you can do:

class PersonAdmin(RelatedFieldAdmin):
    list_display = ['book__author',]

This is basically just doing the same thing described in the other answers, but it automatically takes care of (1) setting admin_order_field (2) setting short_description and (3) modifying the queryset to avoid a database hit for each row.

This one's already accepted, but if there are any other dummies out there (like me) that didn't immediately get it from the presently accepted answer, here's a bit more detail.

The model class referenced by the ForeignKey needs to have a __unicode__ method within it, like here:

class Category(models.Model):
    name = models.CharField(max_length=50)

    def __unicode__(self):
        return self.name

That made the difference for me, and should apply to the above scenario. This works on Django 1.0.2.

Please note that adding the get_author function would slow the list_display in the admin, because showing each person would make a SQL query.

To avoid this, you need to modify get_queryset method in PersonAdmin, for example:

def get_queryset(self, request):
    return super(PersonAdmin,self).get_queryset(request).select_related('book')

Before: 73 queries in 36.02ms (67 duplicated queries in admin)

After: 6 queries in 10.81ms