Python – In Django Admin, I want to change how foreign keys are displayed in a Many-Many Relationship admin widget

djangodjango-admindjango-widgetpython

I have a ManyToMany relationship:

class Book:
  title = models.CharField(...)
  isbn = models.CharField(...)

  def unicode(self):
    return self.title

  def ISBN(self):
    return self.isbn

class Author:
  name = models.CharField(...)
  books = models.ManyToManyField(Book...)

In the admin interface for Author I get a multiple select list that uses the unicode display for books. I want to change the list in two ways:

1) Only for the admin interface I want to display the ISBN number, everywhere else I just print out a "Book" object I want the title displayed.

2) How could I use a better widget than MultipleSelectList for the ManyToMany. How could I specify to use a CheckBoxSelectList instead?

Best Answer

To display the ISBN you could make a custom field like this:


class BooksField(forms.ModelMultipleChoiceField):
    def label_from_instance(self, obj):
        return obj.isbn

There's a CheckboxSelectMultiple for the ManyToManyField but it doesn't display correctly on the admin, so you could also write some css to fix that.

You need to create a form for the model, and use that in your admin class:


class AuthorForm(forms.ModelForm):
    books = BooksField(Book.objects.all(), widget=forms.CheckboxSelectMultiple)

    class Meta:
        model = Author

    class Media:
        css = {
            'all': ('booksfield.css',)
        }

class AuthorAdmin(admin.ModelAdmin):
    form = AuthorForm

Related Solutions

Go – Django Admin SelectMultiple Widget

In your form class, you can specify a custom queryset for the group-field, which then determines which Group-instances are available in the form:

class UserForm(forms.ModelForm):
    # override the default groups field
    groups = forms.ModelMultipleChoiceField(
        queryset=Groups.objects.filter(YOUR_CONDITIONS),
        widget=forms.SelectMultiple,
    )

    class Meta:
        model = User

Foreign keys in django admin list display

I was looking for a solution to the same problem and ran across this question... ended up solving it myself. The OP might not be interested anymore but this could still be useful to someone.

from functools import partial
from django.forms import MediaDefiningClass

class ModelAdminWithForeignKeyLinksMetaclass(MediaDefiningClass):

    def __getattr__(cls, name):

        def foreign_key_link(instance, field):
            target = getattr(instance, field)
            return u'<a href="../../%s/%s/%d">%s</a>' % (
                target._meta.app_label, target._meta.module_name, target.id, unicode(target))

        if name[:8] == 'link_to_':
            method = partial(foreign_key_link, field=name[8:])
            method.__name__ = name[8:]
            method.allow_tags = True
            setattr(cls, name, method)
            return getattr(cls, name)
        raise AttributeError

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

class BookAdmin(admin.ModelAdmin):
    __metaclass__ = ModelAdminWithForeignKeyLinksMetaclass

    list_display = ('title', 'link_to_author')

Replace 'partial' with Django's 'curry' if not using python >= 2.5.

Best Answer

Related Solutions

Go – Django Admin SelectMultiple Widget

Foreign keys in django admin list display

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