decorators.py

from django.core.urlresolvers import reverse
from django.utils.text import mark_safe


def add_link_field_to_related(target_model=None, field='', app='', field_name='link',
                   link_text=unicode):
    def add_link(cls):
        reverse_name = target_model or cls.model.__name__.lower()

        def link(self, instance):
            app_name = app or instance._meta.app_label
            reverse_path = "admin:%s_%s_change" % (app_name, reverse_name)
            link_obj = getattr(instance, field, None) or instance
            url = reverse(reverse_path, args = (link_obj.id,))
            return mark_safe("<a href='%s'>%s</a>" % (url, link_text(link_obj)))
        link.allow_tags = True
        link.short_description = reverse_name + ' link'
        setattr(cls, field_name, link)
        cls.readonly_fields = list(getattr(cls, 'readonly_fields', [])) + \
            [field_name]
        return cls
    return add_link


def add_link_field_to_create_related(
    target_model=None,
    reverse_field='',
    app='',
    link_text=None,
    field_name='link',
    short_description=None
):
    def add_link(cls):
        reverse_name = target_model or cls.model.__name__.lower()

        def link(self, instance):
            app_name = app or instance._meta.app_label
            reverse_path = "admin:%s_%s_add" % (app_name, reverse_name)
            url = reverse(reverse_path)
            link_text_to_display = link_text or "Add %s to %s" % (reverse_name, instance)
            return mark_safe("<a href='%s?%s=%s'>%s</a>" % (url, reverse_field, instance.id, link_text_to_display))
        link.allow_tags = True
        link.short_description = short_description or 'Add %s link' % reverse_name
        setattr(cls, field_name, link)
        cls.readonly_fields = tuple(getattr(cls, 'readonly_fields', tuple())) + (field_name,)
        return cls
    return add_link