Django: adding an “Add new” button for a ForeignKey in a ModelForm

Question

TL;DR: How can I add an \"Add new\" button for a ForeignKey in a ModelForm?

Long version: I\'m using Django 1.7 for a project. I h

Answer 1

I have solved it in a custom widget. I don't remember if I took parts from Django admin, or I have built from scratch.

So the form will be:

class OrderNewForm(forms.ModelForm):

   client = forms.ModelChoiceField(
       required=False,
       queryset=Client.objects.all(),
       widget=RelatedFieldWidgetCanAdd(Client, related_url="so_client_add")
                                )
   class Meta:
       model = Order
       fields = ('code', 'client')

And the widget, that renders the "+" button and link to the add popup in the admin interface or to a custom view you provice with the related_url argument is:

from django.core.urlresolvers import reverse
from django.utils.safestring import mark_safe
from django.forms import widgets
from django.conf import settings

class RelatedFieldWidgetCanAdd(widgets.Select):

    def __init__(self, related_model, related_url=None, *args, **kw):

        super(RelatedFieldWidgetCanAdd, self).__init__(*args, **kw)

        if not related_url:
            rel_to = related_model
            info = (rel_to._meta.app_label, rel_to._meta.object_name.lower())
            related_url = 'admin:%s_%s_add' % info

        # Be careful that here "reverse" is not allowed
        self.related_url = related_url

    def render(self, name, value, *args, **kwargs):
        self.related_url = reverse(self.related_url)
        output = [super(RelatedFieldWidgetCanAdd, self).render(name, value, *args, **kwargs)]
        output.append(u'<a href="%s" class="add-another" id="add_id_%s" onclick="return showAddAnotherPopup(this);"> ' % \
            (self.related_url, name))
        output.append(u'<img src="%sadmin/img/icon_addlink.gif" width="10" height="10" alt="%s"/></a>' % (settings.STATIC_URL, _('Add Another')))                                                                                                                               
       return mark_safe(u''.join(output))

Answer 2

for python3:

class RelatedFieldWidgetCanAdd(widgets.Select):

    def __init__(self, related_model, related_url=None, *args, **kw):

        super(RelatedFieldWidgetCanAdd, self).__init__(*args, **kw)

        if not related_url:
            rel_to = related_model
            info = (rel_to._meta.app_label, rel_to._meta.object_name.lower())
            related_url = 'admin:%s_%s_add' % info

        # Be careful that here "reverse" is not allowed
        self.related_url = related_url

    def render(self, name, value, *args, **kwargs):
        self.related_url = reverse(self.related_url)
        output = [super(RelatedFieldWidgetCanAdd, self).render(name, value, *args, **kwargs)]
        output.append('<a href="%s" class="add-another" id="add_id_%s" onclick="return showAddAnotherPopup(this);"> ' % \
            (self.related_url, name))
        output.append('<img src="%sadmin/img/icon_addlink.gif" width="10" height="10" alt="%s"/></a>' % (settings.STATIC_URL, 'Add Another'))
        return mark_safe(''.join(output))

Answer 3

And to add to the RelatedFieldWidgetCanAdd functionality to directly add new value to the field add "?_to_field=id&_popup=1" to the url... thus in python3 (thanks to Cyril):

class RelatedFieldWidgetCanAdd(widgets.Select):

def __init__(self, related_model, related_url=None, *args, **kw):

    super(RelatedFieldWidgetCanAdd, self).__init__(*args, **kw)

    if not related_url:
        rel_to = related_model
        info = (rel_to._meta.app_label, rel_to._meta.object_name.lower())
        related_url = 'admin:%s_%s_add' % info

    # Be careful that here "reverse" is not allowed
    self.related_url = related_url

def render(self, name, value, *args, **kwargs):
    self.related_url = reverse(self.related_url)
    output = [super(RelatedFieldWidgetCanAdd, self).render(name, value, *args, **kwargs)]
    output.append('<a href="%s?_to_field=id&_popup=1" class="add-another" id="add_id_%s" onclick="return showAddAnotherPopup(this);"> ' % \
        (self.related_url, name))
    output.append('<img src="%sadmin/img/icon_addlink.gif" width="10" height="10" alt="%s"/></a>' % (settings.STATIC_URL, 'Add Another'))
    return mark_safe(''.join(output))