#4467: handle a huge list of ForeignKey objects by implementing a
CategorizedModelChoiceField
-----------------------+----------------------------------------------------
Reporter: ulda | Owner: adrian
Status: new | Component: django.newforms
Version: SVN | Keywords: ForeignKey ModelChoiceField
Stage: Unreviewed | Has_patch: 0
-----------------------+----------------------------------------------------
Think of having a model like this:
{{{
PRKAT_CHOICES= (
('M','Metrisch'),
('MF', 'Metrisch-Fein'),
# some more here left out for shortness...
)
class Profil(models.Model):
kategorie=models.CharField('Kategorie',maxlength=4,choices=PRKAT_CHOICES)
bezeichnung=models.CharField('Bezeichnung',maxlength=30)
}}}
and your database fills up with profile objects in hundreds with different
categories.
Now another model is calling this model like
{{{
class Karte(models.Model):
ba_nr=models.PositiveIntegerField("BA-Nr",primary_key=True)
datum=models.DateField("Datum",default=date.today)
profil=ForeignKey(Profil)
}}}
and in your forms for Karte you get an ugly select filling the screen.
Attached you find a CategorizedModelChoiceField. With this in hand, you
subclass ForeignKey to your model specific ProfileKey
{{{
class ProfilKey(models.ForeignKey):
def formfield(self,**kwargs):
defaults = {'form_class': CategorizedModelChoiceField, 'queryset':
self.rel.to._default_manager.all(), 'category': 'kategorie' ,
'callback_link': '/pr/list_of_profiles_for_category/'}
defaults.update(kwargs)
return super(ProfilKey, self).formfield(**defaults)
}}}
and change the ForeignKey definition in your other model to
{{{
profil=ProfileKey(Profil)
}}}
Because the whole thing works with a simple kind of ajax, you need a
callback function in your urls like this:
{{{
urlpatterns = patterns('myproject.categorizedmodelchoicefield',
(r'^pr/list_of_profiles_for_category/$','get_choices_for_category',
{ 'queryset': Profil.objects.all(),
'category_name':'kategorie' } ),
)
}}}
and voilais: in your forms for Karte you get two selects for category and
the actual choice value which updates according to the users selection.
you may also use the formfield_callback but why not using the objects if
they are handy...
making it work you need:
* CategorizedModelChoiceField.py attached
* JsonResponse from djangosnipplets.org
* http.Request form openjsan.org loaded somewhere in your base templates
I think something like this should be included as example extension to
newforms and to using django/json/ajax. therefore i didn't post ant
djangosnipplets.
the javascript code maybe looks ugly, but this is because it was the first
time i did javascript.
--
Ticket URL: <http://code.djangoproject.com/ticket/4467>
Django Code <http://code.djangoproject.com/>
The web framework for perfectionists with deadlines
--~--~---------~--~----~------------~-------~--~----~
You received this message because you are subscribed to the Google Groups
"Django updates" group.
To post to this group, send email to [email protected]
To unsubscribe from this group, send email to [EMAIL PROTECTED]
For more options, visit this group at
http://groups.google.com/group/django-updates?hl=en
-~----------~----~----~----~------~----~------~--~---
