Consider this blog post model:
from django.db import models
from djangotoolbox.fields import ListField
class Post(models.Model):
title = models.CharField(max_length=100)
categories = ListField()
from django.contrib.admin import site from models import Post site.register(Post)
Trying to edit some posts in the admin crashes with:
No form field implemented for <class 'djangotoolbox.fields.ListField'>
What we need to do is to teach the admin how to display a ListField in the
edit view. Our form field will be a simple <input type=text> input box with
comma-separated category names. For more about custom form fields, refer to the
Django documentation
and your favourite search engine using the terms "Django custom form field".
First, we need to subclass ListField to override the formfield method:
from .forms import StringListField
class CategoryField(ListField):
def formfield(self, **kwargs):
return models.Field.formfield(self, StringListField, **kwargs)
class Post(models.Model):
title = models.CharField(max_length=100)
categories = CategoryField()
Then, in forms.py, we define StringListField:
from django import forms
class StringListField(forms.CharField):
def prepare_value(self, value):
return ', '.join(value)
def to_python(self, value):
if not value:
return []
return [item.strip() for item in value.split(',')]
This will covert the comma-separated input box contents into a Python list,
and the list value that is fetched from the database int a comma-separated
string which is then displayed in the input box.
Let's add a post and check out the resulting model object in the database:
>>> Post.objects.get(title='foo').categories [u'spam', u'eggs', u'bar']
It worked! Simple, isn't it?
Thanks. How would you model finding a post by one of the tags?