jonashaag · September 7, 2011 09:41 · Sep 7, 2011 · Sep 7, 2011 · Sep 7, 2011 · Sep 7, 2011
diff --git a/3-admin.py b/3-admin.py
@@ -7,4 +7,4 @@ def categories(instance):
 class PostAdmin(ModelAdmin):
     list_display = ['title', categories]
 
-site.register(Post, PostAdmin)
+site.register(Post, PostAdmin)
diff --git a/0howto-listfield-django-admin.rst → 0-howto-listfield-django-admin.rst b/0howto-listfield-django-admin.rst → 0-howto-listfield-django-admin.rst
diff --git a/models.py → 1-models.py b/models.py → 1-models.py
diff --git a/forms.py → 2-forms.py b/forms.py → 2-forms.py
diff --git a/admin.py → 3-admin.py b/admin.py → 3-admin.py
diff --git a/howto-listfield-django-admin.rst → 0howto-listfield-django-admin.rst b/howto-listfield-django-admin.rst → 0howto-listfield-django-admin.rst
diff --git a/admin.py b/admin.py
@@ -0,0 +1,10 @@
+from django.contrib.admin import site, ModelAdmin
+from models import Post
+
+def categories(instance):
+    return ', '.join(instance.categories)
+
+class PostAdmin(ModelAdmin):
+    list_display = ['title', categories]
+
+site.register(Post, PostAdmin)
diff --git a/forms.py b/forms.py
@@ -0,0 +1,10 @@
+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(',')]
diff --git a/models.py b/models.py
@@ -0,0 +1,11 @@
+from django.db import models
+from djangotoolbox.fields import ListField
+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()
diff --git a/howto-listfield-django-admin.rst b/howto-listfield-django-admin.rst
@@ -35,7 +35,7 @@ Trying to edit some posts in the admin crashes with::
 Solution
 --------
 What we need to do is to teach the admin how to display a ``ListField`` in the
-edit view. Our form field will a simple ``<input type=text>`` input box with
+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 <https://docs.djangoproject.com/en/dev/ref/forms/fields/#creating-custom-fields>`_
 and your favourite search engine using the terms "Django custom form field".

diff --git a/howto-listfield-django-admin.rst b/howto-listfield-django-admin.rst
@@ -71,7 +71,7 @@ string which is then displayed in the input box.
 
 Let's add a post and check out the resulting model object in the database:
 
-.. image:: edit-form.png
+.. image:: http://img30.imageshack.us/img30/2391/editform.png
 
 ::
 

diff --git a/howto-listfield-django-admin.rst b/howto-listfield-django-admin.rst
@@ -0,0 +1,81 @@
+Howto use ListFields in Django's admin
+======================================
+
+Problem
+-------
+Consider this blog post model:
+
+``models.py``
+.............
+::
+
+   from django.db import models
+   from djangotoolbox.fields import ListField
+
+   class Post(models.Model):
+       title = models.CharField(max_length=100)
+       categories = ListField()
+
+
+``admin.py``
+............
+::
+
+   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'>
+
+
+Solution
+--------
+What we need to do is to teach the admin how to display a ``ListField`` in the
+edit view. Our form field will a simple ``<input type=text>`` input box with
+comma-separated category names. For more about custom form fields, refer to the
+`Django documentation <https://docs.djangoproject.com/en/dev/ref/forms/fields/#creating-custom-fields>`_
+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:
+
+.. image:: edit-form.png
+
+::
+
+   >>> Post.objects.get(title='foo').categories
+   [u'spam', u'eggs', u'bar']
+
+It worked! Simple, isn't it?