That file format is called Property List because they often store application properties such as user settings.

This blog post introductes a Django application for serializing Django model objects and regular Python types into Property List XML!

The package is called django-plist and the source is available at Github. It is also available from the Python Package Index, install it with easy_install django_plist.

The README file documents the installation process and how to use the application to serialize Django objects, but I’ll give a small teaser here, just to get your attention!

Say we have a model Blog and we want to expose all Blog objects as an array of objects at one URL endpoint and single Blog objects as a dictionary at another endpoint. Point your Objective-C code to the URLs and read it with [NSArray arrayWithContentsOfUrl] and [NSDictionary dictionaryWithContentsOfUrl]. And voilá your Python objects are available as arrays and dictionaries in Objective-C!

The main interface for django-plist is two generic views, you’ll use these views just as you would use the generic views in Django:

from django_plist.views.generic import plist_array, plist_dict

blog_info = {'queryset': Blog.objects.all()}

urlpatterns = patterns('',
    url('^all_entries/$', plist_array, blog_info),
    url('^single_entry/(?P<object_id>\d+)/$', plist_dict, blog_info),
)

Read about the different ways you can customize the generic views and the parameters they take in the documentation.

If you find django-plist useful, please drop me a line!

The long story in a short sentence is that you cannot subclass or customize CommentForm in todays version without getting your hands dirty.

I recently enabled Captcha verification to comments on this site to prevent spammers from filling my database with non-public comments. Tor Brede Vekterli has written about how to do this by using signals, but for technical reasons I’d rather not go down that road. So I landed on the next possible strategy, namely subclassing CommentForm.

My subclass is a standard Django form:

class CaptchaCommentForm(CommentForm):
    captcha = forms.CharField(max_length=20, label='Enter this word')

    def clean_captcha(self):
        # verify self.cleaned_data['captcha'] here, details omitted,
        # raise forms.ValidationError if verification fails

Since I wanted to control the way this field is displayed by adding an image I also edited my form template. In my comments/form.html template I added a check to include the captcha image:

{% for field in form %}
    {% ifequal field.name "captcha" %}
        do whatever it takes to display the custom field.
    {% else %}
        display regular comment form field
    {% endifequal %}
{% endfor %}

As I mentioned above the comments framework is not really designed to be extended or customized in this way. To make the framework use my CaptchaCommentForm instead of its own CommentForm I resorted to monkeypatching!

The framework uses a single function, comments.get_form, whenever it needs a fresh CommentForm instance. What I wanted is for that function to return my CaptchaCommentForm instead. Here is what I did to my urls.py:

from django.contrib import comments
from forms import CaptchaCommentForm

def override_get_form():
    return CaptchaCommentForm()
comments.get_form = override_get_form

Thanks to the dynamic features of Python we can simply replace the original function with our own that returns the correct instance. Not pretty, but it works.

The proper way to do this is of course to use the ModelAdmin classes that were introduced with the merge of the newforms-admin branch.

Declare your model as usual in models.py without the inner Admin class:

class Article(models.Model):
    title = models.CharField()
    slug = models.SlugField()

Then declare the ModelAdmin class in admins.py. This is where you set properties regarding the admin interface, it replaces the old-style inner Admin class:

class ArticleAdmin(admin.ModelAdmin):
    prepopulated_fields = {"slug": ("title",)}
admin.site.register(Article, ArticleAdmin)

This is the correct way to do it. Rip out the inner Admin-classes and create new ModelAdmin-classes. Read the new and updated documentation for more on newforms-admin.