Tying in to Django Admin’s Model History

djangodjango-admindjango-models

The Setup:

I'm working on a Django application which allows users to create an object in the database and then go back and edit it as much as they desire.
Django's admin site keeps a history of the changes made to objects through the admin site.

The Question:

How do I hook my application in to the admin site's change history so that I can see the history of changes users make to their "content"?

Best Answer

The admin history is just an app like any other Django app, with the exception being special placement on the admin site.

The model is in django.contrib.admin.models.LogEntry.

When a user makes a change, add to the log like this (stolen shamelessly from contrib/admin/options.py:

from django.utils.encoding import force_unicode
from django.contrib.contenttypes.models import ContentType
from django.contrib.admin.models import LogEntry, ADDITION
LogEntry.objects.log_action(
    user_id         = request.user.pk, 
    content_type_id = ContentType.objects.get_for_model(object).pk,
    object_id       = object.pk,
    object_repr     = force_unicode(object), 
    action_flag     = ADDITION
)

where object is the object that was changed of course.

Now I see Daniel's answer and agree with him, it is pretty limited.

In my opinion a stronger approach is to use the code from Marty Alchin in his book Pro Django (see Keeping Historical Records starting at page 263). There is an application django-simple-history which implements and extends this approach (docs here).

Related Solutions

Extending the User model with custom fields in Django

The least painful and indeed Django-recommended way of doing this is through a OneToOneField(User) property.

Extending the existing User model

…

If you wish to store information related to User, you can use a one-to-one relationship to a model containing the fields for additional information. This one-to-one model is often called a profile model, as it might store non-auth related information about a site user.

That said, extending django.contrib.auth.models.User and supplanting it also works...

Substituting a custom User model

Some kinds of projects may have authentication requirements for which Django’s built-in User model is not always appropriate. For instance, on some sites it makes more sense to use an email address as your identification token instead of a username.

[Ed: Two warnings and a notification follow, mentioning that this is pretty drastic.]

I would definitely stay away from changing the actual User class in your Django source tree and/or copying and altering the auth module.

Python – a “slug” in Django

A "slug" is a way of generating a valid URL, generally using data already obtained. For instance, a slug uses the title of an article to generate a URL. I advise to generate the slug by means of a function, given the title (or another piece of data), rather than setting it manually.

An example:

<title> The 46 Year Old Virgin </title>
<content> A silly comedy movie </content>
<slug> the-46-year-old-virgin </slug>

Now let's pretend that we have a Django model such as:

class Article(models.Model):
    title = models.CharField(max_length=100)
    content = models.TextField(max_length=1000)
    slug = models.SlugField(max_length=40)

How would you reference this object with a URL and with a meaningful name? You could for instance use Article.id so the URL would look like this:

www.example.com/article/23

Or, you might want to reference the title like this:

www.example.com/article/The 46 Year Old Virgin

Since spaces aren't valid in URLs, they must be replaced by %20, which results in:

www.example.com/article/The%2046%20Year%20Old%20Virgin

Both attempts are not resulting in very meaningful, easy-to-read URL. This is better:

www.example.com/article/the-46-year-old-virgin

In this example, the-46-year-old-virgin is a slug: it is created from the title by down-casing all letters, and replacing spaces by hyphens -.

Also see the URL of this very web page for another example.

Best Answer

Related Solutions

Extending the User model with custom fields in Django

Extending the existing User model

Substituting a custom User model

Python – a “slug” in Django

Related Topic