Django’s bundled comments application is extremely useful on its own, but the amount of comment spam circulating on the Web today essentially makes it necessary to have some sort of automatic moderation system in place for any application which makes use of comments. To make this easier to handle in a consistent fashion, django.contrib.comments.moderation provides a generic, extensible comment-moderation system which can be applied to any model or set of models which want to make use of Django’s comment system.
The entire system is contained within django.contrib.comments.moderation, and uses a two-step process to enable moderation for any given model:
A simple example is the best illustration of this. Suppose we have the following model, which would represent entries in a Weblog:
from django.db import models
class Entry(models.Model):
title = models.CharField(maxlength=250)
body = models.TextField()
pub_date = models.DateField()
enable_comments = models.BooleanField()
Now, suppose that we want the following steps to be applied whenever a new comment is posted on an Entry:
Accomplishing this is fairly straightforward and requires very little code:
from django.contrib.comments.moderation import CommentModerator, moderator
class EntryModerator(CommentModerator):
email_notification = True
enable_field = 'enable_comments'
moderator.register(Entry, EntryModerator)
The CommentModerator class pre-defines a number of useful moderation options which subclasses can enable or disable as desired, and moderator knows how to work with them to determine whether to allow a comment, whether to moderate a comment which will be allowed to post, and whether to email notifications of new comments.
Most common comment-moderation needs can be handled by subclassing CommentModerator and changing the values of pre-defined attributes; the full range of built-in options is as follows.
If this is set to the name of a DateField or DateTimeField on the model for which comments are being moderated, new comments for objects of that model will be disallowed (immediately deleted) when a certain number of days have passed after the date specified in that field. Must be used in conjunction with close_after, which specifies the number of days past which comments should be disallowed. Default value is None.
Like auto_close_field, but instead of outright deleting new comments when the requisite number of days have elapsed, it will simply set the is_public field of new comments to False before saving them. Must be used in conjunction with moderate_after, which specifies the number of days past which comments should be moderated. Default value is None.
If auto_close_field is used, this must specify the number of days past the value of the field specified by auto_close_field after which new comments for an object should be disallowed. Allowed values are None, 0 (which disallows comments immediately), or any positive integer. Default value is None.
If True, any new comment on an object of this model which survives moderation (i.e., is not deleted) will generate an email to site staff. Default value is False.
If this is set to the name of a BooleanField on the model for which comments are being moderated, new comments on objects of that model will be disallowed (immediately deleted) whenever the value of that field is False on the object the comment would be attached to. Default value is None.
If auto_moderate_field is used, this must specify the number of days past the value of the field specified by auto_moderate_field after which new comments for an object should be marked non-public. Allowed values are None, 0 (which moderates comments immediately), or any positive integer. Default value is None.
Simply subclassing CommentModerator and changing the values of these options will automatically enable the various moderation methods for any models registered using the subclass.
For situations where the built-in options listed above are not sufficient, subclasses of CommentModerator can also override the methods which actually perform the moderation, and apply any logic they desire. CommentModerator defines three methods which determine how moderation will take place; each method will be called by the moderation system and passed two arguments: comment, which is the new comment being posted, content_object, which is the object the comment will be attached to, and request, which is the HttpRequest in which the comment is being submitted:
Should return True if the comment should be allowed to post on the content object, and False otherwise (in which case the comment will be immediately deleted).
If email notification of the new comment should be sent to site staff or moderators, this method is responsible for sending the email.
Should return True if the comment should be moderated (in which case its is_public field will be set to False before saving), and False otherwise (in which case the is_public field will not be changed).
The moderation system, represented by django.contrib.comments.moderation.moderator is an instance of the class Moderator, which allows registration and “unregistration” of models via two methods:
Takes two arguments: the first should be either a model class or list of model classes, and the second should be a subclass of CommentModerator, and register the model or models to be moderated using the options defined in the CommentModerator subclass. If any of the models are already registered for moderation, the exception AlreadyModerated will be raised.
Takes one argument: a model class or list of model classes, and removes the model or models from the set of models which are being moderated. If any of the models are not currently being moderated, the exception NotModerated will be raised.
Most use cases will work easily with simple subclassing of CommentModerator and registration with the provided Moderator instance, but customization of global moderation behavior can be achieved by subclassing Moderator and instead registering models with an instance of the subclass.
In addition to the Moderator.register() and Moderator.unregister() methods detailed above, the following methods on Moderator can be overridden to achieve customized behavior:
Determines how moderation is set up globally. The base implementation in Moderator does this by attaching listeners to the comment_will_be_posted and comment_was_posted signals from the comment models.
In the base implementation, applies all pre-save moderation steps (such as determining whether the comment needs to be deleted, or whether it needs to be marked as non-public or generate an email).
In the base implementation, applies all post-save moderation steps (currently this consists entirely of deleting comments which were disallowed).
Dec 23, 2012