Bleach is a Python module that takes any HTML input, and returns valid, sanitised HTML that contains only an allowed subset of HTML tags, attributes and styles. django-bleach
is a Django app that makes using bleach
extremely easy.
Install
django-bleach
viapip
:pip install django-bleach
Add
django-bleach
to yourINSTALLED_APPS
:INSTALLED_APPS = [ # ... 'django_bleach', # ... ]
Select some sensible defaults for the allowed tags, attributes and styles; and the behaviour when unknown tags are encountered. Each of these are optional, and default to using the
bleach
defaults. See the bleach documentation:# Which HTML tags are allowed BLEACH_ALLOWED_TAGS = ['p', 'b', 'i', 'u', 'em', 'strong', 'a'] # Which HTML attributes are allowed BLEACH_ALLOWED_ATTRIBUTES = ['href', 'title', 'style'] # Which CSS properties are allowed in 'style' attributes (assuming # style is an allowed attribute) BLEACH_ALLOWED_STYLES = [ 'font-family', 'font-weight', 'text-decoration', 'font-variant'] # Strip unknown tags if True, replace with HTML escaped characters if # False BLEACH_STRIP_TAGS = True # Strip comments, or leave them in. BLEACH_STRIP_COMMENTS = False
Select the default widget for bleach fields. This defaults to
django.forms.Textarea
, but you will probably want to replace it with a WYSIWYG editor, or something similar:# Use the CKEditorWidget for bleached HTML fields BLEACH_DEFAULT_WIDGET = 'wysiwyg.widgets.WysiwygWidget'
I use django-ckeditor in my projects, but what you use is up to you.
django-bleach
provides three ways of creating bleached output. The simplest way of including user-editable HTML content that is automatically sanitised is by using the BleachField
model field:
# in app/models.py
from django import models
from django_bleach.models import BleachField
class Post(models.Model):
title = models.CharField()
content = BleachField()
# ...
BleachField
takes the following arguments, to customise the output of bleach
. See the bleach documentation for their use:
allowed_tags
allowed_attributes
allowed_styles
strip_tags
strip_comments
In addition to the bleach
-specific arguments, the BleachField
model field accepts all of the normal field attributes. Behind the scenes, it is a TextField
, and accepts all the same arguments as the default TextField
does.
The BleachField
model field makes use of the BleachField
form field to do all of the work. It provides no sanitisation facilities itself. This is considered a bug, but a clean solution has not yet been implemented. Any pull requests fixing this will be gratefully applied. As long as the BleachField
model field is only used with BleachField
form fields, there will be no problem. If this is not the case, sanitised HTML can not be guaranteed.
A BleachField
form field is provided. This field sanitises HTML input from the user, and presents safe, clean HTML to your Django application. This is where most of the work is done.
If you have a piece of content from somewhere that needs to be printed in a template, you can use the bleach
filter:
{% load bleach_tags %}
{{ some_unsafe_content|bleach }}
If filter has no arguments it uses default settings defined in your application settings. You can override allowed tags by specifying them as a parameter to the filter:
{{ some_unsafe_content|bleach:"p,span" }}
There is also bleach_linkify
which uses the linkify function of bleach which converts URL-like strings in an HTML fragment to links
This function converts strings that look like URLs, domain names and email addresses in text that may be an HTML fragment to links, while preserving:
- links already in the string
- urls found in attributes
- email addresses