Bleach is an HTML sanitizing library that escapes or strips markup and
attributes based on a white list. Bleach can also linkify text safely, applying
filters that Django's
urlize filter cannot, and optionally setting
attributes, even on links already in the text.
Bleach is intended for sanitizing text from untrusted sources. If you find yourself jumping through hoops to allow your site administrators to do lots of things, you're probably outside the use cases. Either trust those users, or don't.
Because it relies on html5lib, Bleach is as good as modern browsers at dealing with weird, quirky HTML fragments. And any of Bleach's methods will fix unbalanced or mis-nested tags.
The version on github is the most up-to-date and contains the latest bug fixes.
The simplest way to use Bleach is:
>>> import bleach >>> bleach.clean('an <script>evil()</script> example') u'an <script>evil()</script> example' >>> bleach.linkify('an http://example.com url') u'an <a href="http://example.com" rel="nofollow">http://example.com</a> url >>> bleach.delinkify('a <a href="http://ex.mp">link</a>') u'a link'
NB: Bleach always returns a
unicode object, whether you give it a
bytestring or a
unicode object, but Bleach does not attempt to detect
incoming character encodings, and will assume UTF-8. If you are using a
different character encoding, you should convert from a bytestring to
unicode before passing the text to Bleach.
delinkify() can take several optional
keyword arguments to customize their behavior.
bleach.clean() is the primary tool in Bleach. It uses html5lib to parse a
document fragment into a tree and does the sanitization during tokenizing,
which is incredibly powerful and has several advantages over regular
- A whitelist of HTML tags. Must be a list. Defaults to
- A whitelist of HTML attributes. Either a list, in which case all attributes
are allowed on all elements, or a dict, with tag names as keys and lists of
allowed attributes as values ('*' is a wildcard key to allow an attribute on
any tag). Or it is possible to pass a callable instead of a list that accepts
name and value of attribute and returns True of False. Defaults to
- A whitelist of allowed CSS properties within a
styleattribute. (Note that
styleattributes are not allowed by default.) Must be a list. Defaults to
- Strip disallowed HTML instead of escaping it. A boolean. Defaults to
- Strip HTML comments. A boolean. Defaults to
bleach.linkify() turns things that look like URLs or (optionally) email
addresses and turns them into links. It does this smartly, only looking in text
nodes, and never within
There are options that affect output, and some of these are also applied to
links already found in the text. These are designed to allow you to set
target, or push outgoing links
through a redirection URL, and do this to links already in the text, as well.
rel="nofollow"to non-relative links (both created by
linkify()and those already present in the text). Defaults to
- A callable through which the
hrefattribute of links (both created by
linkify()and already present in the text) will be passed. Must accept a single argument and return a string.
- A callable through which the text of links (only those created by
linkify) will be passed. Must accept a single argument and return a string.
- Do not create new links inside
<pre>sections. Still follows
nofollow. Defaults to
- Linkify email addresses with
mailto:. Defaults to
- Set a
targetattribute on links. Like
None, will set the attribute on links already in the text, as well. Defaults to
bleach.delinkify() is basically the opposite of
linkify(). It strips
links out of text except, optionally, relative links, or links to domains
- Allow links to the domains in this list. Set to
Noneor an empty list to disallow all non-relative domains. See below for wildcards. Defaults to
- Allow relative links (i.e. those with no hostname). Defaults to
To allow links to a domain and its subdomains,
allow_domains accepts two
types of wildcard arguments in domains:
Allow a single level of subdomain. This can be anywhere in the hostname, even the TLD. This allows you to, for example, allow links to
*.example.comwill match both
>>> delinkify('<a href="http://foo.ex.mp">bar</a>', \ ... allow_domains=['*.ex.*']) u'<a href="http://foo.ex.mp">bar</a>' >>> delinkify('<a href="http://ex.mp">bar</a>', allow_domains=['*.ex.mp']) u'<a href="http://ex.mp">bar</a>
To allow any number of preceding subdomains, you can start a hostname with
**. Note that unlike
**may only appear once, and only at the beginning of a hostname.
>>> delinkify('<a href="http://a.b.ex.mp">t</a>', \ ... allow_domains=['**.ex.mp']) u'<a href="http://a.b.ex.mp">t</a>'
**appears anywhere but the beginning of a hostname,
bleach.ValidationError(which is a
ValueErrorsubclass, for easy catching).