premailer
=========
|Travis|
|Coverage Status|
Looking for sponsors
--------------------
This project is actively looking for corporate sponsorship. If you want
to help making this an active project consider `pinging
Peter <http://www.peterbe.com/contact>`__ and we can talk about putting
up logos and links to your company.
Python versions
---------------
Our
`tox.ini <https://github.com/peterbe/premailer/blob/master/tox.ini>`__
makes sure premailer works in:
- Python 2.6
- Python 2.7
- Python 3.3
- Python 3.4
- Python 3.5
- PyPy
Turns CSS blocks into style attributes
--------------------------------------
When you send HTML emails you can't use style tags but instead you have
to put inline ``style`` attributes on every element. So from this:
.. code:: html
<html>
<style type="text/css">
h1 { border:1px solid black }
p { color:red;}
</style>
<h1 style="font-weight:bolder">Peter</h1>
<p>Hej</p>
</html>
You want this:
.. code:: html
<html>
<h1 style="font-weight:bolder; border:1px solid black">Peter</h1>
<p style="color:red">Hej</p>
</html>
premailer does this. It parses an HTML page, looks up ``style`` blocks
and parses the CSS. It then uses the ``lxml.html`` parser to modify the
DOM tree of the page accordingly.
Getting started
---------------
If you haven't already done so, install ``premailer`` first:
::
$ pip install premailer
Next, the most basic use is to use the shortcut function, like this:
::
>>> from premailer import transform
>>> print transform("""
... <html>
... <style type="text/css">
... h1 { border:1px solid black }
... p { color:red;}
... p::first-letter { float:left; }
... </style>
... <h1 style="font-weight:bolder">Peter</h1>
... <p>Hej</p>
... </html>
... """)
<html>
<head></head>
<body>
<h1 style="font-weight:bolder; border:1px solid black">Peter</h1>
<p style="color:red">Hej</p>
</body>
</html>
For more advanced options, check out the code of the ``Premailer`` class
and all its options in its constructor.
You can also use premailer from the command line by using his main
module.
::
$ python -m premailer -h
usage: python -m premailer [options]
optional arguments:
-h, --help show this help message and exit
-f [INFILE], --file [INFILE]
Specifies the input file. The default is stdin.
-o [OUTFILE], --output [OUTFILE]
Specifies the output file. The default is stdout.
--base-url BASE_URL
--remove-internal-links PRESERVE_INTERNAL_LINKS
Remove links that start with a '#' like anchors.
--exclude-pseudoclasses
Pseudo classes like p:last-child', p:first-child, etc
--preserve-style-tags
Do not delete <style></style> tags from the html
document.
--remove-star-selectors
All wildcard selectors like '* {color: black}' will be
removed.
--remove-classes Remove all class attributes from all elements
--strip-important Remove '!important' for all css declarations.
--method METHOD The type of html to output. 'html' for HTML, 'xml' for
XHTML.
--base-path BASE_PATH
The base path for all external stylsheets.
--external-style EXTERNAL_STYLES
The path to an external stylesheet to be loaded.
--disable-basic-attributes DISABLE_BASIC_ATTRIBUTES
Disable provided basic attributes (comma separated)
--disable-validation Disable CSSParser validation of attributes and values
--pretty Pretty-print the outputted HTML.
A basic example:
::
$ python -m premailer --base-url=http://google.com/ -f newsletter.html
<html>
<head><style>.heading { color:red; }</style></head>
<body><h1 class="heading" style="color:red"><a href="http://google.com/">Title</a></h1></body>
</html>
The command line interface supports standard input.
::
$ echo '<style>.heading { color:red; }</style><h1 class="heading"><a href="/">Title</a></h1>' | python -m premailer --base-url=http://google.com/
<html>
<head><style>.heading { color:red; }</style></head>
<body><h1 class="heading" style="color:red"><a href="http://google.com/">Title</a></h1></body>
</html>
Turning relative URLs into absolute URLs
----------------------------------------
Another thing premailer can do for you is to turn relative URLs (e.g.
"/some/page.html" into "http://www.peterbe.com/some/page.html"). It does
this to all ``href`` and ``src`` attributes that don't have a ``://``
part in it. For example, turning this:
.. code:: html
<html>
<body>
<a href="/">Home</a>
<a href="page.html">Page</a>
<a href="http://crosstips.org">External</a>
<img src="/folder/">Folder</a>
</body>
</html>
Into this:
.. code:: html
<html>
<body>
<a href="http://www.peterbe.com/">Home</a>
<a href="http://www.peterbe.com/page.html">Page</a>
<a href="http://crosstips.org">External</a>
<img src="http://www.peterbe.com/folder/">Folder</a>
</body>
</html>
by using ``transform('...', base_url='http://www.peterbe.com/')``.
Ignore certain ``<style>`` or ``<link>`` tags
---------------------------------------------
Suppose you have a style tag that you don't want to have processed and
transformed you can simply set a data attribute on the tag like:
.. code:: html
<head>
<style>/* this gets processed */</style>
<style data-premailer="ignore">/* this gets ignored */</style>
</head>
That tag gets completely ignored except when the HTML is processed, the
attribute ``data-premailer`` is removed.
It works equally for a ``<link>`` tag like:
.. code:: html
<head>
<link rel="stylesheet" href="foo.css" data-premailer="ignore">
</head>
HTML attributes created additionally
------------------------------------
Certain HTML attributes are also created on the HTML if the CSS contains
any ones that are easily translated into HTML attributes. For example,
if you have this CSS: ``td { background-color:#eee; }`` then this is
transformed into ``style="background-color:#eee"`` AND as an HTML
attribute ``bgcolor="#eee"``.
Having these extra attributes basically as a "back up" for really shit
email clients that can't even take the style attributes. A lot of
professional HTML newsletters such as Amazon's use this. You can disable
some attributes in ``disable_basic_attributes``.
Capturing logging from ``cssutils``
-----------------------------------
`cssutils <https://pypi.python.org/pypi/cssutils/>`__ is the library that
``premailer`` uses to parse CSS. It will use the python ``logging`` module
to mention all issues it has with parsing your CSS. If you want to capture
this, you have to pass in ``cssutils_logging_handler`` and
``cssutils_logging_level`` (optional). For example like this:
.. code:: python
>>> import logging
>>> import premailer
>>> from io import StringIO
>>> mylog = StringIO()
>>> myhandler = logging.StreamHandler(mylog)
>>> p = premailer.Premailer("""
... <html>
... <style type="text/css">
... @keyframes foo { from { opacity: 0; } to { opacity: 1; } }
... </style>
... <p>Hej</p>
... </html>
... """,
... cssutils_logging_handler=myhandler,
... cssutils_logging_level=logging.INFO)
>>> result = p.transform()
>>> mylog.getvalue()
'CSSStylesheet: Unknown @rule found. [2:1: @keyframes]\n'
Running tests with tox
----------------------
To run ``tox`` you don't need to have all available Python versions
installed because it will only work on those you have. To use ``tox``
first install it:
::
pip install tox
Then simply start it with:
::
tox
Donations aka. the tip jar
--------------------------
If you enjoy, benefit and want premailer to continue to be an actively
maintained project please consider supporting me on
`Gratipay <https://gratipay.com/peterbe/>`__.
|Gratipay|
.. |Travis| image:: https://travis-ci.org/peterbe/premailer.png?branch=master
:target: https://travis-ci.org/peterbe/premailer
.. |Coverage Status| image:: https://coveralls.io/repos/peterbe/premailer/badge.svg?branch=master&service=github
:target: https://coveralls.io/github/peterbe/premailer?branch=master
.. |Gratipay| image:: https://img.shields.io/gratipay/peterbe.svg
:target: https://gratipay.com/peterbe/
Frédéric Péters
9952ed6711