Allowing tags with Google App Engine and Jinja2

Question

In my web app, the user can make blog posts. When I display the blog post, newlines aren\'t shown because I didn\'t replace the new lines with
tags.

Answer 1

You can create a jinja2 filter:

import re
from jinja2 import evalcontextfilter, Markup, escape

_paragraph_re = re.compile(r'(?:\r\n|\r|\n){2,}')

@evalcontextfilter
def nl2br(eval_ctx, value):
    result = u'\n\n'.join(u'
%s
' % p.replace('\n', '
\n')
                          for p in _paragraph_re.split(escape(value)))
    if eval_ctx.autoescape:
        result = Markup(result)
    return result

You need to add the filter to your jinja2 Environment before you can use it:

JINJA2_ENV.filters['nl2br'] = jinja2_filters.nl2br

In your template you can use that filter:

{{post.content|nl2br}}