Suppress "None" output as string in Jinja2

In new versions of Jinja2 (2.9+):

{{ value if value }}

In older versions of Jinja2 (prior to 2.9):

{{ value if value is not none }} works great.

if this raises an error about not having an else try using an else ..

{{ value if value is not none else '' }}


According to this post from the Pocco Mailing List: https://groups.google.com/d/msg/pocoo-libs/SQ9ubo_Kamw/TadIdab9eN8J

Armin Ronacher (creater of Jinja2/Flask, etc...) recommends the following "pythonic" snippet:

{{ variable or 0 }} {{ variable or '' }}

The notion here being that once again, explicit is preferable to implicit.

Edit: The selected answer is definitely the correct one. I haven't really come across a situation where a template variable would be either a string or the numeric zero, so the above snippets might help reduce the code noise in the template.


Another option is to use the finalize hook on the environment:

>>> import jinja2
>>> e = jinja2.Environment()
>>> e.from_string("{{ this }} / {{ that }}").render(this=0, that=None)
u'0 / None'

but:

>>> def my_finalize(thing):
...     return thing if thing is not None else ''
...
>>> e = jinja2.Environment(finalize=my_finalize)
>>> e.from_string("{{ this }} / {{ that }}").render(this=0, that=None)
u'0 / '

Default filter:

{{ value|default("", True) }}

Tags:

Python

Jinja2