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) }}