Call functions out of jinja2 templates

2013-04-24 · 206 words · 1 minute read

I do a few webprojects with Flask and I love it! While creating a template i searched for a way to call functions from within the template, and found out that i can use a @app.context_processor decorator.

 1
 2
 3
 4
 5
 6
 7
 8
 9
10
11
12


@app.context_processor
def my_utility_processor():

    def date_now(format="%d.m.%Y %H:%M:%S"):
        """ returns the formated datetime """
        return datetime.datetime.now().strftime(format)

    def foo():
        """ returns bulshit """
        return "bar bar bar"

    return dict(date_now=date_now, baz=foo)

In the jinja2 template you can now simply call the functions like this:

1
2
3
4
5
6
7
8
9


{% raw %}

{% for n in news %}
    Give me some {{ baz() }}!
{% endfor %}

Copyright by me 2005 - {{ date_now("%Y") }}    

{% endraw %}

Lets assume news contains 2 elements, the result looks like this:

1
2
3
4
5


Give me some bar bar bar!

Give me some bar bar bar!

Copyright by me 2005 - 2013    

The important part is return dict(date_now=date_now, baz=foo). The first word is the key, the value is a function pointer. The key is the keyword you write in your template code {{ baz() }} for example, foo is the name of the function that get called.