How to update timestamp as a global variable in Jinja2?

Question

I know that there were similar questions here, but they didn't help me.

In the main py file I just set the global variable named nowts as follows:

app.jinja_env.globals['nowts'] = datetime.datetime.now()

And in the main (base) template (base.html file) I just pass and formatting datetime as follows:

{% block navbar %}
... 
<p>{{ nowts.strftime('%A, %b %d %Y / %X') }}</p>
...
{% endblock %}

For example, output is:

Wednesday, Mar 26 2014 / 11:57:51

As you see date and time are displayed correctly, but only once. After a few minutes I re-open the main page (or subpages) and the time is still the same. How to update the nowts global variable always if the user refreshes the page?

Answer 1

Use a context processor to inject values per request:

@app.context_processor
def inject_template_globals():
    return {
        'nowts': datetime.datetime.utcnow(),
    }

You generally want to use UTC time, not local time, for web servers. You never know where in the world your request comes from.