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Jinja, also commonly referred to as "Jinja2" to specify the newest release version, is a Python template engine used to create HTML, XML or other markup formats that are returned to the user via an HTTP response.
Jinja2 being a templating language has no need for wide choice of loop types so we only get for loop. For loops start with {% for my_item in my_collection %} and end with {% endfor %} . This is very similar to how you'd loop over an iterable in Python.
There are two ways to do it. The direct approach would be to simply call (and print) the strftime() method in your template, for example
{{ car.date_of_manufacture.strftime('%Y-%m-%d') }}
Another, sightly better approach would be to define your own filter, e.g.:
from flask import Flask
import babel
app = Flask(__name__)
@app.template_filter()
def format_datetime(value, format='medium'):
if format == 'full':
format="EEEE, d. MMMM y 'at' HH:mm"
elif format == 'medium':
format="EE dd.MM.y HH:mm"
return babel.dates.format_datetime(value, format)
(This filter is based on babel for reasons regarding i18n, but you can use strftime too). The advantage of the filter is, that you can write
{{ car.date_of_manufacture|format_datetime }}
{{ car.date_of_manufacture|format_datetime('full') }}
which looks nicer and is more maintainable. Another common filter is also the "timedelta" filter, which evaluates to something like "written 8 minutes ago". You can use babel.dates.format_timedelta for that, and register it as filter similar to the datetime example given here.
Here's the filter that I ended up using for strftime in Jinja2 and Flask
@app.template_filter('strftime')
def _jinja2_filter_datetime(date, fmt=None):
date = dateutil.parser.parse(date)
native = date.replace(tzinfo=None)
format='%b %d, %Y'
return native.strftime(format)
And then you use the filter like so:
{{car.date_of_manufacture|strftime}}
I think you have to write your own filter for that. It's actually the example for custom filters in the documentation: http://jinja.pocoo.org/docs/api/#custom-filters
If you are dealing with a lower level time object (I often just use integers), and don't want to write a custom filter for whatever reason, an approach I use is to pass the strftime function into the template as a variable, where it can be called where you need it.
For example:
import time
context={
'now':int(time.time()),
'strftime':time.strftime } # Note there are no brackets () after strftime
# This means we are passing in a function,
# not the result of a function.
self.response.write(jinja2.render_template('sometemplate.html', **context))
Which can then be used within sometemplate.html:
<html>
<body>
<p>The time is {{ strftime('%H:%M%:%S',now) }}, and 5 seconds ago it was {{ strftime('%H:%M%:%S',now-5) }}.
</body>
</html>
You can use it like this in template without any filters
{{ car.date_of_manufacture.strftime('%Y-%m-%d') }}
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