How to Render Human Readable Time in Jinja?

From a UX perspective, human-readable (or humanized) time is a must-have. “5 hours ago,” instead of “22th Dec, 2018 09:18:18 AM” is so much easier to parse. To render timestamps in that format inside a Jinja template, we can create a filter in the flask application code.

{% raw  %}def humanize_ts(timestamp=False):
    """
    Get a datetime object or a int() Epoch timestamp and return a
    pretty string like 'an hour ago', 'Yesterday', '3 months ago',
    'just now', etc
    """
    now = datetime.now()
    diff = now - datetime.fromtimestamp(time)
    second_diff = diff.seconds
    day_diff = diff.days

    if day_diff < 0:
        return ''

    if day_diff == 0:
        if second_diff < 10:
            return "just now"
        if second_diff < 60:
            return str(int(second_diff)) + " seconds ago"
        if second_diff < 120:
            return "a minute ago"
        if second_diff < 3600:
            return str(int(second_diff / 60)) + " minutes ago"
        if second_diff < 7200:
            return "an hour ago"
        if second_diff < 86400:
            return str(int(second_diff / 3600)) + " hours ago"
    if day_diff == 1:
        return "Yesterday"
    if day_diff < 7:
        return str(day_diff) + " days ago"
    if day_diff < 31:
        return str(int(day_diff / 7)) + " weeks ago"
    if day_diff < 365:
        return str(int(day_diff / 30)) + " months ago"
    return str(int(day_diff / 365)) + " years ago"

app.jinja_env.filters['humanize'] = humanize_ts{% endraw %}

The code for humanize_ts has been picked from here.

Then, you can use the filter in the template.

{% raw  %}<p>Time: {{ article.timestamp | humanize }}</p>{% endraw %}