Access Flask config variable in Jinja

{{ config['MY_CONFIGURATION'] }}
    or
{{ config.MY_CONFIGURATION }}

References :
python - Flask - Accessing the config variable in the template - Stack Overflow

Convert integer to string in Jinja

{{ 12345678|string }}

{{ 1111|int }}

{% if 1111 == '1111' %}

    1111

{% else %}

    2222

{% endif %}

References :
python - Convert integer to string Jinja - Stack Overflow

Execute Python code in Jinja Template

controller.py 

def clever_function():
    return u'HELLO'

app.jinja_env.globals.update(clever_function=clever_function)

view.py 

{{ clever_function() }}

References :

Call a python function from jinja2 - Stack Overflow

Jinja Template include file

Include Files

Hello World

  {% include "parts/introtext" %}

Requiring Files
{% require %} works like {% include %} but doesn't return the output.

{% require "myblocks" %}
{% require "parts/introtext" as introtext %}

Hello World
{% call "divbox", "intro", introtext %}

References :
Reuse Parts | Jinja Documentation