How to increment a variable on a for loop in jinja template?

Question

I would like to do something like:

variable p is from test.py which is a list [\'a\',\'b\',\'c\',\'d\']

{% for i in p %}
{{variable++}}
{{variable}}
         


        

Answer 1

I was struggle with this behavior too. I wanted to change div class in jinja based on counter. I was surprised that pythonic way did not work. Following code was reseting my counter on each iteration, so I had only red class.

{% if sloupec3: %}
    {% set counter = 1 %}
    {% for row in sloupec3: %}
        {% if counter == 3 %}
            {% set counter = 1 %}        
        {% endif %} 

        {% if  counter == 1: %}
           
 some red div 
        {% endif %} 

        {% if counter == 2: %}
           
 some gray div 
        {% endif %} 

        {% set counter = counter + 1 %} 

    {% endfor %}

{% endif %}

I used loop.index like this and it works:

{% if sloupec3: %}

    {% for row in sloupec3: %} 

        {% if  loop.index % 2 == 1: %}
           
 some red div 
        {% endif %} 

        {% if loop.index % 2 == 0: %}
           
 some gray div 
        {% endif %}  

    {% endfor %}

{% endif %}