In jinja, the variable loop.index holds the iteration number of the current running loop.
When I have nested loops, how can I get in the inner loop the current iteration of an outer loop?
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3 Answers
Store it in a variable, for example:
{% for i in a %}
{% set outer_loop = loop %}
{% for j in a %}
{{ outer_loop.index }}
{% endfor %}
{% endfor %}
3 Comments
scottydelta
Just note that the index will start from 1 and not 0.
Scott Yang
Also note loop.index0 would let you access index starting from 0 (jinja.pocoo.org/docs/dev/templates/#for)
senaps
what if we wanted to show the loop index as row number in a table? this code here isn't considering that and inner loop will be shown as 1 untill it ends. how we handle that?
@senaps I just changed outer_loop.index to index0 this returns the iteration with a 0 index. So the first item starts with a 0
{% for i in a %}
{% set outer_loop = loop %}
{% for j in a %}
{{ outer_loop.index0 }}
{% endfor %}
{% endfor %}
1 Comment
Yunnosch
Welcome to StackOverflow. Please, edit and try for How to Answer, describe the effect of what you propose and explain why it helps to solve the problem, make the additional insight more obvious which you contribute beyond existing answers, the relevant advantage which your solution achieves, especially if the difference is so small and non-obvious. Consider taking the tour.
You can use loop.parent inside a nested loop to get the context of the outer loop
{% for i in a %}
{% for j in i %}
{{loop.parent.index}}
{% endfor %}
{% endfor %}
This is a much cleaner solution than using temporary variables. Source - http://jinja.pocoo.org/docs/templates/#for
2 Comments
Romz
This is wrong. Jinja doesn't support .parent. See jinja.pocoo.org/docs/tricks/#accessing-the-parent-loop and jinja.pocoo.org/docs/templates/#for.
