How to output loop.counter in python jinja template?

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00:00 Question
00:32 Accepted answer (Score 541)
01:15 Answer 2 (Score 96)
01:45 Answer 3 (Score 29)
02:04 Answer 4 (Score 0)
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Full question
https://stackoverflow.com/questions/1214...

Question links:
[the docs]: https://jinja.palletsprojects.com/en/3.0.../

Accepted answer links:
http://jinja.pocoo.org/docs/templates/

Answer 2 links:
[the official docs]: https://jinja.palletsprojects.com/en/3.0...

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https://meta.stackexchange.com/help/lice...

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Tags
#python #jinja2 #templatingengine

#avk47

ACCEPTED ANSWER

Score 592

The counter variable inside the loop is called loop.index in Jinja2.

>>> from jinja2 import Template

>>> s = "{% for element in elements %}{{loop.index}} {% endfor %}"
>>> Template(s).render(elements=["a", "b", "c", "d"])
1 2 3 4

In addition to loop.index, there is also

loop.index0 (index starting at 0)
loop.revindex (reverse index; ending at 1)
loop.revindex0 (reverse index; ending at 0)
Even more at http://jinja.pocoo.org/docs/templates/.

ANSWER 2

Score 130

Inside of a for-loop block, you can access some special variables, such as loop.index (but not loop.counter). From the official docs:

Variable	Description
`loop.index`	The current iteration of the loop. (1 indexed)
`loop.index0`	The current iteration of the loop. (0 indexed)
`loop.revindex`	The number of iterations from the end of the loop (1 indexed)
`loop.revindex0`	The number of iterations from the end of the loop (0 indexed)
`loop.first`	True if first iteration.
`loop.last`	True if last iteration.
`loop.length`	The number of items in the sequence.
`loop.cycle`	A helper function to cycle between a list of sequences.
`loop.depth`	Indicates how deep in a recursive loop the rendering currently is. Starts at level 1
`loop.depth0`	Indicates how deep in a recursive loop the rendering currently is. Starts at level 0
`loop.previtem`	The item from the previous iteration of the loop. Undefined during the first iteration.
`loop.nextitem`	The item from the following iteration of the loop. Undefined during the last iteration.
`loop.changed(*val)`	True if previously called with a different value (or not called at all).

ANSWER 3

Score 36

If you are using Django, use forloop.counter instead of loop.counter:

<ul>
{% for user in userlist %}
  <li>
      {{ user }} {{forloop.counter}}
  </li>
      {% if forloop.counter == 1 %}
          This is the First user
      {% endif %}
{% endfor %}
</ul>

ANSWER 4

Score 0

Real-life example:

{% for image in item['images'] %}
    {% set image_id = item_id ~ '-preview-' ~ loop.index0 %}
    <div id="{{ image_id }}" class="overlay">
        <a class="cancel" href="#{{ item_id }}"></a>
        <div class="popup">
            {% set src = image if image.startswith('http') else '/static/images/store/' ~ item_id ~ '/' ~ image %}
            <a href="{{ src }}"><img class="modal-img" src="{{ src }}"/></a>
        </div>
    </div>
{% endfor %}