CODEWITHSUNDEEP
pythonjinja2templating-engine
Rolando
Rolando

Reputation: 62704

How to output loop.counter in python jinja template?

I want to be able to output the current loop iteration to my template.

According to the docs, there is a loop.counter variable that I am trying to use:

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

But is being outputed to my template. What is the correct syntax?

Upvotes: 294

Views: 338621

Answers (4)

tozCSS
tozCSS

Reputation: 6134

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).

Upvotes: 137

Daniel Butler
Daniel Butler

Reputation: 3756

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>

Upvotes: 36

Elijah
Elijah

Reputation: 2223

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 %}

Upvotes: 0

sigi
sigi

Reputation: 6279

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

Upvotes: 594

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