Group looped entries into blocks and wrap in markup every x number of loops

Question

I am trying to loop through all the entries in a section and "group" them into items which are in blocks of 9 then wrap them with some html markup so there will be the following code:

{% set selectedWork = craft.entries.section('selectedWork') %}

<div class="panel panel--1">
  <article class="img-grid">

    {% for item in selectedWork %}
    <section class="img-grid__item">
      {{ item.title }}
    </section>
    {% endfor %}

  </article>
</div><!-- END .panel -->

The outer <div class="panel panel-1"> and <article> tags need to wrap round the first 9 items then then next 9 etc. etc. Also the panel--1 needs to increment so that each panel goes in order so panel--1 holds 1-9 items then panel--2 holds 9-18 items etc. Is this possible using some kind of array splice or something?

Answer 1

The array slice something you are looking for is Twig's batch filter. Here's how you'd set up the groups and use loop.index to generate the class name.

{# Use the `find()` method to return an array of EntryModels #}
{% set selectedWork = craft.entries.section('selectedWork').find() %}

{# Group entries using the `batch` filter #}
{% set selectedWorkGrouped = selectedWork|batch(9) %}

{% for group in selectedWorkGrouped %}

    {# Set class using the loop index from outer loop #}
    {% set panelClass = 'panel--' ~ loop.index %}

    <div class="panel {{ panelClass }}">

        {% for entry in group %}
            <section class="img-grid__item">
                {{ entry.title }}
            </section>
        {% endfor %}

    </div

{% endfor %}