Jekyll - creating a gallery with front matter data

Question

I want to create a "list" of tags from data in my post front matter to use with a lightbox plugin.

So, lets say that i have in my post front matter the following:

gallery: true
images:
 - name: image-1.jpg
   alt: image-1
 - name: image-2.jpg
   alt: image-2
 - name: image-3.jpg
   alt: image-3

I want to loop through that data and create the following html:

<img id="thumb01" class="thumbnail" src="/assets/images/image-1.jpg" data-src="/assets/images/image-1.jpg" data-prev="thumb03" data-next="thumb02" alt="image-1">
<img id="thumb02" class="thumbnail" src="/assets/images/image-2.jpg" data-src="/assets/images/image-2.jpg" data-prev="thumb01" data-next="thumb03" alt="image-2">
<img id="thumb03" class="thumbnail" src="/assets/images/image-3.jpg" data-src="/assets/images/image-3.jpg" data-prev="thumb02" data-next="thumb01" alt="image-3">

I was thinking of inserting in the post layout the following:

{% if page.gallery %}
some type of loop
{% endif %}

But i haven't got the slightest of clues on how to achieve that, please help!
thanks!

Answer 1

Try this :

{% if page.gallery == true %}
  {%- for img in page.images -%}

    {% comment %}
      If we have more than one image,
      we calculate next and prev index
    {% endcomment %}
    {% if forloop.length > 1 %}
      {% if forloop.first %}
        {% assign prev = forloop.length %}
      {% else %}
        {% assign prev = forloop.index | minus: 1 %}
      {% endif %}

      {% if forloop.last %}
        {% assign next = 1 %}
      {% else %}
        {% assign next = forloop.index | plus: 1 %}
      {% endif %}
    {% endif %}

<img id="thumb{{ forloop.index }}" class="thumbnail"
     src="{{ site.basurl }}/assets/images/{{ img.name }}"
     data-src="{{ site.basurl }}/assets/images/{{ img.name }}"
     {% comment %} only necessary if we have more than one image {% endcomment %}
     {%- if forloop.length > 1 -%}
     data-prev="thumb{{ prev }}"
     data-next="thumb{{ next }}"
     {%- endif %}
     alt="{{ img.alt }}" >

  {%- endfor -%}
{% endif %}