Filter Collection Items by page metadata

Question

Context

I have a jekyll collection called product-categories in which each file has the following metadata in front matter:

_product-categories/filename1.md

---
- title
- uuid
---

I have a page whose front matter contains filenames from this collection (collection array selections are saved by their filenames with front matter)...

page.html

---
product-categories:
  - filename1
  - filename2
---
[list of product-categories to be displayed here]

Goal

I want to display the title (from the collection metadata) of these product-categories on the page. Since the items are saved in the front matter by their filename, shouldn't this be possible?

Answer 1

You can do like this :

{% comment %} --- Get product-categories collection's datas --- {% endcomment %}
{% assign collection = site.collections | where: "label", "product-categories" | first %}

{% comment %} --- collection's docs root path --- {% endcomment %}
{% assign collection_path = collection.relative_directory | append: "/" %}

<ul>
{% for cat in page.product-categories %}

  {% comment %} --- expected file path --- {% endcomment %}
  {% assign filepath = collection_path | append: cat | append:".md" %}

  {% comment %} Look for files that have path == filepath.
                As "where" filter return an array,
                we pick the first and only item in array  {% endcomment %}
  {% assign file = site.product-categories | where:"path", filepath | first %}

  {% if file %}
    <li>{{ file.title }}</li>
  {% else %}
    {% comment %} --- error in front matter list ---{% endcomment %}
    <li>No file match for <strong>{{ cat }}</strong> : file at <strong>{{ filepath }}</strong> not found</li>
  {% endif %}

{% endfor %}
</ul>