Include a file, but only if it exists? - jekyll

Question

I'm creating a style guide in Jekyll and using Collections to define different elements of the guide. For example, headings, lists, etc.
I'm trying to separate the Sass into files that match up with the partials, one to one, and I'd like to render the Sass files as part of each collection.
So, something like:
{% if _includes/_sass/{{ entry.title | append: ".scss"}} %}
{% highlight sass %}
{% include _includes/_sass/{{ entry.title | append: ".scss" }} %}
{% endhighlight %}
{% endif %}
Basically, what I want is "Include a file in this directory that has the same name as this entry in my collection. If it doesn't exist, don't break."
How do I do this? I've explored storing the file path in a variable but can't seem to get that to work.
Thanks in advance.

Answer 1

It can be done.
This works on Jekyll 3 but it can certainly be ported to Jekyll 2.
Starting from a base install (jekyll new)
_config.yml
collections:
guide:
sasssamples:
Style guide files
Our samples will be grouped in the _guide collection.
Example file : _guide/header/header1.hmtl
---
title: Header level 1
---
<h1>Header level 1</h1>
SCSS samples
We want our SCSS samples to be included in our css/main.scss and use variables defined in our other SCSS files. Our samples will be integrated at the end of our css/main.scss
We don't want our SCSS samples to render as css so no .scss extension. Switch to .txt extension
We want to access SCSS samples from a list. Let's put them in a sasssamples collection.
Example file : _sasssamples/header/header1.txt
---
---
h1{
color: $brand-color;
border: 1px solid $brand-color;
}
SCSS samples integration
Add this code at the very end of you bootstraping scss file (css/main.scss on a base Jekyll install)
css/main.scss
[ original code ... ]
{% comment %} Selecting a collection the Jekyll 3 way. See https://github.com/jekyll/jekyll/issues/4392 {% endcomment %}
{% assign scssCollection = site.collections | where: 'label', 'sasssamples' | first %}
{% comment %}
Printing documents in sasssamples collection.
All SCSS from style guide are sandboxed in .guide class
This allows us to apply styles only to style guide html samples
{% endcomment %}
.guide{
{% for doc in scssCollection.docs %}
{{ doc.content }}
{% endfor %}
}
The style guide
<h2>Style guide</h2>
{% comment %}Selecting a collection the Jekyll 3 way. See https://github.com/jekyll/jekyll/issues/4392 {% endcomment %}
{% assign guideCollection = site.collections | where: 'label', 'guide' | first %}
{% assign scssCollection = site.collections | where: 'label', 'sasssamples' | first %}
{% comment %} Looping hover style guide samples {% endcomment %}
{% assign samples = guideCollection.docs %}
{% for sample in samples %}
<article>
<h3>Element : {{ sample.title }}</h3>
<h4>Render</h4>
<div class="guide">
{{ sample.content }}
</div>
<h4>html code</h4>
{% highlight html %}{{ sample.content }}{% endhighlight %}
{% comment %}
Changing a path like : _guide/headers/header1.html
to : _sasssamples/headers/header1.txt
{% endcomment %}
{% assign scssPath = sample.path | replace: '_guide', '_sasssamples' %}
{% assign scssPath = scssPath | replace: '.html', '.txt' %}
{% comment %} Try to find a SCSS sample with equivalent path {% endcomment %}
{% assign scssSample = scssCollection.docs | where: 'path', scssPath | first %}
{% comment %}We print SCSS sample only if we found an equivalent path{% endcomment %}
{% if scssSample != nil %}
<h4>SCSS code</h4>
{% highlight css %}{{ scssSample.content }}{% endhighlight %}
{% endif %}
</article>
{% endfor %}
Done!

Answer 2

Seems it only miss on assigning the correct path
{% if _includes/_sass/{{ entry.title | append: ".scss"}}
Need to be replaced to relative path to the scss file:
{% assign scssPath = 'relative/path/to/your/scss/' %}
{% if {{ entry.title | append: ".scss" | prepend: scssPath }} != nil %}