Single Index Blog Post for Multiple Series Posts in Jekyll - jekyll

Question

I have several blog posts that fall under one umbrella blog post. For example, I have several posts about SQL Zoo tutorials, but I want to be able to link them all up to one "umbrella" post so that I only have one SQL Zoo post on the index page of my blog. I got this idea from: https://codeasashu.github.io/implement-series-post-jekyll-part-2/ and tried to follow the instructions, but now my series post does not show up on my index page. I have the following code in a file called post-series.html located in my _includes folder:
{% assign seriesarray = '|' | split : '|' %}
{% assign seriestitle = '' %}
{% assign serieslabel = '' %}
{% assign sortedposts = (site.posts | sort: 'date') %}
{% for post in sortedposts %}
{% if post.series and page.series_slug != nil and post.series == page.series_slug %}
{% capture postitem %} <li> {{ post.title }} </li> {% endcapture %}
{% assign seriesarray = seriesarray | push: postitem %}
{% assign seriestitle = 'Posts in this series' %}
{% assign serieslabel = 'Series Post' %}
{% elsif post.series != nil and page.series != nil and page.series == post.series %}
{% assign pageurl = page.url | split:'/' | last %}
{% assign posturl = post.url | split:'/' | last %}
{% if pageurl != posturl %}
{% capture postitem %} <li> {{ post.title }} </li> {% endcapture %}
{% else %}
{% capture postitem %} <li> {{ post.title }} </li> {% endcapture %}
{% endif %}
{% assign seriesarray = seriesarray | push: postitem %}
{% endif %}
{% if post.series_slug != nil and page.series != nil and page.series == post.series_slug %}
{% capture series_title %} {{ post.title }} {% endcapture %}
{% assign seriestitle = 'This posts is part of series - ' | append: series_title %}
{% assign serieslabel = 'This posts is part of series - ' | append: series_title %}
{% endif %}
{% endfor %}
{% capture serieslayout %}
{% if seriesarray.size > 0 %}
<hr />
<div class="panel">
<div class="panel-body">
<h4> {{ seriestitle }} </h4>
<ul id="post-series-list">
{% endif %}
{% for post in seriesarray %} {{ post }} {% endfor %}
{% if seriesarray.size > 0 %} </ul> </div> </div> {% endif %}
{% endcapture %}
and the following code from my index.html file in the root of my directory:
---
layout: index
---
<div id="home">
<h1>{{ site.title }}</h1>
<hr />
<ol class="posts">
{% for post in paginator.posts %}
{% assign seriesPost = nil %}
{% if post.series == nil %}
{% if post.series_slug != nil %} {% assign seriesPost = '(Series)' %} {% endif %}
<li class="post-listing">
<img class="post__image" src="/static/img/{{ post.cover_image}}" alt="{{ post.cover_alt }}" />
<div class="post__text">
<a class="post__title" href="{{ post.url }}">{{ post.title }}</a><br>
<span>
{{ post.date | date_to_string }} •
{% assign words = post.content | number_of_words %}
{% if words < 360 %}
1 min read
{% else %}
{{ words | divided_by:180 }} min read
{% endif %}
</span>
{{ post.excerpt }}
</div>
</li>
{% endif %}
{% endfor %}
</ol>
<!-- <div class="sidebar-right sidebar"></div> -->
<!-- <ul>
{% for post in paginator.posts %}
<li>
{{ post.title }}
{{ post.excerpt }}
</li>
{% endfor %}
</ul> -->
<!-- Pagination links -->
{% if paginator.total_pages > 1 %}
<ul class="pagination pagination-sm">
{% if paginator.previous_page %}
<li>«</li>
{% else %}
<li class="disabled"><span aria-hidden="true">«</span></li>
{% endif %}
<li>First</li>
{% for page in (1..paginator.total_pages) %}
{% if page == paginator.page %}
<li class="active"><a>{{ page }}<span class="sr-only">(current)</span></a></li>
{% elsif page == 1 %}
<li>{{ page }}</li>
{% else %}
<li>{{ page }}</li>
{% endif %}
{% endfor %}
<li>Last</li>
{% if paginator.next_page %}
<li>»</li>
{% else %}
<li class="disabled"><span>»</span></li>
{% endif %}
</ul>
{% endif %}
</div><!-- end #home -->
My full repo can be found here: https://github.com/thedatasleuth/thedatasleuth.github.io

Answer 1

In your index.html, {% if post.series == nil %} simply bares posts containing a series: someserie front matter variable to be printed.
For the second problem (note that on SO, you are supposed to ask one question at a time) :
Umbrella post always have series_slug: "My serie slug" in front
matter.
Serie's posts always have series: "My serie slug" in front
matter, and this must be strictly equal to umbrella page series_slug. (eg : you have a post with published: false and series: "SQL Zoology" that will not appear in SQL Zoo serie if you publish it.)
In _layouts/post.html remove {% include series.html %}.
In _includes/post-series.html replace all your code by the following :
{% comment %} #### On an umbrella page {% endcomment %}
{% if page.series_slug != nil %}
{% assign key = page.series_slug %}
{% assign title = page.title %}
{% assign url = page.url %}
{% assign sentence = "All posts in this serie :" %}
{% endif %}
{% comment %} #### On a serie page {% endcomment %}
{% if page.series != nil %}
{% assign key = page.series %}
{% assign umbrella_page = site.posts | where: 'series_slug', key | first %}
{% assign title = umbrella_page.title %}
{% assign url = umbrella_page.url %}
{% assign series_posts = site.posts | where: "series", key %}
{% for post in series_posts %}
{% if post.url == page.url %}
{% assign idx = forloop.index %}
{% endif %}
{% endfor %}
{% capture sentence %}
This article is <strong>Part {{ idx }}</strong> in a <strong>{{ series_posts.size }}-Part</strong> in {{ title }} serie
{% endcapture %}
{% endif %}
{% if page.series_slug != nil or page.series != nil %}
{% assign series_posts = site.posts | where: "series", key %}
<hr />
<div class="panel">
<div class="panel-body">
{% if page.series_slug != nil %}
{% assign key = page.series_slug %}
{% assign title = page.title %}
{% assign url = page.url %}
{% endif %}
<h4>{{ sentence }}</h4>
<ul id="post-series-list">
{% for post in series_posts %}
<li>
{% if page.url == post.url %}
This post : {{ post.title }} - part {{ forloop.index }}
{% else %}
{{ post.title }} - part {{ forloop.index }}
{% endif %}
</li>
{% endfor %}
</ul>
</div>
</div>
{% endif %}

Answer 2

The problem you are facing
You forgot to add the series and series_slug YML variables. That is why it is not working in your case. You seem to not fully understand how the code works, probably due to the complexity of the solution. Therefore, I added another (much simpler) solution, that might fit your needs equally well.
A better/simpler solution
Simply add a YML variable called group: groupname to each post you want in a group. Do NOT skip any of the posts during pagination. Next, list the posts with the same group on the footer of each post (in your page/post layout) with the code below. Finally, add 'part 1', 'part 2', etc. to the post names in the series.
{% if post.group != nil %}
<ul>
{% for post in site.posts %}
{% if post.group == page.group %}
<li>{{ post.title }}</li>
{% endif %}
{% endfor %}
</ul>
{% endif %}
PS. If you really want to skip some posts in the pagination, I would create an universal solution. Add a skip_pagination boolean to the Front Matter (YML) and see if it is true in the pagination loop. This enables you to skip any post in the paginator.