I am trying to select a few specific items from a collection in Jekyll. I managed to do so with the following code:
{% for paper in site.papers %}
{% if paper.paper-id == "Trott2010" %}
[{{ paper.title }}]({{ paper.url }})
{% endif %}
{% endfor %}
but is not at all elegant. Looking around i found this StackOverflow question and the answer seems exactly what I need:
{% assign paper = site.papers | where:"Trott2010", page.paper-id | first %}
This works as expected if I only use it once per page. Unfortunately if I want to get more than one paper prom site.papers (assigning it to variables with different names), it does not work and I really don't understand way. If I use
{% assign paper1 = site.papers | where:"Trott2010", page.paper-id | first %}
[{{ paper1.title }}]({{ paper1.url }})
{% assign paper2 = site.papers | where:"Scousa2013", page.paper-id | first %}
[{{ paper2.title }}]({{ paper2.url }})
the output is exactly the same in the two instance.
Any help is appreciated.
where selects all the objects in an array where the key has the given value (array | where: "key", "value"). So in your case it should be:
{% assign paper1 = site.papers | where: "paper-id", "Trott2010" | first %}
[{{ paper1.title }}]({{ paper1.url }})
{% assign paper2 = site.papers | where:"paper-id", "Scousa2013" | first %}
[{{ paper2.title }}]({{ paper2.url }})
Related
On the frontpage of my site, I display the newest few posts:
{% for post in posts limit: 6 %}
...
{% endfor %}
This works fine.
Recently I've been going back and editing some old posts, and I want them to show in this list on the frontpage.
I don't want to change their date. Instead, I've been adding a new lastUpdated variable to each post as I edit it, with the date I edited it.
layout: example
lastUpdated: 2020-09-07
---
So now I want to modify the code on my frontpage so that it sorts by lastUpdated if a post has it, and otherwise it should sort by date.
I tried this:
{% assign posts = site.posts
| reverse
| sort: "lastUpdated"
| reverse %}
{% for post in posts limit: 6 %}
...
{% endfor %}
I thought that worked, but it turns out that it's sorting all of the edited posts (the posts that contain lastEdited variables) to the front, followed by newly created posts. I want the edited posts and the newly created posts to both show up in this list, based on their "modified" date.
I tried this:
{% assign posts = site.posts
| sort: "lastUpdated or date" %}
{% for post in posts limit: 6 %}
...
{% endfor %}
But that gives me the posts in the default order, presumably because "lastUpdated or date" is not a valid property.
I also tried this:
{% assign posts = site.posts
| sort: "lastUpdated" or "date" %}
{% for post in posts limit: 6 %}
...
{% endfor %}
But not surprisingly, this is a syntax error.
Is there a simple way to do this that I'm missing?
As soon as I wrote this, I nerd-sniped myself into cobbling together a solution that creates two arrays, and then merges them together based on the lastUpdated and date variables.
{% assign createdPosts = site.posts %}
{% assign updatedPosts = site.posts | sort: "lastUpdated" | reverse %}
{% assign createdIndex = 0 %}
{% assign updatedIndex = 0 %}
{% for i in (1..10) %}
{% assign createdDate = createdPosts[createdIndex].date | date: "%Y-%m-%d" %}
{% assign updatedDate = updatedPosts[updatedIndex].lastUpdated | date: "%Y-%m-%d" %}
{% if createdDate > updatedDate or updatedDate == nil %}
// HTML for createdPosts[createdIndex]
{% assign createdIndex = createdIndex | plus:1 %}
{% else %}
// HTML for updatedPosts[updatedIndex]
{% assign updatedIndex = updatedIndex | plus:1 %}
{% endif %}
{% endfor %}
One thing to note is that I couldn't compare date and lastUpdated directly, because I got this error: comparison of Date with Time failed, so I had to convert them both to strings.
This feels pretty complicated, so I might end up going back and populating every post with lastUpdated to keep it simple.
I am attempting to create a related posts section. I have used loops and conditionals to achieve this before, but I wanted a more efficient and cleaner method. I used include variables to achieve a similar result, but for whatever reason if I attempt to use a post's front matter, I get an empty result. Example:
---
categories:
- Featured
---
{% assign featured-posts = site.posts | where: "categories", page.categories %}
{% assign featured-posts = site.posts | where: "categories", page.categories %}
where filter looks for a string in a string or in an array.
Here page.categories is an array to look for in an array. This will return an empty array.
My shortest way to get related posts with at least one common category.
{% assign related-posts = "" | split: "" %}
{% for c in page.categories %}
{% assign related-posts = related-posts | concat: site.categories[c] | uniq %}
{% endfor %}
jekyll 2.4.0, Mac 10.12.5
{% for year_of_interest in (1997..2017) reversed %}
<large_year>{{year_of_interest}}</large_year>
{% for paper in site.data.publications | where,'site.data.publications.Year',year_of_interest %}
<div class="publication_card">
<a class="article_title" href="../../{{paper.Link}}" title="{{paper.Abstract}}">{{paper.Title}}</a>
</div>
<div class="paper_author_container">
<span class="paper_authors">{{paper.Author | upcase}}</span>
<br>
<span class="journal_info">{{paper.Year}}—{{paper.Journal | upcase}}</span>
<button class="btn" data-clipboard-text="{{paper.BibTex}}">
BIBTEX
</button>
</div>
{% endfor %}
{% endfor %}
The input CSV has this shape and the Year is a simple number:
Title,Link,Abstract,Author,BibTex,Year,Journal,SupplementalLink
background: I'm stuck! I have a CSV where each row represents publication metadata for papers from 1997 to 2016. Some years have many papers, but each year has at least 1 publication. I want a header for each year, and the publications to be posted below. Unfortunately, the where filter does not find any of the articles for a given year in the for loop.
Current functionality: under each header, it shows a list of ALL publications.
Desired: it should only show publications where the paper.Year == year_of_interest.
Thanks in advance!
Three problems here :
You can't filter in a loop
{% for paper in site.data.publications | where,'site.data.publications.Year', year_of_interest %}
Will not work as expected because it always returns all datas.
{% assign filtered = site.data.publications | where,'site.data.publications.Year', year_of_interest %}
{% for paper in filtered %}
Will work, but not now ...
Where filter filters on a key
It's not {% site.data.publications | where,'site.data.publications.Year', year_of_interest %}
but : {% site.data.publications | where,'Year', year_of_interest%}}
Nearly working ...
CSV datas are strings
{{ site.data.publications[0].Year | inspect }} returns "1987" and double quotes around signifies that its a string and that your filter, looking for an integer as "Year" value will never find it. You have to look for a string instead.
To cast an integer into a string you can append an empty string to it.
{% for year_of_interest in (1997..2017) reversed %}
{% comment %} casting an integer to a string {% endcomment %}
{% assign yearAsString = year_of_interest | append:"" %}
{% comment %} filtering datas {% endcomment %}
{% assign selectedEntries = site.data.publications | where: "Year", yearAsString %}
{% for paper in selectedEntries %}
Now, it does the job.
Notes :
1 - Use the | inspect filter to debug, it's useful to determine type of value (string, integer, array, hash).
2 - You can also cast a string to an integer by adding zero to it :
{% assign numberAsString = "1997" %}
{{ numberAsString | inspect }} => "1997"
{% assign numberAsInteger = numberAsString | plus: 0 %}
{{ numberAsInteger | inspect }} => 1997
This is the only documentation for the where filter because it is not a default liquid filter.
https://gist.github.com/smutnyleszek/9803727
site.data.publication.Year is an object of site.data.publications I believe you only need to specify "Year" This is case sensitive by the way.
{% for paper in site.data.publications | where, "Year", year_of_interest %}
I would like to organize a page based on the number of pages that pass a filter.
I have tried to append truthy pages to a collection but it doesn't work.
{% assign homepage_posts = [] %}
{% for my_page in site.pages %}
{% if my_page.homepage %}
{% assign homepage_posts = homepage_posts | concat: [my_page] %}
{% endif %}
{% endfor %}
<h1>size{{homepage_posts.size}}</h1>
<h1>{{homepage_posts}}</h1>
This is not working. Does concat only work with strings?
Jekyll will use Liquid 4 soon. But, for now, no concat.
In your case you can :
Create an empty array (bracket notation doesn't work in liquid) : {% assign homepage_posts = "" | split:"/" %}
{{ homepage_posts | inspect }} --> output : []
And push elements in it :
{% for my_page in site.pages %}
{% if my_page.homepage %}
{% assign homepage_posts = homepage_posts | push: mypage %}
{% endif %}
{% endfor %}
{{ homepage_posts | inspect }}
concat filter only works with arrays and will be available in Jekyll when it upgrades to Liquid 4.*:
concat
Concatenates (combines) an array with another array. The resulting
array contains all the elements of the original arrays. concat will
not remove duplicate entries from the concatenated array unless you
also use the uniq filter.
To filter pages containing a specific attribute (in this case homepage: true) you can use a where filter.
Having a page with front matter:
---
homepage: true
---
Then you can have the pages with the homepage: true attribute like:
{% assign homepages = site.pages | where:"homepage","true" %}
In Jekyll's Front Matter, is there a way to make references to another document?
I have a custom collection, and would like to add meta-data in each document such as "parent-topic" (a link to the parent), and "children" (an array of documents), or "related-topics".
With such a reference I could access the linked documents' meta-data, such as their title, url, or other arbitrary data.
The idea is a hierarchy of documentation, with topics, sub-topics, sub-sub-topics, etc. And a topic page could show a list of child topics, or a breadcrumb for the parent topics, etc.
Real question that deserve a real answer. I also got this documentation problem. Following advise from Ben Balter, I started to use collections. The idea was to make
a table of content reflecting topic/sub-topics arrangement,
a breadcrumb on each page
I gave up because it was simplest to code against pages. So, here's how I do documentation with pages.
Prerequisites :
documentation is in a folder eg : documentation
permalink is set to pretty in _config.yml
folders hierarchy describes documentation organization
example
documentation
|--index.html
|--chapter-1
| |--index.html
|
|--chapter-2
| |--index.html
| |
| |--part-1
| | |--index.html
| | |--subpart-1
| | |--index.html
| |--part-2
| | |--index.html
| |
| |--part-3.html
Note : documentation/chapter-2/part-2/index.html can also be documentation/chapter-2/part-2.html, because permalink is set to pretty, generated page will be at documentation/chapter-2/part-2/index.html.
Pages at a same level are sorted depending on a weight front matter variable. This can be anything you want.
Numbering by tenth allows easy insertion for new doc.
example front matter
---
title: My title
weight: 10
---
documentation get default variables values from _config.yml
example
defaults:
-
scope:
path: "documentation"
type: pages
values:
isDoc: true # allows quick extraction from site.pages
layout: page
Once those prerequisites are in place, it's easy to print a table of content and a breadcrumb.
Table of content
_includes/show-children.html
{% assign parentDir = include.dir %}
{% if parentDir == nil %}<h1>You must specify a root directory</h1>{% endif %}
{% assign allDocs = include.docs %}
{% if allDocs == nil %}{% assign allDocs = site.pages | sort: "weight" %}{% endif %}
{% assign level = include.level %}
{% if level == nil %}{% assign level = parentDir | remove_first: "/" | split:"/" | size %}{% endif %}
{% assign maxLevel = include.maxLevel %}
{% if maxLevel == nil %}{% assign maxLevel = 100 %}{% endif %}
{% assign nextLevel = level | plus : 1 %}
{% comment %}+++++++++++++++++++++++++++++++++++++++++++++++++
Looking for all page in this path with the same level (siblings)
This avoid to deep recursion and error like :
__ Liquid Exception: Nesting too deep __
+++++++++++++++++++++++++++++++++++++++++++++++++{% endcomment %}
{% assign siblings = "" | split: "/" %}
{% for s in allDocs %}
{% assign sPageLevel = s.url | remove_first: "/" | split:"/" | size %}
{% if sPageLevel == level and s.url contains parentDir %}
{% if s.title %}{% assign siblings = siblings | push: s %}{% endif %}
{% endif %}
{% endfor %}
<ul>
{% for p in siblings %}
<li><a href="{{site.baseurl}}{{p.url}}"{%if p.url == page.url%} class="active"{%endif%}>{{ p.title }}</a>
{% if nextLevel <= maxLevel %}
{% include show-children.html dir=p.dir docs=allDocs level=nextLevel maxLevel=maxLevel %}
{% endif %}
</li>
{% endfor %}
</ul>
{% comment %}+++++++++++++++++++++++++++++++++++++++++++++++++
Because all variables are globales (all includes have the same scope)
we restore level and nextLevel variables to parent values
+++++++++++++++++++++++++++++++++++++++++++++++++{% endcomment %}
{% assign level = level | minus : 1 %}
{% assign nextLevel = nextLevel | minus : 1 %}
Use
This include can be called with several arguments :
dir : root dir to explore (ie : /documentation)
docs : an array of pages - default to site.pages
level: level at which we start printing (/documentation is at level 1,
/documentation/chapter-1 is at level 2, and so on)
Default to 'dir' level
maxLevel: where to stop to print - default to 100
Extracting documentation pages
{% assign documents = site.pages | where: "isDoc", true | sort: "weight" %}
{% assign dir = "documentation" %}
This will print all documentation hierachy
{% include show-children.html dir=dir docs=documents %}
This will start printing at level 2
{% include show-children.html dir=dir docs=documents level=2 %}
This stop printing at level 2
{% include show-children.html dir=dir docs=documents maxLevel=2 %}
On page layout if you just want to print page children you can do :
{% assign documents = site.pages | where: "isDoc", true | sort: "weight" %}
{% assign level = page.dir | remove_first: "/" | split:"/" | size %}
{% assign childrenLevel = level | plus : 1 %}
{% include show-children.html docs=documents dir=page.dir level=childrenLevel %}
Breadcrumb
_includes/breadcrumb.html
{% assign minLevel = include.minLevel %}
{% if minLevel == nil %}{% assign minLevel = 1 %}{% endif %}
<div class="breadcrumb">
<p>You are here : </p>
{% assign documents = site.pages | where: "isDoc", true | sort: "weight" %}
{% include get-parents.html page=page minLevel=minLevel docs=documents %}
<p>{{ page.title }}</p>
</div>
<style type="text/css">
.breadcrumb p { display: inline; }
.breadcrumb p+p+p:before { content:"» "; }
</style>
_includes/get-parents.html
{% assign currentPage = include.page %}
{% assign minLevel = include.minLevel %}
{% assign allDocs = include.docs %}
{% assign pageLevel = currentPage.dir | remove_first: "/" | split:"/" | size %}
{% assign parentLevel = pageLevel | minus: 1 %}
{% if parentLevel >= minLevel %}
{% for p in allDocs %}
{% assign pPageLevel = p.dir | remove_first: "/" | split:"/" | size %}
{% if pPageLevel == parentLevel and currentPage.dir contains p.dir %}
{% include get-parents.html page=p minLevel=minLevel docs=allDocs %}
<p>{{ p.title }}</p>
{% endif %}
{% endfor %}
{% endif %}
Use
Print Documentation > chapter 1 > part 1
{% include breadcrumb.html %}
Print Chapter 1 > part 1
{% include breadcrumb.html minLevel=2 %}
Can it be more simple ?
Working code can be found here.