Sorted navigation menu with Jekyll and Liquid

Question

I'm constructing a static site (no blog) with Jekyll/Liquid. I want it to have an auto-generated navigation menu that lists all existing pages and highlight the current page. The items should be added to the menu in a particular order. Therefore, I define a weight property in the pages' YAML:

---
layout : default
title  : Some title
weight : 5
---

The navigation menu is constructed as follows:

<ul>
  {% for p in site.pages | sort:weight %}
    <li>
      <a {% if p.url == page.url %}class="active"{% endif %} href="{{ p.url }}">
        {{ p.title }}
      </a>
    </li>
  {% endfor %}
</ul>

This creates links to all existing pages, but they're unsorted, the sort filter seems to be ignored. Obviously, I'm doing something wrong, but I can't figure out what.

Solution 1

Since Jekyll 2.2.0 you can sort an array of objects by any object property. You can now do :

{% assign pages = site.pages | sort:"weight"  %}
<ul>
  {% for p in pages %}
    <li>
      <a {% if p.url == page.url %}class="active"{% endif %} href="{{ p.url }}">
        {{ p.title }}
      </a>
    </li>
  {% endfor %}
</ul>

And save a lot of build time compared to @kikito solution.

edit: You MUST assign your sorting property as an integer weight: 10 and not as a string weight: "10".

Assigning sorting properties as string will ends up in a a string sort like "1, 10, 11, 2, 20, ..."

Solution 2

Your only option seems to be using a double loop.

<ul>
{% for weight in (1..10) %}
  {% for p in site.pages %}
    {% if p.weight == weight %}
      <li>
        <a {% if p.url == page.url %}class="active"{% endif %} href="{{ p.url }}">
          {{ p.title }}
        </a>
      </li>
    {% endif %}
  {% endfor %}
{% endfor %}
</ul>

Ugly as it is, it should work. If you also have pages without a weight, you will have to include an additional internal loop just doing {% unless p.weight %} before/after the current internal one.

Solution 3

Below solution works on Github (doesn't require a plugin):

{% assign sorted_pages = site.pages | sort:"name" %}
{% for node in sorted_pages %}
  <li><a href="{{node.url}}">{{node.title}}</a></li>
{% endfor %}

Above snippet sorts pages by file name (name attribute on Page object is derived from file name). I renamed files to match my desired order: 00-index.md, 01-about.md – and presto! Pages are ordered.

One gotcha is that those number prefixes end up in the URLs, which looks awkward for most pages and is a real problem in with 00-index.html. Permalilnks to the rescue:

---
layout: default
title: News
permalink: "index.html"
---

P.S. I wanted to be clever and add custom attributes just for sorting. Unfortunately custom attributes are not accessible as methods on Page class and thus can't be used for sorting:

{% assign sorted_pages = site.pages | sort:"weight" %} #bummer

Solution 4

I've written a simple Jekyll plugin to solve this issue:

1. Copy sorted_for.rb from https://gist.github.com/3765912 to _plugins subdirectory of your Jekyll project:

   module Jekyll
     class SortedForTag < Liquid::For
       def render(context)
         sorted_collection = context[@collection_name].dup
         sorted_collection.sort_by! { |i| i.to_liquid[@attributes['sort_by']] }
   
         sorted_collection_name = "#{@collection_name}_sorted".sub('.', '_')
         context[sorted_collection_name] = sorted_collection
         @collection_name = sorted_collection_name
   
         super
       end
   
       def end_tag
         'endsorted_for'
       end
     end
   end
   
   Liquid::Template.register_tag('sorted_for', Jekyll::SortedForTag)
   

2. Use tag sorted_for instead of for with sort_by:property parameter to sort by given property. You can also add reversed just like the original for.
3. Don't forget to use different end tag endsorted_for.

In your case the usage look like this:

<ul>
  {% sorted_for p in site.pages sort_by:weight %}
    <li>
      <a {% if p.url == page.url %}class="active"{% endif %} href="{{ p.url }}">
        {{ p.title }}
      </a>
    </li>
  {% endsorted_for %}
</ul>

Solution 5

The simplest solution would be to prefix the filename of your pages with an index like this:

00-home.html 01-services.html 02-page3.html

Pages are be ordered by filename. However, now you'll have ugly urls.

In your yaml front matter sections you can override the generated url by setting the permalink variable.

For instance:

---
layout: default
permalink: index.html
---

View more solutions

Comments

[kikito]

lol. I guess you can trim that down by compressing everything into one single line of code if that is a concern. Unfortunately liquid doesn't have a {%- %} prefix to collapse empty lines like erb.

[flyx]

Nice one! Still a hack, but much simpler than the other answers.

[Christiaan]

Be careful with this if you push your site to github pages. For some reason the ordering will be messed up then. See also: github.com/plusjade/jekyll-bootstrap/issues/…

[Paul Wagland]

Just a pity that you can't use custom plugins with GitHub pages… :-\

[Markus Amalthea Magnuson]

Just an addition: Replacing (1..10) with (1..site.pages.size) makes this loop as short as possible, and will work regardless of how many pages you have. Thanks for a stupid yet highly clever hack :)

[kikito]

@MarkusAmaltheaMagnuson the (1..10) on this code represent possible weights. It could be replaced by (1..MAX_WEIGHT) to make it a bit more clear (and have MAX_WEIGHT defined somewhere else, like in a constants file).

[MisterMetaphor]

Nice, thanks for sharing. Just a little addition: in case not all of your items have the specified property, you can alter the sort_by! call to ignore those items: sorted_collection.sort_by! { |i| i.to_liquid[@attributes['sort_by']] || 0 } (replace 0 with infinity if you want it the other way around).

[sdmeyers]

Suddenly this started throwing errors on _post pages: Liquid Exception: comparison of Hash with Hash failed in _posts/...

[Adam B]

You good sir deserve a medal. I was just about to resort to generating my site locally and pushing the static HTML to GitHub to be able to use plugins to do this.

[user1020853]

This worked for me, except that the "active" class needed to go on the <li> instead of the <a>

[brenna]

Would this work for sorting by full file path? i.e. {% assign sorted_pages = site.pages | sort:"path" %} and 00-directory/00-file.md would come before 01-anotherDir/00-anotherFile.md

[brenna]

It does work! Thanks so much! I've been fighting with this for days.

[groundh0g]

This worked like a charm for me. If you're on GitHub Pages, this is the answer you're looking for. Of course, I only have 5 nav items, so it's probably overkill to solve with code change. I have two variants of the same site, though. My OCD insisted that their link orders match. :P

[lfk]

This is the cleanest solution; there's just a slight error -- the sort key should be given as a string, i.e. sort: 'weight'. Updated the sample code.

[lfk]

The aforementioned issue is mentioned and resolved here. It might take a while before the versions running GitHub pages are updated, though.

[destan]

Hi @Wojtek sort:"weight" just works for me, fyi. By the way thanks for the excellent solution.

[Paul Ferrett]

This is one of the best things about Jekyll/static-generation - "ugly" as it may be, it only runs once which doesn't affect the user experience or server load. Nice solution!

[jupiteror]

@WingLeong I didn't do any tests but that's what worked out for me.

[wedi]

Sorting by weight does work! See answer below Maybe that was changed in Jekyll.

[eyettea]

does not work for me (Jekyll 2.4.0). I defined the weight property in the pages as said above, but the sort seems to ignore it.

[David Jacquel]

@eyetea you are right. We need to make an assignment first. I've editer my code and it works on Jekyll 2.4.0. ;-)

[eyettea]

Thanks for the help. I also edited the code and removed the second sort filter, since it looks like it's not needed anymore.

[David Jacquel]

You're right. I've edited it myself because your suggested edit was rejected by 3 users ???

[eyettea]

strange, I just deleted the "| sort: weight"... Why would it be rejected? Anyway, problem solved.

[Dominik]

I get an error in 2.4.0: Error: comparison of Jekyll::Page with Jekyll::Page failed .... ?

[Dominik]

mh turns out you can't use decimal numbers like 2.1 as weight... :) have to put them into quotes. Thanks though