Yearly Post Archives In Hugo

I spent a little time this weekend creating yearly post archives for my Hugo site.

Hugo already has pagination functionality, but I dislike this approach in blogs. For one thing, it messes up web search. I find an interesting link which Google claims is on page 12 of some blog, but now I must dig to page 14 or 15 or 23.

Years give me a fixed point to anchor my archive listings to. I could narrow it down to years and months, but I am not that prolific. Years will do fine.

Everything On One Page For Each Section

Hugo bases template selection on specificity: use the most specific template if available, otherwise use more general-purpose templates. Right now I lean on my _default layouts for all content. The _default/list.ace template provides the layout for all content collections.

= content main
  h1 {{ .Title }}
  ul.post-list
    {{ range .Data.Pages }}
      li {{ .Render "li" }}
    {{ end }}

Hugo gives the template a title and a collection of pages — along with numerous other variables, and at the other end something like this is produced.

Group Everything By Date

For a first step in the process, let’s see what happens when we tell the Pages to group by date.

= content main
  h1 {{ .Title }}
  {{ range (.Data.Pages.GroupByDate "2006") }}
    h2 {{ .Key }}
    ul.post-list
      {{ range .Pages }}
        li {{ .Render "li" }}
      {{ end }}
  {{ end }}

Not too bad. Let’s move on.

This Year’s Content

Hold on a second. I can use the first function to create a list of things published this year. I’ll put that in my index.ace layout.

= content main
  p This page lists the projects and posts I published on the site this year.
  p This is a blog, so of course you can
    a href="/index.xml"  subscribe via RSS.
  {{ range first 1 (.Data.Pages.GroupByDate "2006") }}
    h2 Posted So Far in {{ .Key }}
    ul.post-list
      {{ range .Pages }}
        li {{ .Render "li" }}
      {{ end }}
  {{ end }}

No matter how hard I tried, I could not find a way to create a page for last year with this technique. Moving on.

Life Hack: Use Taxonomies!

Hugo does not directly support yearly archive pages. However, this Hugo community comment shows that somebody solved a very similar problem using taxonomies.

Taxonomies are special terms you create to organize your content. Categories and tags are a common example across blogs. Hugo simplifies creation of your own taxonomies and their presentation with templates.

Strictly speaking, this is kind of a hack. You would ordinarily put an entry with singular and plural names for your taxonomies in config.yml, but I do not care about pluralization in this case. I just want a way to create “year” templates.

taxonomies:
    year: "year"

In order for this to work, I need every content item to have a year entry in its front matter set to the year that item was published.

year: 2016

This is going to be tedious. Let’s not do this manually, okay?

Here comes the Perl.

Automate The Frontmatter

#!/usr/bin/env perl

use v5.22.0;
use autodie qw(:all);

use File::Find::Rule;
use File::Slurper qw(read_text write_text);
use YAML::Tiny;

sub add_metadata_to {
  my $filename = shift;
  say "Looking at $filename";

  my $original = read_text $filename;
  my ( $empty, $front_matter, $content ) = split /^---$/m, $original;
  my $yaml = YAML::Tiny->read_string( $front_matter );
  my $date = $yaml->[0]{date};

  if ( $date =~ m{^ (?<year> \d\d\d\d) - (?<month> \d\d) - }x ) {
    $yaml->[0]{year} = $+{year};
  }
  else {
    # Avoid converting simple pages.
    return;
  }

  my $new_front_matter = $yaml->write_string;
  my $new_content = $new_front_matter . "---" . $content;
  write_text $filename, $new_content;
  say "Updated $filename metadata";
}

my @files = File::Find::Rule->file()
  ->name( qw( *.md *.html ) )
  ->in( "content" );

add_metadata_to $_ for @files;

Summarize Every Year On One Page

My _default/terms.ace layout was already set up for categories and tags. The reverse alphabetical order was some whimsical experiment that I forgot to change, but it works perfect for years. Reverse alphabetical looks quite a bit like reverse chronological when things are sorted in ASCIIbetical order.

= content main
  h1 {{ .Title }}
  dl
    {{ $data := .Data }}
    {{ range $key, $value := .Data.Terms.Alphabetical.Reverse }}
      dt
        a href="/{{ $data.Plural }}/{{ $value.Name | urlize }}" {{ $value.Name }}
      dd {{ $value.Count }} posts
    {{ end }}

So by adding one little entry to config.yml and making one little edit — okay, write a Perl script to make one little edit to every page in my site — I get a usable yearly archive!

I put _default/list.ace back in its original state, and each year has a simple listing.

What Else?

It would sure be nice to have “next year” / “previous year” links. I can use GroupBy functionality to create distinct craft and blog sections for each year’s listing. For that matter, I could see breaking Crafts and Posts listings down into yearly archives.

You know what? This is good enough for now. I set out to have yearly archive pages. I have yearly archive pages. Time to go out and enjoy an unexpectedly pleasant Seattle Sunday.