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diff --git a/content/blog/hugo/search.md b/content/blog/hugo/search.md new file mode 100644 index 0000000..d58f51c --- /dev/null +++ b/content/blog/hugo/search.md @@ -0,0 +1,100 @@ +--- +title: Implementing a search feature for my hugo static website +description: A golang webservice to complement hugo +date: 2021-09-19 +tags: +- golang +- hugo +--- + +## Introduction + +When I migrated my personal website from dokuwiki to hugo two years ago, the main feature I lost was a way to search the website content. I used [tags](/tags) to mimic a fraction of this power, but with more and more articles over the years I felt the pressure to finally do something. + +Hugo can easily generate a json index of the website, and according to my google-fu hugo users use javascript solutions to implement search on top of this. I was not satisfied by the idea of having javascript download the whole website index and running searches locally, but I found no alternative. Since I love having a javascript free website I wanted to keep it that way if possible, so I designed an alternative. + +This blog post retraces my steps in programming a custom search feature in golang and hosting it alongside my blog on my personal infrastructure. + +## The design + +Up until now the website was served from a simple nginx configuration. I plan to write a golang webservice, have nginx redirect the `/search` path to it and keep serving all the other paths statically. Having some experience from my work on my [trains webapp](https://git.adyxax.org/adyxax/trains) I had a pretty good idea how to write the http handler, I just needed to figure out three things : +- How to generate the JSON index with the information I need. +- How to make the search page integrate perfectly with the website. +- How to leverage the JSON index and which search algorithm to implement. + +### The JSON index + +There are two things to configure in order to get a JSON index from hugo. The first one is to activate JSON as an output format in `config.toml` : +```toml +[outputs] +home = ["HTML", "RSS", "JSON"] +``` + +The second is to create a `layouts/index.json` template of what the index will contain. Here is mine, if you decide to tweak it you will need to rework the search algorithm accordingly : +```html +{{- $.Scratch.Add "index" slice -}} +{{- range .Site.RegularPages -}} + {{- $.Scratch.Add "index" (dict "title" .Title "description" .Params.description "tags" + .Params.tags "content" .Plain "permalink" .Permalink) -}} +{{- end -}} +{{- $.Scratch.Get "index" | jsonify -}} +``` + +### How to maintain a coherent look + +Since I am writing a golang webservice I can use its HTML templating library. It is handy because hugo uses the same library, but I cannot just reuse my hugo templates since they use hugo functions and api which would be a headache to mimic. One of the main pain points is to be able to reuse the css hugo generates, fingerprint and all. + +In order to solve this I thought about my [custom hugo shortcodes]({{< ref "adding-custom-shortcode-age" >}}) and figured a way to use it to my advantage. I added a content section with a single page in `content/search/_index.md` : +```markdown +--- +title: "Search" +menu: + main: + weight: 1 +layout: single +--- + +What are you looking for ? +``` + +To render this page I wrote the corresponding layout in `layouts/search/single.html` : +```html +{{ define "main" }} + +{{ .Content }} + +{{ print "{{ template \"search\" . }}" }} + +{{ end }} +``` + +And VOILÀ! When building the hugo website, it generates a page that contains a simple and valid html template that I can render : +```html +<!-- headers with css and everything exactly as on every page of the website, + as well as the menu and its section highlighting) --> +<p>What are you looking for ?</p> +{{ template "search" . }} +<!-- the footer --> +``` + +The `search` template just need to be written accordingly, and the http templating library will do the rest. + +### The golang webservice + +The webservice lives in a folder of my hugo repository and can be found [here](https://git.adyxax.org/adyxax/www/src/branch/master/search). The website's makefile first builds the hugo website, then copies the HTML template and the json index in the search folder. It then builds the golang binary and embeds these. + +When the webservice starts, it parses the JSON index and generates separate lists of unique words found in titles, descriptions, tags and page content. These lists each have a weight that factors in the results when the searched words are found in the list via a simple `string.Contains` match. + +It is not very clever but because my website is small it produces pertinent results with this very simple algorithm. A friend pointed to me that Radix Trees are the efficient way to search if a word is part of a text and I plan to look into implementing that one day. + +## Conclusion + +I find that this search feature works well and looks even better! Being light and fast it fits perfectly with my philosophy for this website, and I find that managing a server side service is preferable to pushing the burden to the visitor's browser. + +Future improvements I am considering (beside radix trees) are : +- allow to search for a phrase, right now words are split and handled similarly as if a OR was used. +- allow to request a word be present in the results (right now it is a OR). +- allow to match negatively against a word or pattern. +- permit a verbatim search to prevent substring matches. +- optionally select tags from a list, either positively or negatively. +- maybe factor pages' publishing date as a results sorting option. |