Data-driven Content

Data-driven content with a static site generator? Yes, it is possible!

In addition to the data files feature, we have also implemented the feature “Data-driven Content”, which lets you load any JSON or CSV file from nearly any resource.

“Data-driven Content” currently consists of two functions, getJSON and getCSV, which are available in all template files.

Implementation details

Calling the functions with an URL

In any HTML template or Markdown document, call the functions like this:

{{ $dataJ := getJSON "url" }}
{{ $dataC := getCSV "separator" "url" }}

or, if you use a prefix or postfix for the URL, the functions accept variadic arguments:

{{ $dataJ := getJSON "url prefix" "arg1" "arg2" "arg n" }}
{{ $dataC := getCSV  "separator" "url prefix" "arg1" "arg2" "arg n" }}

The separator for getCSV must be put in the first position and can only be one character long.

All passed arguments will be joined to the final URL; for example:

{{ $urlPre := "https://api.github.com" }}
{{ $gistJ := getJSON $urlPre "/users/GITHUB_USERNAME/gists" }}

will resolve internally to:

{{ $gistJ := getJSON "https://api.github.com/users/GITHUB_USERNAME/gists" }}

Finally, you can range over an array. This example will output the first 5 gists for a GitHub user:

<ul>
  {{ $urlPre := "https://api.github.com" }}
  {{ $gistJ := getJSON $urlPre "/users/GITHUB_USERNAME/gists" }}
  {{ range first 5 $gistJ }}
    {{ if .public }}
      <li><a href="{{ .html_url }}" target="_blank">{{ .description }}</a></li>
    {{ end }}
  {{ end }}
</ul>

Example for CSV files

For getCSV, the one-character long separator must be placed in the first position followed by the URL.

<table>
  <thead>
    <tr>
    <th>Name</th>
    <th>Position</th>
    <th>Salary</th>
    </tr>
  </thead>
  <tbody>
  {{ $url := "http://a-big-corp.com/finance/employee-salaries.csv" }}
  {{ $sep := "," }}
  {{ range $i, $r := getCSV $sep $url }}
    <tr>
      <td>{{ index $r 0 }}</td>
      <td>{{ index $r 1 }}</td>
      <td>{{ index $r 2 }}</td>
    </tr>
  {{ end }}
  </tbody>
</table>

The expression {{index $r number}} must be used to output the nth-column from the current row.

Caching of URLs

Each downloaded URL will be cached in the default folder $TMPDIR/hugo_cache/. The variable $TMPDIR will be resolved to your system-dependent temporary directory.

With the command-line flag --cacheDir, you can specify any folder on your system as a caching directory.

You can also set cacheDir in the main configuration file.

If you don’t like caching at all, you can fully disable caching with the command line flag --ignoreCache.

Authentication when using REST URLs

Currently, you can only use those authentication methods that can be put into an URL. OAuth or other authentication methods are not implemented.

Loading local files

To load local files with the two functions getJSON and getCSV, the source files must reside within Hugo’s working directory. The file extension does not matter but the content does.

It applies the same output logic as in the topic: Calling the functions with an URL.

LiveReload

There is no chance to trigger a LiveReload when the content of an URL changes. However, when a local JSON/CSV file changes, then a LiveReload will be triggered of course. Symlinks are not supported.

URLs and LiveReload: If you change any local file and the LiveReload is triggered, Hugo will either read the URL content from the cache or, if you have disabled the cache, Hugo will re-download the content. This can create huge traffic and you may also reach API limits quickly.

As downloading of content takes a while, Hugo stops processing your Markdown files until the content has been downloaded.

Examples

• Photo gallery JSON powered: https://github.com/pcdummy/hugo-lightslider-example
• GitHub Starred Repositories in a posts with the related short code.
• More? Please tell us!