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/extras/highlighting | /extras/datafiles | Dynamic Content | 91 |
Dynamic content with a static site generator? Yes it is possible!
Besides the data files feature, we have also implemented the feature "Dynamic Content" which lets you load any JSON or CSV file from nearly any resource.
"Dynamic Content" consists at the moment of two functions getJson
and getCsv which are available in all template files.
Implementation details
Calling the functions with an URL
In any template file call the functions like:
{{ $dataJ := getJson "url" }}
{{ $dataC := getCsv "separator" "url" }}
or if you use a prefix or postfix for the URL the functions accepts 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 on the first position and can be
only one character long.
All passed arguments will be joined to the final URL, 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" }}
Eventually you can range over the array. This example will output the first 5 Github gists for a 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 on 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.
If you don't like caching at all you can fully disable to read from the
cache with the command line flag --ignoreCache. But hugo will always
write, on each build of the site, to the cache folder (silent backup).
Authentication when using REST URLs
At the moment you can only use those authentication methods which can be put into an URL. OAuth or other stuff is not implemented.
Loading local files
To load local files with the two functions getJson and getCsv the
source files must reside within Hugos working directory. The file
extension does not matter but the content.
It applies the same output logic as in the topic: Calling the functions with an URL.
Live reload
There is no chance to trigger a LiveReload when the content of an URL changes. But when a local JSON/CSV file changes then of course a live reload will be triggered. Symlinks not supported.
URLs and Live reload: If you change any local file and the live reload got trigger 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 creates a huge traffic and also you may reach API limits quickly.
As downloading of content takes a while Hugo stops with 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?
The Future
YAML and TOML
If the community demands the implementation of getYaml YAML or getToml TOML these functions will for sure follow.
getSql
The outlook to support more sources is of course implementing SQL support. The following description is an initial idea and may change.
Maybe adding a new CLI option:
--sqlSource=path/to/filename.ext
--sqlSource
The file must start with [mysql|postres|mssql|...]_[\w]+.ext
The part until the first underscore specifies the driver to use which can be one from https://github.com/golang/go/wiki/SQLDrivers.
The file itself contains only the connection string and no other comments or characters.
How the connection string looks like depends heavily on the used driver. For MySQL:
hugo --sqlSource=path/to/mysql_credentials.txt
The file mysql_credentials.txt contains the connection string:
username:password@protocol(address)/dbname?param=value and nothing more!
In your template you can process getSql the same way as with
the getJson function:
{{ $rows := getSql "SELECT id,artist,genre,title from musicTable" }}
<ul>
{{range first 5 $rows }}
<li>#{{ .id }} {{.artist}}</a></li>
{{end}}
</ul>
Queries with SELECT * from table are of course also possible.
Returned values will be converted to strings.