Data modules

A .json.ts or .json.js file in content/ is a data module. bongo runs it and writes its default export as JSON, without the script extension. Use data modules for search indexes and other JSON files.

Paths

The default export

The default export is a value, or a function that returns one. The function receives $site, $pages, $section, $tags, $data, and $utils, as .hbs content does, and it may be async. $section holds the pages in the module's own folder. Type the function with Build.Data:

import type { Build } from 'bongo';

export default ({ $pages }: Build.Data) => $pages
	.filter(page => page.section === 'blog')
	.map(page => ({ title: page.title, path: page.path }));

Each page in $pages has its headings. A search index can list the sections of each page without a second read of the sources:

import type { Build } from 'bongo';

export default ({ $pages }: Build.Data) => $pages.map(page => ({
	title: page.title,
	path: page.path,
	sections: page.headings.filter(h => h.level === 2).map(h => ({ id: h.id, text: h.text })),
}));

bongo runs data modules once every page is known. See How a build works.

How it differs from a page

A data module is like an output file:

• It is not a page. It gets no layout, and it is not in $pages, $section, or $tags. bongo never minifies it or passes it to $hooks.transform. The JSON is always compact.
• It may import local files and packages, as the config does. It runs on every build, so it always reads the current pages.
• bongo dev serves it as application/json. It runs again after every change to a page, to the module, or to a local file that it imports.

Errors

The build fails, and the error names the file, when the module:

• has no default export,
• throws,
• returns something that JSON cannot hold, such as undefined.