Basename parsers

When Lume is scanning the source folder, it can automatically extract some info from the basename of files (the filename after removing the extension) and folders.

For example, let's say you want to create the variable order to sort pages in a menu. A way to make this variable explicit is to save your pages with the [order]. prefix:

.
├── 1.welcome.md
├── 2.introduction.md
├── 3.the-basics.md
└── 4.advanced.md

One of the advantages of making this variable explicit in the filesystem is that you can see the source files sorted the same way in your editor as well as on the final site.

In Lume, the filename is used by default to generate the final URLs (more info), so the page files above generates the following URLs:

/1.welcome/
/2.introduction/
/3.the-basics/
/4.advanced/

That could work, but what we really want is to remove the order prefix and store it in the page data. To do that, we can register a basename parser using the function site.parseBasename in our _config.ts file:

site.parseBasename((basename) => {
  // Regexp to detect the order pattern
  const match = basename.match(/(\d+)\.(.+)/);

  if (match) {
    const [, order, basename] = match;

    // Return the order value and the new basename without the prefix
    return {
      order: parseInt(order),
      basename,
    };
  }
});

As you can see, the function is simple: it receives the basename and, if the basename matches the regular expression, it return an object with the parsed values. Note that the returned object contains the basename key with the original basename but without the prefix, that will be used to generate the final URL.

If the basename doesn't match the regular expression, it doesn't return anything, so nothing will be changed.

The parseBasename function is used for both files and folders. This allows extracting values from a folder name and storing them as shared data, so they are available to all pages inside.

Extract dates

Lume, by default, is configured with a basename parser to extract dates from filenames. See page dates for more info.