Search function for multi-language sites

This is what I learned from user FabianSperrle:

foreach ($page->children()->filterBy('languages', $site->language()->code(), ',') as $child) {

Source: Filter child pages by available translations

Where do I find out what can be filtered by filterBy function? The example above is not mentioned in the docs.
Is this a working example? Sadly, it does not work for me when applying the filterBy function to foreach function.

I also tried to filter after index()

$results = $site->index()->filterBy('languages', $site->language()->code(), ',')->visible()->search($query, 'title|text');

but did not succeed.

EDIT: I now understand that this example of FabianSerrle only works when adding custom fields to the text files.
Is there any other way to filter by language? This should be a basic function of a CMS, I guess.

1 Like