Using element API to query a matrix field

Question

I'm using the Element API to grab entries and their data (via this answer). What I want to do is accept a URL parameter (eg. ?location=foo) and filter the returned entries by a Matrix field called fundingProgramme, where its sub-field area (a dropdown) has a value matching the URL query parameter.

I can't work out how to do this using the Element API. Here's what I've got:

'content/<locale:en|cy>/programs.json' => function($locale) {

    $siteId = ($locale === 'en' || !$locale) ? 1 : 2;

    return [
        'elementType' => Entry::class,
        'criteria' => [
            'section' => 'fundingProgrammes',
            'siteId' => $siteId
        ],
        'transformer' => function(Entry $entry) {
            $request = Craft::$app->getRequest();
            $location = $request->getParam('location');
            return [
                'title' => $entry->title,
                'test' => $entry->fundingProgramme[0]->area->label
            ];
        },
    ];

(the test key at the end is me proving that I can retrieve the field programmeTitle from the Matrix field fundingProgramme. There's only one stored against each entry, though).

How can I query against this field? Would I have to do this in the transformer rather than the criteria?

Using element API to query a matrix field

0 Answers0