Updating a member's group interests using MailChimp API V3

Question

I am running the following code (I've hidden ID's) to add/update a subscriber's interest groups in a MailChimp list:

$mailchimp->patch('lists/1234567/members/' . md5('[email protected]'), [
    'status' => 'subscribed',
    'merge_fields' => array(
        'FNAME' => 'Ben',
        'LNAME' => 'Sinclair',
    ),
    'interests' => array(
        'abcd1234' => true,
        'defg6789' => true,
    ),
]);

The interests key is what I'm having issues with.

I presumed whatever you put in this key will overwrite what currently exists.

It doesn't seem to be the case. It only adds new interests but does not remove any if the ID's are not in the array. I am not getting any errors.

Does anyone know how to overwrite interest groups? Or if that's not possible, is there a way to remove interest groups?

Answer 1

For completion I wanted to add this answer so people stumbling upon this post can find a quick solution.

$mailchimp->patch('lists/1234567/members/' . md5('[email protected]'), [
    'status' => 'subscribed',
    'merge_fields' => array(
        'FNAME' => 'Ben',
        'LNAME' => 'Sinclair',
    ),
    'interests' => array(
        'abcd1234' => true, // Attached
        'defg6789' => false, // Detached
    )
]);

In this example the interest 'abcd1234' will be attached and the interest 'defg6789' will be detached.

Other interests that are not listed will remain on their original value.