How can I access variables within a Guzzle promise "then"?

I’m trying to make use of Guzzle to send two POST requests one after another (first to create a user, then to assign them a segment) and I seem to be struggling with accessing the variables I’ve defined throughout.

I’ve got the following in my function:

$data = [
    'email' => $email,
];

if (!empty($name)) {
    $data['fname'] = $name;
}

$request = $api->postAsync('v1/subscribers', [
    'auth' => [$account_data['api_key'], ''],
    'headers' => [
        'Content-Type' => 'application/json',
    ],
    'body' => json_encode([
        'first_name' => $data['fname'] ?? '',
        'email' => $data['email'],
    ]),
]);

$request->then(
    function (ResponseInterface $res) {
        $api->post('v1/subscribers/' . $data['email'] . '/segments', [
            'auth' => [$account_data['api_key'], ''],
            'headers' => [
                'Content-Type' => 'application/json',
            ],
            'body' => json_encode([
                'segment_ids' => [$list_id],
            ]),
        ]);
    }
);

$request->wait();

The variables $account_data and $api are defined higher up in my function and I’m able to access them when I created the initial promise using Guzzle (and it creates the user), but, when I try to use $api again inside of .then() it tells me that it is undefined.

How can I access $api (without global) / what am I missing here?

>Solution :

You cannot use variables defined outside of the anonymous function without either passing them as parameters, or by explicitly importing them with a use() statement. So your function would need to look something like:

$request->then(
    function (ResponseInterface $res) use ($api, $data, $account_data, $list_id) {
        $api->post('v1/subscribers/' . $data['email'] . '/segments', [
            'auth' => [$account_data['api_key'], ''],
            'headers' => [
                'Content-Type' => 'application/json',
            ],
            'body' => json_encode([
                'segment_ids' => [$list_id],
            ]),
        ]);
    }
);

See: Example #3 in the docs.