php-sdk 3.0.0-alpha: How to get contact Id (how to unsubscribe contact from specific list by email)?

[FilipQL]

I am using php-sdk 3.0.0-alpha (because I need Guzzle 6 for the other packages/dependencies, as stated here: #113). There is method unsubscribeContact which requires $contactId (int - Unique contact id):

    /**
     * Opt out a contact
     * @param string $accessToken - Constant Contact OAuth2 access token
     * @param int $contactId - Unique contact id
     * @return boolean
     * @throws CtctException
     */
    public function unsubscribeContact($accessToken, $contactId) {
        $baseUrl = Config::get('endpoints.base_url') . sprintf(Config::get('endpoints.contact'), $contactId);

        try {
            $response = parent::sendRequestWithoutBody($accessToken, 'DELETE', $baseUrl);
        } catch (TransferException $e) {
            throw parent::convertException($e);
        }

        return ($response->getStatusCode() == 204) ? true : false;
    }

But how to get that Id? For example, if I want to unsubscribe example@example.com from specific list - how can I get the id of that contact? There is no method to get contact by email address. Also, the unsubscribeContact method doesn't receive any param to determine the list.

[FilipQL]

OK, I found how: $contact->results[0]->id (and $contact = $this->cc->contactService->getContacts($this->token, ["email" => Input::get('email')]);. This (->results[0]->id) is not very intuitive, and I did not find this in the documentation/examples.