link-auth-with-mailchimp.md

Generating Links with Mailchimp that Log-in the Users Automatically

Learn how to generate links in Mailchimp that log in the users automatically.

How it works

You can basically just populate the wp_collectme_account_tokens table and add a merge tag with the token in Mailchimp. Then you'll be able to generate the links as described in the README.

However, it is more convenient to let the Mailchimpservice generate the merge tags. This way you can generate a different token for each mailing and thus also reuse the entries in the wp_collectme_account_tokens table, even for different causes.

The principle is simple. The Mailchimpservice generates the token with the following function: sha256sum( email || validUntilDate || secret ). The website can so validate the token without any additional information except for the shared secret and the validUntilDate. It then uses the email to retrieve the additional information from the wp_collectme_account_tokens table. If no entry matches the email, the token is considered invalid.

Configuring Mailchimp

Add a merge tag field for the CAUSE.

Configuring the Mailchimpservice

Add the following entry to your sync config /config/example.com.yml:

- crmKey: email1
  mailchimpKey: CAUSE # The merge tag for the cause
  type: token
  valid: '2022-12-31' # Token is valid until... Supported formats: https://www.php.net/manual/en/datetime.formats.php
  secret: v504CnK8BoNsznCSPWMiZtqLDu6oQOPh # any alphanumeric string
  sync: toMailchimp

Then perform a full sync.

Configuring the Website

Add the following filter:

add_filter( 'collectme_account_token', static function ( $token, $email ) {
    $email = strtolower(trim($email));
    $date = '2022-12-31';  // must match the config of the Mailchimpservice
    $secret = 'v504CnK8BoNsznCSPWMiZtqLDu6oQOPh'; // must match the config of the Mailchimpservice

    if (date_create($date) < date_create()) {
        // token expired
        return false;
    }

    $expectedToken = hash_hmac('sha256', $email . $date, $secret);

    if (!hash_equals($expectedToken, $token)) {
        return false;
    }

    try {
        return \Collectme\Model\Entities\AccountToken::getByEmail($email)->token;
    } catch (\Collectme\Exceptions\CollectmeDBException $e) {
        return false;
    }
}, 10, 2 );

Send the mailing

Add the link to your mailing:

<a href="https://example.com/post-with-collectme-shortcode?action=create&email=*|EMAIL|*&token=*|CAUSE|*">Log-in</a>

Where CAUSE in *|CAUSE|* must match your merge tag.