如何在Sendinblue api v3中设置交易电子邮件属性？

So, I'm novice at best with php, but I've figured out how to set up and send transactional emails with sendinblue.

But for whatever reason, I can't seem to set the attributes.

This is really the only line of the code that I can't seem to get to work.

$sendEmail['attributes'] = array('FIRSTNAME' => "STEVE");$sendEmail['attributes'] = array('FIRSTNAME' => "STEVE"); I've also tried

$sendEmail['params'] = array('FIRSTNAME' => "STEVE");

and

$params['attributes'] = array('FIRSTNAME' => "STEVE");

...and probably 127 variations of the above, but I can't seem to get it it to work.

I also can't seem to figure out how to create a contact with php...

What is the "create contact" equivilent of this line of code:

$sendEmail = new \SendinBlue\Client\Model\SendEmail();

?

Like I said, my emails asre sending, but where I expect them to read "Dear STEVE," they read "Dear ,"

BELOW IS THE FULL CODE:

<?php


# Include the SendinBlue library\
require_once('../vendor/autoload.php');

# Instantiate the client\

$config = SendinBlue\Client\Configuration::getDefaultConfiguration()->setApiKey('api-key', 'MY API KEY HERE');
// Uncomment below to setup prefix (e.g. Bearer) for API key, if needed
// $config = SendinBlue\Client\Configuration::getDefaultConfiguration()->setApiKeyPrefix('api-key', 'Bearer');
// Configure API key authorization: partner-key
$config = SendinBlue\Client\Configuration::getDefaultConfiguration()->setApiKey('partner-key', 'MY API KEY HERE');
// Uncomment below to setup prefix (e.g. Bearer) for API key, if needed
// $config = SendinBlue\Client\Configuration::getDefaultConfiguration()->setApiKeyPrefix('partner-key', 'Bearer');

$apiInstance = new SendinBlue\Client\Api\SMTPApi(
    // If you want use custom http client, pass your client which implements `GuzzleHttp\ClientInterface`.
    // This is optional, `GuzzleHttp\Client` will be used as default.
    new GuzzleHttp\Client(),
    $config
);


$templateId = 2; // int | Id of the template

$sendEmail = new \SendinBlue\Client\Model\SendEmail(); // \SendinBlue\Client\Model\SendEmail | 

 $sendEmail['emailTo'] = array("test@example.com");

$params['attributes'] = array('FIRSTNAME' => "STEVE"); //THIS IS THE LINE OF CODE THAT ISN'T WORKING.


//$mail->setFrom('info@myeasy.wedding', 'My Easy Wedding');



try {
    $result = $apiInstance->sendTemplate($templateId, $sendEmail);
    print_r($result);
} catch (Exception $e) {
    echo 'Exception when calling SMTPApi->sendTemplate: ', $e->getMessage(), PHP_EOL;
}

?>