Empty mail_settings returns empty JSON array instead of object

[Dreyer]

Issue Summary

When assigning empty mail settings, JSON serialization returns an empty array but the API expects an object (or null, also works).

// for purpose of illustration, user has set this to false.
$spam_check = false;

$from = new Email(null, "test@example.com");
$subject = "Hello World from the SendGrid PHP Library";
$to = new Email(null, "test@example.com");
$content = new Content("text/plain", "some text here");
$mail = new Mail($from, $subject, $to, $content);
$to = new Email(null, "test2@example.com");
$mail->personalization[0]->addTo($to);

$mail_settings = new \SendGrid\MailSettings();
// not adding any settings because spam check is false.
if ($spam_check) {
            $spam_check = new \SendGrid\SpamCheck();
            $spam_check->setEnable(true);
            $spam_check->setThreshold(1);
            $spam_check->setPostToUrl('https://spamcatcher.sendgrid.com');
            $mail_settings->setSpamCheck($spam_check);
}
$mail->setMailSettings($mail_settings);
$apiKey = getenv('SENDGRID_API_KEY');
$sg = new \SendGrid($apiKey);

$response = $sg->client->mail()->send()->post($mail);
echo $response->statusCode();
echo $response->body();
echo $response->headers();

Seems to be resolved by altering MailSettings::jsonSerialize() on L:569

   public function jsonSerialize()
    {
        return array_filter(
            [
                'bcc' => $this->getBccSettings(),
                'bypass_list_management' => $this->getBypassListManagement(),
                'footer' => $this->getFooter(),
                'sandbox_mode' => $this->getSandboxMode(),
                'spam_check' => $this->getSpamCheck()
            ],
            function ($value) {
                return $value !== null;
            }
        ) ?: null;
    }

Steps to Reproduce

1. Don't add any mail settings.
2. Attempt to send request.
3. Get error message:

{"errors":[{"message":"Invalid type. Expected: object, given: array.","field":"mail_settings","help":"http://sendgrid.com/docs/API_Reference/Web_API_v3/Mail/errors.html#-Mail-Settings-Errors"}]}

I would imagine it possible to instantiate new SendGrid\MailSettings(); and then optionally add settings as flags are required at run time or by users options for a possible spam check.

Technical details:

• sendgrid-php Version: master (latest commit: 46f85e6)
• PHP Version: 5.6.2

[thinkingserious]

Thanks for reporting this bug @Dreyer, especially in such detail :)

I have added this to our backlog for a fix.

It can gain priority with other +1s and/or a PR.

[Skrath]

Additionally, if you set Sandbox Mode to false explicitly:

$mail = new \SendGrid\Mail();
$mail_settings = new \SendGrid\MailSettings();
$sandbox_mode = new \SendGrid\SandBoxMode();
$sandbox_mode->setEnable(false);
$mail_settings->setSandboxMode($sandbox_mode);
$mail->setMailSettings($mail_settings);

You get a very similar error: "message":"Invalid type. Expected: object, given: array.","field":"mail_settings.sandbox_mode"

Setting Sandbox Mode to true works as expected.

[thinkingserious]

Thanks for the confirmation @Skrath! I've added your vote to this issue in our backlog.