打开使用PHP版SendGrid邮件发送的电子邮件附件时，我收到了损坏的文件

I am trying to send attachments with SendGrid through PHP, but keep getting a corrupted file error when I open the attachment. The error message "We're sorry. We can't open 'file.docx' because we found a problem with its contents" and when I click on the details of the error I see "The file is corrupt and cannot be opened"

My code looks like the below:

$sendGridLoginInfo = $contactViaEmail->getSendGridLoginInfo();    
        $sendgrid = new SendGrid($sendGridLoginInfo['Username'], $sendGridLoginInfo['Password']);    
        $mail = new SendGrid\Mail();
        //Add the tracker args
        $mail->addUniqueArgument("EmailID", $emailID);
        $mail->addUniqueArgument("EmailGroupID", $emailGroupID);
        /*
        *    INSERT THE SUBSITUTIONS FOR SEND GRID
        */
        foreach ($availableSubstitutions as $availableSubstitution)
        {
            $mail->addSubstitution("[[" . $availableSubstitution . "]]", $substitutions[$availableSubstitution]);
        }

        /*
        *    ADD EACH EMAIL AS A NEW ADD TO
        *    This makes it BCC (because each person gets their own copy) and each person gets their own individualized email.
        */
        foreach ($emailInfo['SendToEmailAddress'] as $toEmail)
        {


            if ($sendToLoggedInUser)
            {
                $mail->addTo($adminEmailAddress);
            }
            else
            {
                $mail->addTo($toEmail);
            }
            $trashCount++;
        }

        //Set the subject
        $mail->setSubject($emailInfo['EmailSubject']);

        //Instantiate the HTML Purifier (for removing the html)
        $config = HTMLPurifier_Config::createDefault();
        $config->set('HTML', 'Allowed', '');
        $purifier = new HTMLPurifier($config);
        $mail->setText($purifier->purify($emailBody));
        $mail->setHtml($emailBody);

        if ($emailInfo['AttachmentID'])
        {
            $sql = "SELECT
                        AttachmentPath
                    FROM
                        EmailAttachments
                    WHERE
                        EmailAttachments.AttachmentID = :attachmentID";    
            if ($query = $pdoLink->prepare($sql))
            {
                $bindValues = array();
                $bindValues[":attachmentID"] = $emailInfo['AttachmentID'];

                if ($query->execute($bindValues))
                {
                    if ($row = $query->fetch(\PDO::FETCH_ASSOC))
                    {
                        $attachment = "";
                        $mail->addAttachment($sitedb . $row['AttachmentPath']);
                    }
                }
            }                
        }




        if ($sendToLoggedInUser)
        {
            $mail->setFrom($adminEmailAddress);
            $mail->setReplyTo($adminEmailAddress);
        }
        else
        {
            $mail->setFrom($emailInfo['FromAddress']);
            $mail->setReplyTo($emailInfo['ReplyTo']);
        }            
        $mail->setFromName($emailInfo['FromName']);

        $sendgrid->web->send($mail);

I've played with the content type and everything else that I can think of and just cannot find out what is causing the attachments to be corrupted.

You need to create an attachment object to add an attachment, you can't use the path directly like you are. SendGrid requires files to be sent as base64 encoded strings.

You'll need to create the attachment object, you could do this as a method:

public function getAttachment($path) 
{
    if (!file_exists($path)) {
        return false;
    }

    $attachment = new SendGrid\Attachment;
    $attachment->setContent(base64_encode(file_get_contents($path))); 
    $attachment->setType(mime_content_type($path));
    $attachment->setFilename(basename($path));
    $attachment->setDisposition('attachment');
    return $attachment;
}

Then add it to your email:

$attachment = $this->getAttachment($sitedb . $row['AttachmentPath']);
if ($attachment instanceof SendGrid\Attachment) {
    $mail->addAttachment($attachment);
}