Twilio & NodeJS: can't find and delete Media instances/resources - arrays

Question

I'm using Twilio's NodeJS module & API to send out MMS messages with images attached (from a remote URL), and I want to delete the Media instances that get created on Twilio servers as soon as I send out the messages.
My messages send out correctly, and in the callback, I'm trying to 1) list media instances for the current message, then 2) loop through those instances and delete. The problem is that the mediaList array that comes back from the API for a current message is always empty.
Here's my code:
twilio_client.messages.create({
body: "Thanks for taking a photo. Here it is!",
to: req.query.From,
from: TWILIO_SHORTCODE,
mediaUrl: photo_URL,
statusCallback: STATUS_CALLBACK_URL
}, function(error, message) {
if (!error) {
twilio_client.messages(message.sid).media.list(function(err, data) {
console.log(data);
// The correct object comes back as 'data' here per the API
// but the mediaList array is empty
}
console.log('Message sent via Twilio.');
res.status(200).send('');
} else {
console.log('Could not send message via Twilio: ');
console.log(error);
res.status(500).send('');
}
});

Answer 1

So, it turns out that trying to get the media list at the point I was trying to doesn't work because the media instances didn't exist yet.
I have a separate little app running at the statusCallback (I supply a URL via a constant in the code above, STATUS_CALLBACK_URL), that until now, just checked to see if a message I tried to MMS to a user wasn't handled properly by Twilio, and alerted the user to a problem via SMS. So, I added a check in that same app to see if the message was actually 'sent' to the user, and then checked for and deleted the media instance(s) associated with the message at that point, and it works fine. Here's my code:
// issue message to user if there's a problem with Twilio getting the photo
if (req.body.SmsStatus === 'undelivered' || req.body.SmsStatus === 'failed') {
twilio_client.messages.create({
body: "We're sorry, but we couldn't process your photo. Please try again.",
to: req.body.To,
from: TWILIO_SHORTCODE
}, function(error, message) {
if (!error) {
console.log('Processing error message sent via Twilio.');
res.send(200,'');
} else {
console.log('Could not send processing error message via Twilio: ' + error);
res.send(500);
}
});
}
// delete media instance from Twilio servers
if (req.body.SmsStatus === 'sent') {
twilio_client.messages(req.body.MessageSid).media.list(function(err, data) {
if (data.media_list.length > 0) {
data.media_list.forEach(function(mediaElement) {
twilio_client.media(mediaElement.sid).delete;
console.log("Twilio media instance deleted");
});
}
});
}