how to set a unique aws S3 file name? - angularjs

Question

I'm sending my file to an s3 bucket through the front end, as that seems more efficient from what i've read.
But, for some of my schemas / collections, I will not have the id for which the file / photo is associated -- as they are being created the same time as the upload:
$scope.add = function(){
if($scope.file.photo){
$scope.distiller.photo = 'http://s3.amazonaws.com/whiskey-upload/distillers/'
+ ' needs to be assigned to guid or collection id'
Distillery.create($scope.distiller).then(function(res){
console.log(res);
$scope.distillers.push(res.data.distiller);
var files = $scope.file;
var filename = files.photo.$ngfName;
var type = files.type;
var folder = 'distillers/';
var query = {
files: files,
folder: folder,
filename: res.data.distiller._id,
type: type
};
Uploads.awsUpload(query).then(function(){
$scope.distiller = {};
$scope.file = {};
});
});
}
else{
Distillery.create($scope.distiller).then(function(res){
toastr.success('distillery created without photo');
$scope.distiller = {};
});
}
};
The above code wouldn't work, unless I sent an update on the aws.Upload promise after the distillery object was created and after the file was uploaded to s3.
That doesn't seem efficient.
I could create a guid and assign that to the s3 file name, and also keep a reference of that on the distillery object. This seems hacky, though.
example Guid creator:
function guid() {
function s4() {
return Math.floor((1 + Math.random()) * 0x10000)
.toString(16)
.substring(1);
}
return s4() + s4() + '-' + s4() + '-' + s4() + '-' +
s4() + '-' + s4() + s4() + s4();
}
What would be the cleanest way to achieve what I want?

Answer 1

A good GUID generator is a very standard way to solve a unique id problem. Depending on the algorithm, the chance of a name collision could be close to nil. As you know, JavaScript does not have a native one, so one like yours is reasonable. I don't think its hacky at all.
Here is another by #briguy37:
function generateUUID() {
var d = new Date().getTime();
var uuid = 'xxxxxxxx-xxxx-4xxx-yxxx-xxxxxxxxxxxx'.replace(/[xy]/g, function(c) {
var r = (d + Math.random()*16)%16 | 0;
d = Math.floor(d/16);
return (c=='x' ? r : (r&0x3|0x8)).toString(16);
});
return uuid; };