How do you change a filename once uploaded in Loopback?

I am trying to assign a profile picture to a user, I am currently trying to do this by uploading a file using the angular file-upload and then renaming it to the id of the user.

Is this

1. the best way to do this


2. if not how what is a better way

I just started looking at making a relation of a file belonging to one user but im not sure where the resources are to look for this

Any help appreciated!