The magnetic part of my macbook pro charger broke off? how do i fix it?!?!?

the charger still works but when i take it out the the charger part attached to the wire just has the metal prongs sticking out and not the metal piece that protects them and makes it magnetic to the computer. its just annoying it came apart because the charger comes out of my computer really easily know so if anyone knows how to fix it that would e great!