When I add a new record in a BBDD, I need in event OnAdd -> OnLoad assign user default that it is adding the new record as a record owner.

I created a user field (type Zoho CRM field user) but in my script I don't know how assign it. I try to write:

input.user =  zoho.loginuser;

But how they are different types I can't to asign it.

Can anyone help me?