func ByField(from interface{}, to interface{}) error
ByField assigns the value of fields with "mapper" tag from one structs to
another struct. It looks for a field with name matching target key in the
source struct and assign the values if assignable to another.
func ByNameKey(from interface{}, to interface{}) error
ByField assigns the value of fields with "mapper" tag from one structs to
another struct. It matches the "name" key on both structs and assign the
values if assignable to another.