golang动态类型转换

Question

From a snippet (not comprehensively functional here):

type SomeType struct {
    UserEmail   sql.NullString    `db:"user_email"`
    RecID       sql.NullInt64     `db:"rec_id"`
}

for g := 0; g < s.NumField(); g++ {
   f := s.Field(g)
   tType = f.Type().String()

   tType = strings.Replace(tType, `sql.Null`, ``, 1)
   tType = strings.Replace(tType, `mysql.Null`, ``, 1)
   tType = strings.Replace(tType, `decimal.NullDecimal`, `Decimal`, 1)
   tType = strings.Replace(tType, `myTime`, `Time`, 1)

   fmt.Println(g, typeOfT.Field(g).Name, tType, f)
}

For normal output, I write UserEmail.String. If the .String is absent, then the output is:

   UserEmail String {[e-mail] true}

How would I dynamically append the .String, or .Int64, depending on the data type, wherein that type extention actually functions to produce:

   UserEmail String [e-mail]

Essentially turning the strings "UserEmail" and "String" into UserEmail.String

Thanks!