Golang反射改善

Question

Anyone know a better way to do this? The goal is for a custom defined Field to be casted back again from a string to its int type.

switch val.Kind() {
    case reflect.Int:
            intID, err := strconv.ParseInt(id, 10, 0)
            if err != nil {
                    return err
            }
            val.Set(reflect.ValueOf(int(intID)))

    case reflect.Int8:
            intID, err := strconv.ParseInt(id, 10, 8)
            if err != nil {
                    return err
            }
            val.Set(reflect.ValueOf(int8(intID)))

    case reflect.Int16:
            intID, err := strconv.ParseInt(id, 10, 16)
            if err != nil {
                    return err
            }
            val.Set(reflect.ValueOf(int16(intID)))

    case reflect.Int32:
            intID, err := strconv.ParseInt(id, 10, 32)
            if err != nil {
                    return err
            }
            val.Set(reflect.ValueOf(int32(intID)))

    case reflect.Int64:
            intID, err := strconv.ParseInt(id, 10, 64)
            if err != nil {
                    return err
            }
            val.Set(reflect.ValueOf(intID))
   }

Answer 1

You can use Value.SetInt / Value.SetUint:

func setId(id string, v interface{}) {
    // error checking is left as an exercise
    val := reflect.ValueOf(v).Elem() // this will panic if v isn't a pointer
    switch val.Kind() {
    case reflect.Int, reflect.Int8, reflect.Int16, reflect.Int32, reflect.Int64:
        idn, _ := strconv.ParseInt(id, 10, 64)
        if val.OverflowInt(idn) {
            // handle large values
        }
        val.SetInt(idn)
    case reflect.Uint, reflect.Uint8, reflect.Uint16, reflect.Uint32, reflect.Uint64:
        idn, _ := strconv.ParseUint(id, 10, 64)
        if val.OverflowUint(idn) {
            // handle large values
        }
        val.SetUint(idn)
    }
}

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