如何通过 Golang 反射修改结构体的字段值_Golang Value 修改操作完整示例

func updateExportedFields(u *User) {
    v := reflect.ValueOf(u).Elem()

    // 修改 Name 字段
    nameField := v.FieldByName("Name")
    if nameField.IsValid() && nameField.CanSet() {
        nameField.SetString("Bob")
    }

    // 修改 Age 字段
    ageField := v.FieldByName("Age")
    if ageField.IsValid() && ageField.CanSet() {
        ageField.SetInt(30)
    }
}

type Profile struct {
    City string
}

type User struct {
    Name     string
    Age      int
    Profile  Profile
}

func updateNestedField(u *User) {
    v := reflect.ValueOf(u).Elem()
    profileField := v.FieldByName("Profile")
    if profileField.IsValid() {
        cityField := profileField.FieldByName("City")
        if cityField.CanSet() {
            cityField.SetString("Beijing")
        }
    }
}

func SetField(obj interface{}, fieldName string, value interface{}) error {
    v := reflect.ValueOf(obj)
    if v.Kind() != reflect.Ptr || v.IsNil() {
        return fmt.Errorf("obj must be a non-nil pointer")
    }

    v = v.Elem() // 解引用到结构体

    field := v.FieldByName(fieldName)
    if !field.IsValid() {
        return fmt.Errorf("field %s does not exist", fieldName)
    }

    if !field.CanSet() {
        return fmt.Errorf("field %s cannot be set", fieldName)
    }

    val := reflect.ValueOf(value)
    if !val.Type().AssignableTo(field.Type()) {
        return fmt.Errorf("cannot assign %T to %s", value, field.Type())
    }

    field.Set(val)
    return nil
}

u := &User{Name: "Alice", Age: 25}
SetField(u, "Name", "Charlie")
SetField(u, "Age", 35)