Golang如何使用reflect修改嵌套结构体字段_Golang reflect嵌套字段修改方法

func setNestedField(obj interface{}, fieldPath []string, value interface{}) error {
    v := reflect.ValueOf(obj)
    if v.Kind() != reflect.Ptr || !v.Elem().IsValid() {
        return fmt.Errorf("obj must be a valid pointer")
    }
    v = v.Elem() // 解引用指针

    for i, name := range fieldPath {
        if v.Kind() == reflect.Struct {
            v = v.FieldByName(name)
            if !v.IsValid() {
                return fmt.Errorf("field %s not found", name)
            }
        } else if v.Kind() == reflect.Ptr && v.Elem().Kind() == reflect.Struct {
            v = v.Elem().FieldByName(name)
            if !v.IsValid() {
                return fmt.Errorf("field %s not found after dereferencing", name)
            }
        } else {
            return fmt.Errorf("unexpected type at %s", strings.Join(fieldPath[:i+1], "."))
        }

        // 如果不是最后一层，继续深入
        if i < len(fieldPath)-1 && (v.Kind() == reflect.Ptr || v.Kind() == reflect.Interface) {
            v = v.Elem()
        }
    }

    if !v.CanSet() {
        return fmt.Errorf("field cannot be set")
    }

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

    v.Set(newValue)
    return nil
}

type Address struct {
    City string
}
type Person struct {
    Name    string
    Addr    Address
    AddrPtr *Address
}

p := Person{}
err := setNestedField(&p, []string{"Addr", "City"}, "Beijing")
if err != nil {
    log.Fatal(err)
}
fmt.Println(p.Addr.City) // 输出: Beijing

// 对指针嵌套字段
err = setNestedField(&p, []string{"AddrPtr", "City"}, "Shanghai")
if err != nil {
    log.Fatal(err)
}
fmt.Println(p.AddrPtr.City) // 输出: Shanghai

if v.Kind() == reflect.Ptr && v.IsNil() {
    elemType := v.Type().Elem()
    newPtr := reflect.New(elemType) // 创建新实例
    v.Set(newPtr)                   // 设置到原字段
    v = newPtr.Elem()               // 继续进入结构体
}