Golang处理JSON序列化错误技巧

func SafeMarshal(v interface{}, context string) ([]byte, error) {
    data, err := json.Marshal(v)
    if err != nil {
        // 记录带上下文的错误，避免只记“marshal failed”
        log.Printf("[JSON Marshal Error] Context: %s, Value: %+v, Err: %v", 
            context, 
            redactSensitive(v), // 自定义脱敏函数，避免打印密码/token
            err)
        return nil, fmt.Errorf("json marshal failed in %s: %w", context, err)
    }
    return data, nil
}

decoder := json.NewDecoder(r)
decoder.DisallowUnknownFields() // 遇到JSON中存在结构体没有的字段时立即报错

var user User
if err := decoder.Decode(&user); err != nil {
    log.Printf("Decode failed for user data: %v, raw input: %s", 
        err, string(dumpRawInput(r))) // 可临时读取并截断原始字节流
    return err
}

func (u *User) UnmarshalJSON(data []byte) error {
    type Alias User // 防止无限递归
    aux := &struct {
        Name *string `json:"name"`
        Age  *int    `json:"age"`
        *Alias
    }{
        Alias: (*Alias)(u),
    }
    if err := json.Unmarshal(data, &aux); err != nil {
        return err
    }
    if aux.Name != nil && *aux.Name == "" {
        return errors.New("field 'name' cannot be empty")
    }
    if aux.Age != nil && (*aux.Age < 0 || *aux.Age > 150) {
        return errors.New("field 'age' out of valid range [0,150]")
    }
    return nil
}

func ValidateUserInput(u User) error {
    if u.Name == "" {
        return fmt.Errorf("validation failed: User.Name is empty")
    }
    if u.Age < 0 {
        return fmt.Errorf("validation failed: User.Age = %d < 0", u.Age)
    }
    if u.Profile == nil {
        return fmt.Errorf("validation failed: User.Profile is nil")
    }
    if u.Profile.Address == nil {
        return fmt.Errorf("validation failed: User.Profile.Address is nil")
    }
    return nil
}