Swift 5 API JSON解码问题求助：结构体构造错误排查

嘿Ed，我一眼就看出问题出在哪了——你的结构体层级和JSON的键结构完全不匹配，这才导致了解码失败！

先看看你的JSON结构：

{
  "computer": {
    "location": {
      "username": "john.smith",
      "realname": "john smith",
      "real_name": "johnsmith",
      "email_address": "johnsmith@company.com",
      "position": "somePosition",
      "phone": "123-456-7890",
      "phone_number": "123-456-7890",
      "department": "",
      "building": "",
      "room": "someRoom01"
    }
  }
}

它的层级是：外层对象 → "computer"键 → "location"键 → 具体字段

但你写的结构体层级是：ComputerRecord → locationRecord → Location → record → Record，这和JSON的键完全对应不上，解码器自然找不到locationRecord这个键，所以抛出了keyNotFound错误。

修正后的结构体 #

你需要让结构体的层级和JSON的键一一对应，不需要多余的嵌套：

struct ComputerRecord: Codable {
    let computer: LocationContainer // 对应JSON里的"computer"键
}

struct LocationContainer: Codable {
    let location: UserInfo // 对应JSON里的"location"键
}

struct UserInfo: Codable {
    let username: String
    let realname: String
    let real_name: String
    let email_address: String
    let position: String
    let phone: String
    let phone_number: String
    let department: String
    let building: String
    let room: String
}

或者更简洁的嵌套写法（如果不需要单独拆分容器结构体的话）：

struct ComputerRecord: Codable {
    struct UserInfo: Codable {
        let username: String
        let realname: String
        let real_name: String
        let email_address: String
        let position: String
        let phone: String
        let phone_number: String
        let department: String
        let building: String
        let room: String
    }
    
    struct LocationContainer: Codable {
        let location: UserInfo
    }
    
    let computer: LocationContainer
}

修正后的解码代码 #

现在解码时的访问路径也要对应修正后的结构体：

do {
    let decoder = JSONDecoder()
    let computerRecord = try decoder.decode(ComputerRecord.self, from: data)
    if computerRecord.computer.location.username == nameToCheck {
        usernameSet(true, response, error)
    } else {
        print("In the else")
        usernameSet(false, response, error)
    }
} catch {
    print("解码错误详情：\(error)")
    usernameSet(false, response, error)
}

额外小提示 #

如果以后想把JSON里的蛇形命名（比如real_name）改成Swift风格的驼峰命名（realName），可以用CodingKeys做键映射：

struct UserInfo: Codable {
    let username: String
    let realname: String
    let realName: String // Swift风格属性名
    let emailAddress: String
    let position: String
    let phone: String
    let phoneNumber: String
    let department: String
    let building: String
    let room: String
    
    enum CodingKeys: String, CodingKey {
        case username, realname, position, phone, department, building, room
        case realName = "real_name"
        case emailAddress = "email_address"
        case phoneNumber = "phone_number"
    }
}

这样修改后，你的解码应该就能正常工作啦！

内容的提问来源于stack exchange，提问作者Edward S.