使用 Swift Decodable 进行动态（但称为另一个键值）JSON 解码

Question

我查看了类似问题的答案，我无法很好地理解codingKey，此外它并不完全适用于我的情况，因为密钥并非完全“未知”，它是前一个密钥的值. 我的 API：

{
  "api": {
    "results": 1,
    "fixtures": [
      {
        "homeTeam": {
          "team_name": "Tottenham"
        },
        "awayTeam": {
          "team_name": "Everton"
        },
        "lineups": {
          "Tottenham": {
            "formation": "4-2-3-1"
          },
          "Everton": {
            "formation": "4-2-3-1"
          }
        }
      }
    ]
  }
}

我的代码：

class matchApiObject: Decodable
{
    let fixtures: [fixture]
    init (fixtures: [fixture])
    {
        self.fixtures = fixtures
    }
}

class fixture: Decodable
{
    let homeTeam: matchHomeTeamObject?
    let lineups: lineUpsObject?
    init (homeTeam: matchHomeTeamObject?, lineups: lineUpsObject?)
    {
        self.homeTeam = homeTeam
        self.lineups = lineups
    }
}

class matchHomeTeamObject: Decodable
{
    let team_name: String?
    init (team_name: String?)
    {
        self.team_name = team_name
    }
}

class lineUpsObject: Decodable
{
    struct homeLineUp: Decodable
    {
        let formation: String?
        init(formation: String?)
        {
            self.formation = formation
        }
    }
    struct awayLineUp: Decodable
    {
        let formation: String?
        init (formation: String?)
        {
            self.formation = formation
        }
    }
}

很明显，阵容对象的键不会是“homeLineUp”，而是按照 api 示例，即 homeTeam.team_name 的值。

所以我想象的解决方案是：

class lineUpsObject: Decodable
{
    struct homeTeam.team_name: Decodable
    {
        let formation: String?
        init(formation: String?)
        {
            self.formation = formation
        }
    }
    struct awayTeam.team_name: Decodable
    {
        let formation: String?
        init (formation: String?)
        {
            self.formation = formation
        }
    }
}

这是不可能的，我知道我必须为此使用编码键，但我不明白如何将键的名称声明为前一个键值的值 我不明白什么是 stringValue: String或 intValue: Int do in the codingkey answer do 或它们如何应用在这里，谢谢。

Answer 1

一个简单的解决方案是将lineups解码为字典，我将所有结构都以大写字母命名以符合命名约定。

不需要init 方法

struct Root : Decodable {
    let api : API
}

struct API : Decodable {
    let results : Int
    let fixtures : [Fixture]
}

struct Fixture : Decodable {
    let homeTeam, awayTeam: Team
    let lineups : [String:Lineup]
}

struct Team  : Decodable {
    let teamName : String
}

struct Lineup : Decodable {
    let formation : String
}

要将 snake_cased 键转换为 camelCased 结构成员，请添加适当的策略

let decoder = JSONDecoder()
decoder.keyDecodingStrategy = .convertFromSnakeCase

更复杂的解决方案是将formation 数据放入Team 结构，但这需要在Fixture 中实现init(from decoder:) 方法。