在Swift中使用不同的編碼鍵進行編碼/解碼

我必須從這個 JSON 中解碼一個物件：

{
  "id": "..."
  "someData": { ... },
  "elements": {
    "values": [
      {
        "id": "1",
        ...
      },
      {
        "id": "2"",
        ...
      }
    ]
  }
}

所以我有幾個這樣的結構：

struct Object: Codable {
  let id: String
  let someData: SomeCodableObject
  let elements: Elements
}

struct Elements: Codable {
  let values: [Value]
}

struct Value: Codable {
  let id: String
  ...
}

在用一些資料填充每個元素后，我必須發送一個類似于解碼的物件，但分別通過“elementQuotes”和“valueQuotes”更改“元素”和“值”（是的，我知道API應該避免這種奇怪的行為，但這是不可能的......），也就是像這樣的JSON：

{
  "id": "..."
  "someData": { ... },
  "elementQuotes": {
    "valueQuotes": [
      {
        "id": "1",
        ...
      },
      {
        "id": "2"",
        ...
      }
    ]
  }
}

有沒有辦法在不使用不同物件的情況下實作這一點（一些用于解碼，另一些用于編碼）。也就是說，有沒有辦法為編碼/解碼指定不同的編碼鍵字串值

我再說一遍：我知道這在 API 方面是一個非常糟糕的做法，但是......我必須管理這個“功能”

uj5u.com熱心網友回復：

你可以嘗試這樣的事情（我這里只處理解碼）：

extension String: Error {}

struct Object: Decodable {
  let id: String
  let elements: Elements

  enum CodingKeys: String, CodingKey {
    case id
    case elements
    case elementQuotes
  }

  init(from decoder: Decoder) throws {
    let container = try decoder.container(keyedBy: CodingKeys.self)
    self.id = try container.decode(String.self, forKey: .id)
    let elements = try container.decodeIfPresent(Elements.self, forKey: .elements)
    let elementQuotes = try container.decodeIfPresent(Elements.self, forKey: .elementQuotes)
    guard let realElements = elements ?? elementQuotes else { throw "Missing elements" }
    self.elements = realElements
  }

}

struct Elements: Decodable {
  let values: [Value]

  enum CodingKeys: String, CodingKey {
    case values
    case valueQuotes
  }

  init(from decoder: Decoder) throws {
    let container = try decoder.container(keyedBy: CodingKeys.self)
    let values = try container.decodeIfPresent([Value].self, forKey: .values)
    let valueQuotes = try container.decodeIfPresent([Value].self, forKey: .valueQuotes)
    self.values = values ?? valueQuotes ?? []
  }
}

struct Value: Decodable {
  let id: String
}

let test1 = """
{
  "id": "123",
  "elements": {
    "values": [
      {
        "id": "1"
      },
      {
        "id": "2"
      }
    ]
  }
}
""".data(using: .utf8)!

let test2 = """
{
  "id": "123",
  "elementQuotes": {
    "valueQuotes": [
      {
        "id": "1"
      },
      {
        "id": "2"
      }
    ]
  }
}
""".data(using: .utf8)!

let decoder = JSONDecoder()
let json1 = try decoder.decode(Object.self, from: test1)
let json2 = try decoder.decode(Object.self, from: test2)

uj5u.com熱心網友回復：

您可以嘗試撰寫自定義初始化解碼器

struct Root: Decodable {
  let id: String
  let someData: String
  let elements: Elements
    
    enum CodingKeys: String, CodingKey {
        case id, someData, elements
        case elementQuotes
    }
    
    init(from decoder: Decoder) throws {

        let container = try decoder.container(keyedBy: CodingKeys.self)
        id =  try container.decode(String.self, forKey: .id)
        someData = try container.decode(String.self, forKey: .someData)
        do {
            elements = try container.decode(Elements.self, forKey: .elements)
        }
        catch {
            elements =  try container.decode(Elements.self, forKey: .elementQuotes)
        }
    }
}

struct Elements: Decodable {
  let values: [Value]
    
    enum CodingKeys: String, CodingKey {
        case values
        case valuesQuotes
    }
    
    init(from decoder: Decoder) throws {
        let container = try decoder.container(keyedBy: CodingKeys.self)
        do {
            values = try container.decode([Value].self, forKey: .values)
        }
        catch {
            values =  try container.decode([Value].self, forKey: .valuesQuotes)
        }
    }
}

struct Value: Codable {
  let id: String
}

uj5u.com熱心網友回復：

對不同鍵進行編碼的一種簡單方法是添加自定義keyEncodingStrategy.

let encoder = JSONEncoder()
encoder.keyEncodingStrategy = .custom { keys in
    switch keys.last!.stringValue {
        case "elements": return AnyKey(stringValue: "elementQuotes")!
        case "values": return AnyKey(stringValue: "valueQuotes")!
        default: return keys.last!
            
    }
}

這還需要一個額外的結構AnyKey

struct AnyKey: CodingKey {
    var stringValue: String
    var intValue: Int?
    
    init?(stringValue: String) { self.stringValue = stringValue }
    init?(intValue: Int) {
        self.stringValue = String(intValue)
        self.intValue = intValue
    }
}

您可以在 switch 運算式中添加任意數量的案例

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