如何使用 Swift Decodable 从一组 UUID 键映射关系？

Question

我有一个结构，其中：

Factories 有很多 Cards;

而且，players可以有多个Cards（未实现）；他们是同一张牌。

用于测试和内部完整性检查；我想暂时将卡片数组放在自己的 JSON 数组中。

所以我想出的结构是这样的：

// Example JSON
{
    "factories": [
        {
            "id": "7a24a713-c0aa-4498-....",
            "name": "Steel Factory",
            "cost": 4,
            "references": [
                { "id": "e936b897-c203-44a5-9cf0-27720f655b68" },
                { "id": "da35424a-6546-4c72-a51c-1f6abfd601a3" }
            ],
     ...
     "cards": [
          { "id": "e936b897-c203-44a5-9cf0-27720f655b68", name: "Card #1", cost: 4 }
          { "id": "da35424a-6546-4c72-a51c-1f6abfd601a3", name: "Card #2", cost: 4 }
     ] 
...
}

备注

The Factory JSON structure has no cards; its considered to be an empty array when decoding

用例：

Fill the factories cards array (empty at init) with the contents of the references based off the matching UUID keys <

Swift 结构是：

struct Factory: Codable, Identifiable, Equatable, Hashable {
    let id: UUID
    let name: String
    let cost: Int
    var cards: [Card]? 
    internal var references: [Reference]?

    private enum CodingKeys: String, CodingKey {
        case id, name, cost, references
    }
}

struct Reference: Codable, Identifiable, Hashable, Equatable {
    var id: UUID

    private enum CodingKeys: String, CodingKey {
        case id
    }
}

struct Card: Codable, Identifiable, Hashable, Equatable {
    var id: UUID 
    var name: String
    var cost: Int

    private enum CodingKeys: String, CodingKey {
        case id, name, cost
    }
}

所以，尝试这样做；我已经为每个结构写出自定义 initWithCoder。

extension Reference {
    init(from decoder: Decoder) throws {
        let container = try decoder.container(keyedBy: CodingKeys.self)
        id = try container.decode(UUID.self, forKey: .id)
    }
}


extension Factory {

    init(from decoder: Decoder) throws {
        let container = try decoder.container(keyedBy: CodingKeys.self)

        id = try container.decode(UUID.self, forKey: .id)
        name = try container.decode(String.self, forKey: .name)
        cost = try container.decode(Int.self, forKey: .cost)
        cards = try container.decodeIfPresent([Card].self, forKey: .cards) ?? [Card]()
        references = try container.decode([Reference].self, forKey: .references)
    }
}

extension Card {
   init(from decoder: Decoder) throws {
       let container = try decoder.container(keyedBy: CodingKeys.self)

       id = try container.decode(UUID.self, forKey: .id)
       name = try container.decode(String.self, forKey: .name)
       cost = try container.decode(String.self, forKey: .cost)

   }
}

我想做这样的事情：

// Factory decoder 
references = try container.decode([Reference].self, forKey: .references)

// Find all cards that match the reference ID
// add the matched cards to this factories cards array
let matchedCards: [Card]? = references.map { [=14=]  }
print ("matchedCards")

但考虑到无法通过此结构直接访问 Card 结构，我不确定将 $0 映射到什么。

我知道我可以将卡片作为子数组放在工厂结构中。

但我正在考虑，将来可能会出现一个桥接结构，其中包含关键引用，例如 one to many through JSON 结构。

我感谢提供的任何反馈。

Answer 1

let referenceIds:[String] = references.map { [=10=].id }

let decodedCards = container.decode([Card].self, forKey: .cards)

let matchedCards[Card] = decodedCards.filter(where: { referenceIds.contains([=10=].id)})

self.cards = matchedCards // factory.cards

如何使用 Swift Decodable 从一组 UUID 键映射关系？

How to use Swift Decodable to map relationships from an array of UUID keys?

arrays

json

swift

relationship

decodable