[英]How to use Swift Decodable to map relationships from an array of UUID keys?
我有一个结构,其中:
Factories
有很多Cards
;
而且, players
可以拥有许多Cards
(未实施); 他们是同一张牌。
用于测试和内部完整性检查; 我想暂时将卡片阵列单独保存在其自己的 JSON 阵列中。
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 }
]
...
}
笔记
工厂JSON结构无
cards
; 解码时它被认为是一个空数组
用例:
根据匹配的 UUID 键,用引用的内容填充工厂卡数组(初始化时为空)<
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
}
}
因此,尝试这样做; 我已经为每个结构编写了自定义的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 { $0 }
print ("matchedCards")
但是我不确定 map $0 考虑到 Card 结构不能通过这个结构直接访问。
我知道我可以将卡片作为子数组放在工厂结构内。
但我在想,将来可能会有一个时间,我需要一个桥接结构,其中包含关键引用,例如one to many through
JSON 结构的一对多。
我感谢提供的任何反馈。
let referenceIds:[String] = references.map { $0.id }
let decodedCards = container.decode([Card].self, forKey: .cards)
let matchedCards[Card] = decodedCards.filter(where: { referenceIds.contains($0.id)})
self.cards = matchedCards // factory.cards
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