使用Swift解码实时数据库响应

Question

我正在尝试解码Firebase实时数据库响应，但遇到解码错误，我认为这不是我的结构是问题所在，但我不知道我要去哪里做错了，我在做什么错？

现在的问题似乎是 promocodused 是字典而不是数组

ERROR HERE: typeMismatch(Swift.Array<Any>, Swift.DecodingError.Context(codingPath: [CodingKeys(stringValue: "usedBy", intValue: nil)], debugDescription: "Expected to decode Array<Any> but found a dictionary instead.", underlyingError: nil))

代码：

func getPromoCodeInfo(handler: @escaping (PromoCode?) -> ()) {
        guard let userid = AuthService.shared.userID else { return }
        promoCodes.queryOrdered(byChild: "owner").queryEqual(toValue: userid).observeSingleEvent(of: .value) { snapshot in
            
            
            for child in snapshot.children {
                guard let snap = child as? DataSnapshot else { return }
                guard let value = snap.value as? [String: Any] else { return }
                do {
                    let jsonData = try JSONSerialization.data(withJSONObject: value, options: [])
                    let decoded = try JSONDecoder().decode(PromoCode.self, from: jsonData)
                    handler(decoded)
                } catch {
                    print("ERROR HERE: \(error)")
                }
            }
        }
    }

datamodel

struct PromoCode: Codable {
    var active: Int
    var amount: Int?
    var code: String
    var percent: Int?
    var owner: Int?
    var usedBy: [PromoCodeUsed]?
}

struct PromoCodeUsed: Codable {
    var amount: Int
    var date: String
    var paid: Int
    var userid: Int
}

数据

{
  "active": 1,
  "code": "FELLA",
  "owner": 33206,
  "percent": 50,
  "usedBy": {
    "-N5lHtnKtAiBWrQMxW0a": {
      "amount": 1000,
      "date": "2022-06-29 21:08:51 +0000",
      "paid": false,
      "userid": 33206
    },
    "-N6L0vybeecuu175FV-4": {
      "amount": 5000,
      "date": "2022-07-07 00:20:41 +0000",
      "paid": false,
      "userid": 33206
    },
    "-N6L0w5WVS6mkVGrfJMW": {
      "amount": 5000,
      "date": "2022-07-07 00:20:41 +0000",
      "paid": false,
      "userid": 33206
    },
    "-N6L190TsMr6OJAXod1G": {
      "amount": 1000,
      "date": "2022-07-07 00:21:38 +0000",
      "paid": false,
      "userid": 33206
    }
  }
}

Answer 1

当您针对Firebase数据库执行查询时，可能会有多个结果。因此，快照包含这些结果的列表。即使只有一个结果，快照也将包含一个结果的列表。

您的代码需要处理此列表，但没有这样做。处理列表的最简单方法是您得到了，请循环过 snapshot.Children ，然后将每个单独的孩子快照转换为 promocode 对象。