解析问题：APIError： keyNotFound key CodingKeys(stringValue： "data" ， intValue： nil)

Question

无法使用以下json 的可编码结构进行解析

{
"data": {
"listDeviceStateTable": {
"items": [
{
"Data": "{'state': -1, 'remainSec': 0}",
"PK": "DEVICE#144b584b-xxxx-xxxx-xxxx-1e584bdb1e8c",
"SK": "Station1"
},
{
"Data": "{'state': -1, 'remainSec': 0}",
"PK": "DEVICE#144b584b-xxxx-xxxx-xxxx-1e584bdb1e8c",
"SK": "Station2"
}
]
}
}
}

错误：

API错误：keyNotFound键编码键(字符串值："data"，intValue：nil(由：keyNotFound(CodingKeys(字符串值："data"，intValue：nil(，Swift。DecodingError.Context(codingPath:[]，debugDescription:"没有与键CodingKeys相关联的值(字符串值："data"；，intValue:nil(("data"(&"；，underlyingError:nil(((

型号：

//MARK: DeviceState 
struct DeviceState:Codable {
let data: DataClass
}
// MARK: - DataClass
struct DataClass: Codable {
let listDeviceStateTable: ListDeviceStateTable
}
// MARK: - ListDeviceStateTable
struct ListDeviceStateTable: Codable {
let items: [Item]
}
// MARK: - Item
struct Item: Codable {
let data, pk, sk: String
enum CodingKeys: String, CodingKey {
case data = "Data"
case pk = "PK"
case sk = "SK"
}
}

Answer 1

对我来说效果很好。这是我用来展示如何将json数据解码到结构中的测试代码。当然，根据您显示的json，Item->data在这里被解码为字符串。

struct ContentView: View {
@State var devState: DeviceState?

var body: some View {
Group {
if let devFirst = devState?.data.listDeviceStateTable.items.first {
Text("pk: (devFirst.pk)")
}
}
.onAppear {
let json = """
{
"data": {
"listDeviceStateTable": {
"items": [
{
"Data": "{'state': -1, 'remainSec': 0}",
"PK": "DEVICE#144b584b-xxxx-xxxx-xxxx-1e584bdb1e8c",
"SK": "Station1"
},
{
"Data": "{'state': -1, 'remainSec': 0}",
"PK": "DEVICE#144b584b-xxxx-xxxx-xxxx-1e584bdb1e8c",
"SK": "Station2"
}
]
}
}
}
"""
let data = json.data(using: .utf8)!
do {
devState = try JSONDecoder().decode(DeviceState.self, from: data)
print(devState)
} catch {
print("(error)")
}
}
}
}
struct DeviceState:Codable {
let data: DataClass
}
// MARK: - DataClass
struct DataClass: Codable {
let listDeviceStateTable: ListDeviceStateTable
}
// MARK: - ListDeviceStateTable
struct ListDeviceStateTable: Codable {
let items: [Item]
}
// MARK: - Item
struct Item: Codable {
let data, pk, sk: String

enum CodingKeys: String, CodingKey {
case data = "Data"
case pk = "PK"
case sk = "SK"
}
}

要将Data解码为String以外的内容，例如ItemData，您需要删除双引号，并将单引号替换为双引号(在值中，而不是键中(。例如"Data": "{'state': -1, 'remainSec': 0}",至"Data": {"state": -1, "remainSec": 0},并使用以下Item结构和解码代码：

// MARK: - Item
struct Item: Codable {
let data: ItemData
let pk, sk: String
enum CodingKeys: String, CodingKey {
case data = "Data"
case pk = "PK"
case sk = "SK"
}

init(from decoder: Decoder) throws {
let container = try decoder.container(keyedBy: CodingKeys.self)
pk = try container.decode(String.self, forKey: .pk)
sk = try container.decode(String.self, forKey: .sk)
do {
let theString = try container.decode(String.self, forKey: .data)
let json = theString.replacingOccurrences(of: """, with: "").replacingOccurrences(of: "'", with: """)
data = try JSONDecoder().decode(ItemData.self, from: json.data(using: .utf8)!)
} catch DecodingError.typeMismatch {
data = ItemData(state: 0, remainSec: 0) // <-- todo
}
}

}
struct ItemData: Codable {
let state, remainSec: Int
}

Answer 2

您需要多一个结构来解码像这样的Item中的数据

struct Item: Codable {
let data: ItemData
let pk, sk: String
enum CodingKeys: String, CodingKey {
case data = "Data"
case pk = "PK"
case sk = "SK"
}
}
struct ItemData: Codable {
let state, remainSec: Int
}