正在从 Web API 解析 Json
Parsing Json from Web API
你好,我叫 Nico,
我是 App 的完全初学者 programming/SwiftUI。
我正在尝试从网络 api 解析 json 数据,但不知何故我无法正确解析数据。我假设我的 json 结构不正确,但我找不到问题所在。
我从网上得到的 Json API 看起来像这样:
{
"pois": [
{
"id": "2635094451",
"lat": "52.410150",
"lat_s": "52.4",
"lng": "10.776630",
"lng_s": "10.8",
"street": "Röntgenstraße",
"content": "8137285512",
"backend": "0-239283152",
"type": "1",
"vmax": "50",
"counter": "0",
"create_date": "2021-11-18 13:21:50",
"confirm_date": "2021-11-18 13:21:43",
"gps_status": "-",
"info": " {\"qltyCountryRoad\":1,\"confirmed\":\"0\",\"gesperrt\":\"0\",\"precheck\":\"[Q1|21|0]\"}",
"polyline": ""
}
],
"grid": []
}
我的结构如下所示:
struct APIResponse: Codable {
let pois: [InputDataPois]
let grid: [InputDataGrid]
private enum CodingKeys: String, CodingKey {
case pois
case grid
}
init(from decoder: Decoder) throws {
let container = try decoder.container(keyedBy: CodingKeys.self)
self.pois = try container.decode(APIResponse.self, forKey: .pois).pois
self.grid = try container.decode(APIResponse.self, forKey: .grid).grid
}
}
struct InputDataPois: Codable, Identifiable {
let id:String
let lat:String
let lat_s:String
let lng:String
let lng_s:String
let street:String
let content:String
let backend:String
let type:String
let vmax:String
let counter:String
let create_date:String
let confirm_date:String
let gps_status:String
let info:String
let polyline:String
}
extension InputDataPois {
private enum CodingKeys: String, CodingKey {
case id
case lat
case lat_s
case lng
case lng_s
case street
case content
case backend
case type
case vmax
case counter
case create_date
case confirm_date
case gps_status
case info
case polyline
}
init(from decoder: Decoder) throws {
let container = try decoder.container(keyedBy: CodingKeys.self)
self.id = try container.decode(String.self, forKey: .id)
self.lat = try container.decode(String.self, forKey: .lat)
self.lat_s = try container.decode(String.self, forKey: .lat_s)
self.lng = try container.decode(String.self, forKey: .lng)
self.lng_s = try container.decode(String.self, forKey: .lng_s)
self.street = try container.decode(String.self, forKey: .street)
self.content = try container.decode(String.self, forKey: .content)
self.backend = try container.decode(String.self, forKey: .backend)
self.type = try container.decode(String.self, forKey: .type)
self.vmax = try container.decode(String.self, forKey: .vmax)
self.counter = try container.decode(String.self, forKey: .counter)
self.create_date = try container.decode(String.self, forKey: .create_date)
self.confirm_date = try container.decode(String.self, forKey: .confirm_date)
self.gps_status = try container.decode(String.self, forKey: .gps_status)
self.info = try container.decode(String.self, forKey: .info)
self.polyline = try container.decode(String.self, forKey: .polyline)
}
}
struct InputDataGrid: Codable {
}
我的 Bundle 是这样的:
extension Bundle {
func decode(_ file: String) -> [InputDataPois] {
// 1. Locate the Json File
guard let url = URL(string: file) else {
fatalError("Failed to locate \(file) in bundle")
}
// 2.Create a property for the Data
guard let data = try? Data(contentsOf: url) else {
fatalError("Failed to Load \(file) from bundle.")
}
// 3. Create a property for the data
let str = String(decoding: data, as: UTF8.self)
print("\(str)")
guard let loaded = try? JSONDecoder().decode(APIResponse.self, from: data).pois else {
fatalError("Failed to decode \(file) from bundle.")
}
// 4. Return the ready-to-use data
return loaded
}
}
在我看来我正在使用:
let speed: [InputDataPois] = Bundle.main.decode("https://cdn2.atudo.net/api/1.0/vl.php?type=0,1,2,3,4,5,6&box=52.36176390234046,10.588760375976562,52.466468685912744,11.159706115722656")
我得到的错误看起来像这样。
ErrorMessage
ConsoleError
在此先感谢您的帮助。
删除您的自定义 Codable 实现和编码密钥。它们不是必需的,编译器可以用这个简单的 JSON 为你生成它们。然后一切都应该工作。
这里的问题具体是你的 APIResponse 解码:
init(from decoder: Decoder) throws {
let container = try decoder.container(keyedBy: CodingKeys.self)
self.pois = try container.decode(APIResponse.self, forKey: .pois).pois
self.grid = try container.decode(APIResponse.self, forKey: .grid).grid
}
要解码一个 APIResponse,您尝试解码两个 APIResponse。这将再次尝试解码导致无限递归的 APIResponse。您没有看到的唯一原因是您的 JSON 包含数组,导致对 container(keyedBy:)
的第二次调用失败。尝试在 init(from:)
的第一行设置一个断点(或者如果你必须打印语句),你会看到它在失败之前被调用了第二次。
要解决这个问题,您需要解码属性的实际类型:
self.pois = try container.decode([InputDataPois].self, forKey: .pois)
但正如我所说,您的 JSON 格式中没有任何内容需要手动实现解码器,所以最好让编译器为您合成它。
你好,我叫 Nico,
我是 App 的完全初学者 programming/SwiftUI。 我正在尝试从网络 api 解析 json 数据,但不知何故我无法正确解析数据。我假设我的 json 结构不正确,但我找不到问题所在。
我从网上得到的 Json API 看起来像这样:
{
"pois": [
{
"id": "2635094451",
"lat": "52.410150",
"lat_s": "52.4",
"lng": "10.776630",
"lng_s": "10.8",
"street": "Röntgenstraße",
"content": "8137285512",
"backend": "0-239283152",
"type": "1",
"vmax": "50",
"counter": "0",
"create_date": "2021-11-18 13:21:50",
"confirm_date": "2021-11-18 13:21:43",
"gps_status": "-",
"info": " {\"qltyCountryRoad\":1,\"confirmed\":\"0\",\"gesperrt\":\"0\",\"precheck\":\"[Q1|21|0]\"}",
"polyline": ""
}
],
"grid": []
}
我的结构如下所示:
struct APIResponse: Codable {
let pois: [InputDataPois]
let grid: [InputDataGrid]
private enum CodingKeys: String, CodingKey {
case pois
case grid
}
init(from decoder: Decoder) throws {
let container = try decoder.container(keyedBy: CodingKeys.self)
self.pois = try container.decode(APIResponse.self, forKey: .pois).pois
self.grid = try container.decode(APIResponse.self, forKey: .grid).grid
}
}
struct InputDataPois: Codable, Identifiable {
let id:String
let lat:String
let lat_s:String
let lng:String
let lng_s:String
let street:String
let content:String
let backend:String
let type:String
let vmax:String
let counter:String
let create_date:String
let confirm_date:String
let gps_status:String
let info:String
let polyline:String
}
extension InputDataPois {
private enum CodingKeys: String, CodingKey {
case id
case lat
case lat_s
case lng
case lng_s
case street
case content
case backend
case type
case vmax
case counter
case create_date
case confirm_date
case gps_status
case info
case polyline
}
init(from decoder: Decoder) throws {
let container = try decoder.container(keyedBy: CodingKeys.self)
self.id = try container.decode(String.self, forKey: .id)
self.lat = try container.decode(String.self, forKey: .lat)
self.lat_s = try container.decode(String.self, forKey: .lat_s)
self.lng = try container.decode(String.self, forKey: .lng)
self.lng_s = try container.decode(String.self, forKey: .lng_s)
self.street = try container.decode(String.self, forKey: .street)
self.content = try container.decode(String.self, forKey: .content)
self.backend = try container.decode(String.self, forKey: .backend)
self.type = try container.decode(String.self, forKey: .type)
self.vmax = try container.decode(String.self, forKey: .vmax)
self.counter = try container.decode(String.self, forKey: .counter)
self.create_date = try container.decode(String.self, forKey: .create_date)
self.confirm_date = try container.decode(String.self, forKey: .confirm_date)
self.gps_status = try container.decode(String.self, forKey: .gps_status)
self.info = try container.decode(String.self, forKey: .info)
self.polyline = try container.decode(String.self, forKey: .polyline)
}
}
struct InputDataGrid: Codable {
}
我的 Bundle 是这样的:
extension Bundle {
func decode(_ file: String) -> [InputDataPois] {
// 1. Locate the Json File
guard let url = URL(string: file) else {
fatalError("Failed to locate \(file) in bundle")
}
// 2.Create a property for the Data
guard let data = try? Data(contentsOf: url) else {
fatalError("Failed to Load \(file) from bundle.")
}
// 3. Create a property for the data
let str = String(decoding: data, as: UTF8.self)
print("\(str)")
guard let loaded = try? JSONDecoder().decode(APIResponse.self, from: data).pois else {
fatalError("Failed to decode \(file) from bundle.")
}
// 4. Return the ready-to-use data
return loaded
}
}
在我看来我正在使用:
let speed: [InputDataPois] = Bundle.main.decode("https://cdn2.atudo.net/api/1.0/vl.php?type=0,1,2,3,4,5,6&box=52.36176390234046,10.588760375976562,52.466468685912744,11.159706115722656")
我得到的错误看起来像这样。
ErrorMessage ConsoleError
在此先感谢您的帮助。
删除您的自定义 Codable 实现和编码密钥。它们不是必需的,编译器可以用这个简单的 JSON 为你生成它们。然后一切都应该工作。
这里的问题具体是你的 APIResponse 解码:
init(from decoder: Decoder) throws {
let container = try decoder.container(keyedBy: CodingKeys.self)
self.pois = try container.decode(APIResponse.self, forKey: .pois).pois
self.grid = try container.decode(APIResponse.self, forKey: .grid).grid
}
要解码一个 APIResponse,您尝试解码两个 APIResponse。这将再次尝试解码导致无限递归的 APIResponse。您没有看到的唯一原因是您的 JSON 包含数组,导致对 container(keyedBy:)
的第二次调用失败。尝试在 init(from:)
的第一行设置一个断点(或者如果你必须打印语句),你会看到它在失败之前被调用了第二次。
要解决这个问题,您需要解码属性的实际类型:
self.pois = try container.decode([InputDataPois].self, forKey: .pois)
但正如我所说,您的 JSON 格式中没有任何内容需要手动实现解码器,所以最好让编译器为您合成它。