JSON 到 SwiftData 的 JSON 解码在 ObservationRegistrar 以错误告终

问：

我正在为适用于 iOS17 和 SwiftData 的 SwiftUI 应用程序而苦苦挣扎。我正在尝试从 JSON 源下载数据并将数据存储在 SwiftData 中。我可以将数据下载并解码为 Swift 结构，但无法使用 SwiftData @Model类执行此操作。下面的代码包括 struct 和 SwiftData 过程。SwiftData 类是 SDTopLevel 和 SDFuelStation，结构是 TopLevelX 和 FuelStationX。FuelStationListView 中的按钮调用任一 loadDataSD 或 loadDataX。URL 正确且包含演示密钥。

struct FuelStationListView: View {

    @Environment(\.modelContext) var context
    @Query(sort: \SDFuelStation.stationName) var fuelStations: [SDFuelStation]

    @State private var sdTopLevel: SDTopLevel?
    @State private var topLevel: TopLevelX?

    var body: some View {
        NavigationStack {
            Button("Fetch") {
                Task {
                    await loadDataX()//works
                    //await loadDataSD()//does not work
                }
            }
            List {
                ForEach(fuelStations) { fuelStation in
                    Text(fuelStation.stationName)
                }
            }
            .navigationTitle("Fuel Stations")
        }//nav
    }//body

    func loadDataSD() async {

        guard let url = URL(string: "https://developer.nrel.gov/api/alt-fuel-stations/v1.json?api_key=DEMO_KEY&limit=10") else {
            print("Invalid URL")
            return
        }

        do {
            let (data, response) = try await URLSession.shared.data(from: url)
            guard (response as? HTTPURLResponse)?.statusCode == 200 else {
                print(response)
                return
            }
        
            let decoder = JSONDecoder()
            decoder.keyDecodingStrategy = .convertFromSnakeCase
            let decodedResponse = try decoder.decode(SDTopLevel.self, from: data)
            print(decodedResponse)
        
            sdTopLevel = decodedResponse
            print("sdTopLevel.fuelStations.count is \(sdTopLevel?.fuelStations.count ?? 1000)")

        } catch {
            print("Invalid Data")
        }

    }//load data

    func loadDataX() async {

        guard let url = URL(string: "https://developer.nrel.gov/api/alt-fuel-stations/v1.json?api_key=DEMO_KEY&limit=10") else {
            print("Invalid URL")
            return
        }

        do {
        
            let (data, response) = try await URLSession.shared.data(from: url)
            guard (response as? HTTPURLResponse)?.statusCode == 200 else {
                print(response)
                return
            }
        
            let decoder = JSONDecoder()
            decoder.keyDecodingStrategy = .convertFromSnakeCase
            let decodedResponse = try decoder.decode(TopLevelX.self, from: data)
        
            self.topLevel = decodedResponse
            print("topLevel.fuelStations.count is \(topLevel?.fuelStations.count ?? 0)")

            for station in decodedResponse.fuelStations {
                print(station.stationName)
            }
        
            self.topLevel = nil

        } catch {
            print("Invalid Data")
        }

    }//load data

}//struct fuel Station list view

和数据：

@Model
class SDFuelStation: Codable {

    enum CodingKeys: CodingKey {
        case id, city, stationName, streetAddress
    }//enum

    public var id: Int

    var stationName: String = ""
    var streetAddress: String = ""
    var city: String = ""

    public init(stationName: String, streetAddress: String, city: String) {
        self.id = 0
        self.stationName = stationName
        self.streetAddress = streetAddress
        self.city = city
    }

    required public init(from decoder: Decoder) throws {
        let container = try decoder.container(keyedBy: CodingKeys.self)
        id = try container.decode(Int.self, forKey: .id)
        stationName = try container.decode(String.self, forKey: .stationName)
        streetAddress = try container.decode(String.self, forKey: .streetAddress)
        city = try container.decode(String.self, forKey: .city)
    }//required init

    public func encode(to encoder: Encoder) throws {
        var container = encoder.container(keyedBy: CodingKeys.self)
    
        try container.encode(id, forKey: .id)
        try container.encode(stationName, forKey: .stationName)
        try container.encode(streetAddress, forKey: .streetAddress)
        try container.encode(city, forKey: .city)
    }

}//class

struct TopLevelX: Codable {
    let fuelStations: [FuelStationX]
}

struct FuelStationX: Codable {

    let id: Int

    var stationName: String = ""
    var streetAddress: String = ""
    var city: String = ""

}//struct

错误出在 getter 的模型代码中：

任何指导将不胜感激。Xcode 15.0 iOS的17

编辑： 我错误地错过了 SDTopLevel 类：

@Model
class SDTopLevel: Codable {

    enum CodingKeys: CodingKey {
        case fuelStations
    }

    var fuelStations: [SDFuelStation]

    init(fuelStations: [SDFuelStation]) {
        self.fuelStations = fuelStations
    }

    required public init(from decoder: Decoder) throws {
        let container = try decoder.container(keyedBy: CodingKeys.self)
        fuelStations = try container.decode([SDFuelStation].self, forKey: .fuelStations)
    }

    public func encode(to encoder: Encoder) throws {
        var container = encoder.container(keyedBy: CodingKeys.self)
        try container.encode(fuelStations, forKey: .fuelStations)
    }

}

var fuelStations 的代码展开如下，错误在行上：return self.getValue（forKey： .fuelStations），错误是“Thread 10： EXC_BREAKPOINT （code=1， subcode=0x1a8a5303c）”

{
    @storageRestrictions(accesses: _$backingData, initializes: _fuelStations)
        init(initialValue) {
                    _$backingData.setValue(forKey: \.fuelStations, to: initialValue)
                    _fuelStations = _SwiftDataNoType()
        }

    get {
                    _$observationRegistrar.access(self, keyPath: \.fuelStations)
                    return self.getValue(forKey: \.fuelStations)
        }

    set {
                    _$observationRegistrar.withMutation(of: self, keyPath: \.fuelStations) {
                            self.setValue(forKey: \.fuelStations, to: newValue)
                    }
        }
}