尽管将正确的组传递给视图，但在 ViewModel 中获取的拼车 ID 不正确

Question

问题概述： 我正在开发一个 SwiftUI 应用程序，我需要在其中获取特定组（拼车）的事件。问题是 CalendarCell 视图无法正确获取所选组的事件。相反，尽管将正确的 GroupT 对象（其中包括正确的拼车 ID）传递给视图，它始终会获取默认组的事件。

预期行为： 当我选择拼车（由 GroupT 表示）时，我希望 CalendarCell 视图使用所选组的拼车 ID 来获取事件。但是，EventViewModel 中使用的拼车 ID 与所选组不匹配。相反，它始终显示最新的组。我正在使用 UserDefaults 来获取我的拼车 ID。

日历单元格视图：

struct CalendarCell: View {
    let group: GroupT
    @StateObject var eventViewModel: EventViewModel
    @State private var events: [Event] = []
    @State private var isShowingDailyEventPage = false

    init(group: GroupT) {
        self.group = group
        _eventViewModel = StateObject(wrappedValue: EventViewModel(group: group))  // Initialize EventViewModel with selected group
    }

    var body: some View {
        Text("Some Day")
            .onTapGesture {
                fetchDailyEvents()
            }
    }

   func fetchDailyEvents() {
        guard let carpoolIDString = UserDefaults.standard.string(forKey: "carpoolID") else {
            print("Carpool ID not found in UserDefaults")
            return
        }
        let joinCode = group.joinCode
        printCarpoolID()
        print("Retrieved Carpool ID from UserDefaults: \(carpoolIDString)")

        guard let carpoolID = UUID(uuidString: carpoolIDString) else {
            print("Invalid UUID string for Carpool ID: \(carpoolIDString)")
            return
        }

        print("Valid Carpool ID: \(carpoolID.uuidString)")

        let viewModel = EventViewModel(group: GroupT(carpoolID: carpoolID, carpoolName: "Example", admin: "admin", date_created: Date(), members: [], events: [], joinCode: joinCode))
        
        viewModel.fetchDailyEvents(forCarpoolID: carpoolID.uuidString, date: dateForCell()) { result in
            switch result {
            case .success(let events):
                DispatchQueue.main.async {
                    self.events = events
                }
            case .failure(let error):
                print("Error fetching events: \(error)")
            }
        }
    }

EventViewModel 功能：

func fetchDailyEvents(forCarpoolID carpoolID: String, date: Date, completion: @escaping (Result<[Event], Error>) -> Void) {
        // DateFormatter for the date string in ISO 8601 format
        let dateFormatter = DateFormatter()
        dateFormatter.dateFormat = "yyyy-MM-dd" // API expects this date format
        let dateString = dateFormatter.string(from: date)

        // Lowercase carpoolID for consistency
        let lowercasedCarpoolID = carpoolID.lowercased()

        // Debugging: Print carpool ID and formatted date
        print("Fetching events for Carpool ID: \(lowercasedCarpoolID) on Date: \(dateString)")

        // Construct the API URL
        guard let apiURL = URL(string: "http://localhost/api/events/\(lowercasedCarpoolID)/date/\(dateString)") else {
            print("Invalid API URL")
            completion(.failure(NetworkError.invalidRequest))
            return
        }

        // Debugging: Print the constructed API URL
        print("Constructed API URL: \(apiURL)")

        // Create URLRequest
        var request = URLRequest(url: apiURL)
        request.httpMethod = "GET"
        request.setValue("application/json", forHTTPHeaderField: "Content-Type")

        // Perform the network request
        let task = URLSession.shared.dataTask(with: request) { data, response, error in
            // Handle potential errors
            if let error = error {
                print("Network error: \(error.localizedDescription)")
                completion(.failure(NetworkError.invalidResponse))
                return
            }

            // Print the HTTP response status code
            if let httpResponse = response as? HTTPURLResponse {
                print("HTTP Response Status Code: \(httpResponse.statusCode)")
            }

            // Ensure data is not nil
            guard let data = data else {
                print("No data received")
                completion(.failure(NetworkError.invalidResponse))
                return
            }

            // Debugging: Print the raw JSON response
            if let jsonString = String(data: data, encoding: .utf8) {
                print("Received JSON: \(jsonString)")
            }

            do {
                // Decode the response as an array of Event
                let decoder = JSONDecoder()
                decoder.dateDecodingStrategy = .iso8601 // API uses ISO 8601 for date and time

                // Attempt decoding
                let events = try decoder.decode([Event].self, from: data)

                // Debugging: Print the decoded events
                print("Successfully decoded events: \(events)")
                completion(.success(events))
            } catch {
                // Print detailed decoding error information
                print("Decoding error: \(error.localizedDescription)")
                completion(.failure(error))
            }
        }
        task.resume()
    }

集团结构：

struct GroupT: Codable {
    let carpoolID: UUID
    let carpoolName: String
    let admin: String
    var members: [String]
    let date_created: Date
    let events: [Event]
    let joinCode: String
}

我尝试过的：

1. 我确保传递到 CalendarCell 的组是正确选择的组。
2. 我在 fetchDailyEvents 方法中打印 carpoolID 以确认它是正确的。
3. 尽管如此，视图中仍然使用了错误的组（最新的组），并且为错误的拼车 ID（最近创建的拼车）获取事件。
4. 我确保拼车 ID 正确保存在 userDefaults 中，它们只是获取不正确。

问题： 如何确保在获取特定组的事件时使用正确的拼车 ID，以及为什么 EventViewModel 没有反映所选组的拼车 ID？

Answer 1

• 将 EventsViewModel 重命名为 EventsFetcher。
• 将状态事件移至 EventsFetcher 内的已发布属性。
• 也将 fetchDailyEvents 移入。
• 以正常方式删除 View init 和 init @StateObject。

类似这样的：

struct CalendarCell: View {
    let group: Group
    @StateObject var eventsFetcher = EventsFetcher() // normal init
    \\ events moved to object
    @State private var isShowingDailyEventPage = false

    // init removed

    var body: some View {
        // display eventsFetcher.events
        Text("Some Day")
            .onTapGesture { [group] in 
                eventsFetcher.fetchDailyEvents(group) // do the fetch
            }
    }
}

class EventsFetcher: ObservableObject {
    @Published var events: [Event] = []

    func fetchDailyEvents(_ group: Group) {
        // fetch events and set on published var, then body will automatically be called.
    }
}