SwiftUI Firebase。删除所有项目而不仅仅是一个

Posted 2023-02-24

【中文标题】SwiftUI Firebase。删除所有项目而不仅仅是一个

【英文标题】：SwiftUI Firebase. Deletes all Items not just one

【发布时间】：2020-05-02 18:36:53

【问题描述】：

我想删除带有其 ID (let db = Firestore.firestore()db.collection("Warenkorb").document(i.id).delete()) 的项目。所以这是我的代码。可悲的是，当我删除一个项目时，集合中的所有项目也会被删除。为什么？有人可以帮我吗？

ForEach(cart.data)  i in
     HStack
         Image("pic").resizable().scaledToFit().frame(width: 50, height: 75, alignment: .leading).padding().foregroundColor(.black)
            Spacer()
            VStack(alignment: .leading)
                Text(i.name).font(.system(size: 25)).foregroundColor(.black)
                HStack
                Text(i.preis).font(.system(size: 20)).foregroundColor(.black)
              Text(i.size).font(.system(size: 20)).foregroundColor(.black)
                
         
       Spacer()
        Text("\(i.quantity)").font(.system(size: 25)).foregroundColor(.black)
       Spacer()
                       if self.remove

        Button(action: 
        let db = Firestore.firestore()
            db.collection("Warenkorb").document(i.id).delete()
            self.show.toggle()
            self.show.toggle()


                                    ) 
                        Image(systemName: "minus.circle.fill")
                                .resizable()
                        .frame(width: 20, height: 20)
                    .foregroundColor(.red)

            
                        
        Spacer()

     
     .background(Color("Color-1")).frame(width: 350, height:  100).cornerRadius(30).padding(.leading)

【参考方案1】：

您不应在 SwiftUI 视图中添加数据访问代码。相反，实现一个视图模型（以及可选的存储库）来管理您的数据。

我已经稍微修改了你的代码：

查看

struct ShoppingCartView: View 
  @ObservedObject var viewModel: ShoppingCartViewModel

  var body: some View 
    List 
      ForEach(viewModel.lineItems)  lineItem in
        VStack(alignment: .leading) 
          Text(lineItem.title)
            .font(.headline)
        
      
      .onDelete  indexSet in
        self.viewModel.deleteLineItems(at: indexSet)
      
    
  

查看模型

import Foundation
import FirebaseFirestore
import FirebaseFirestoreSwift
import Combine

class ShoppingCartViewModel: ObservableObject 
  @Published var lineItems = [LineItem]()

  private var db = Firestore.firestore()
  private var listenerRegistration: ListenerRegistration?

  private var cancellables = Set<AnyCancellable>()

  init() 
    fetchData()
  

  deinit 
    unregister()
  

  func unregister() 
    if listenerRegistration != nil 
      listenerRegistration?.remove()
    
  

  func fetchData() 
    unregister()

    listenerRegistration = db.collection("shoppingCart").addSnapshotListener  (querySnapshot, error) in
      guard let documents = querySnapshot?.documents else 
        print("No documents")
        return
      

      self.lineItems = documents.compactMap  queryDocumentSnapshot -> LineItem? in
        let lineItem = try? queryDocumentSnapshot.data(as: LineItem.self)
        return lineItem
      
    
  

  func deleteLineItems(at offsets: IndexSet) 
    let itemsToDelete = offsets.lazy.map  self.lineItems[$0] 
    itemsToDelete.forEach  lineItem in
      if let id = lineItem.id 
        db.collection("shoppingCart").document(id).delete()