Firestore 响应 "cannot find 'cards' in scope"

Question

我按照这个 tutorial 从 firestore 获取数据并更改了我需要的与我的模型相对应的内容，但它一直响应“在范围内找不到 'cards'”，我不确定我做错了什么。（我想我的 mvvm 标签是对的）

VIEW

import SwiftUI

struct TestingView: View {

@ObservedObject private var viewModel = CardViewModel()

var body: some View {
    List(viewModel.cards) {
        Text(cards.name)
    }
    .onAppear() {
        self.viewModel.fetchData()
    }
  }
}

查看模型

import Foundation
import Firebase

class CardViewModel: ObservableObject {
@Published var cards = [Cards]()

private var db = Firestore.firestore()

func fetchData() {
 db.collection("cards").addSnapshotListener { (querySnapshot, error) in
  guard let documents = querySnapshot?.documents else {
    print("No documents")
    return
  }
  self.cards = documents.map { queryDocumentSnapshot -> Cards in
    let data = queryDocumentSnapshot.data()
      let name = data["name"] as? String ?? ""
      let pronoun = data["pronoun"] as? String ?? ""
      let bio = data["bio"] as? String ?? ""
      let profileURLString = data["profileURLString"] as? String ?? ""
      let gradiantColor1 = data["gradiantColor1"] as? UInt ?? 0
      let gradiantColor2 = data["gradiantColor2"] as? UInt ?? 0
      let gradiantColor3 = data["gradiantColor3"] as? UInt ?? 0
      
    return Cards(name: name, pronoun: pronoun, bio: bio, profileURLString:   profileURLString, gradiantColor1: gradiantColor1, gradiantColor2: gradiantColor2, gradiantColor3: gradiantColor3)
      }
    }
  }
}

型号

import Foundation

struct Cards: Identifiable {
    var id = UUID().uuidString
    var name: String
    var pronoun: String
    var bio: String
    var profileURLString: String

    var gradiantColor1: UInt
    var gradiantColor2: UInt
    var gradiantColor3: UInt

    var profileURL: URL {
        return URL(string: profileURLString)!
    }
 }

Answer 1

List 将为其尾随闭包提供一个元素——请参阅我的代码中的 card in。然后，您可以在 Text 元素中访问特定的 card。

var body: some View {
    List(viewModel.cards) { card in //<-- Here
        Text(card.name) //<-- Here
    }
    .onAppear() {
        self.viewModel.fetchData()
    }
  }
}

我建议您将 struct Cards 重命名为 struct Card，因为它是一张卡。那么，您的数组将是 @Published var cards = [Card]() —— 即 Card 的数组。从命名的角度来看，这会更有意义。

Firestore 响应 "cannot find 'cards' in scope"

Firestore responding with "cannot find 'cards' in scope"

mvvm

firebase

swift

google-cloud-firestore

swiftui