How do I delete a Firestore Document from a List in SwiftUI

Question

Here is my view model

import FirebaseFirestore
import FirebaseFirestoreSwift

struct Todo: Codable, Identifiable, Hashable {
    @DocumentID var id: String?
    var todoDetais: String?
}

This is how I'm showing the list ignore the typo in "details".

var body: some View {
    NavigationView {
        List {
            ForEach(viewModel.todos, id: \.self) { todo in
                VStack{
                    Text(todo.todoDetais!)
                }
            }
            .onDelete(perform: delete)
        }

My fetch data and mapping.

    func fetchData() {
    db.collection("todos").addSnapshotListener { (querySnapshot, error) in
        guard let documents = querySnapshot?.documents else {
            print("No documents")
            return
        }
        
        self.todos = documents.map { (QueryDocumentSnapshot)  -> Todo in
            let data = QueryDocumentSnapshot.data()
            let todoDetails = data["todo"] as? String ?? ""
            
            return Todo(todoDetais: todoDetails)
        }
    }
}

The delete logic, I can remove from a list but how do I delete from Firestore?

    func delete(at offsets: IndexSet) {
    viewModel.todos.remove(atOffsets: offsets)
    
    //I need to delete a firestore document at the index im removing at?
    
}

Answer 1

You can map the offsets to your Todo models by doing this:

offsets.map { viewModel.todos[$0] }

So, your delete function might look something like this:

func delete(at offsets: IndexSet) {
  offsets.map { viewModel.todos[$0] }.forEach { todo in 
    guard let todoID = todo.id else { return }
    db.collection("todos").document(todoID).delete() { err in
      if let err = err {
        print("Error removing document: \(err)")
      } else {
        print("Document successfully removed!")
      }
    }
  }
}

If you had a bunch, you could look into batching the requests, but this should get you started.