问题
Upon the tap of a delete button. I am trying to delete a particular child out of my Firebase database. My problem is that I am unable to refer to the particular childByAutoId in my database therefore my application does not know what child to remove.
Firebase Database
DataServices File
import Foundation
import Firebase
import UIKit
let DB_BASE = FIRDatabase.database().reference().child("laboratory") //contains the root of our database
let STORAGE_BASE = FIRStorage.storage().reference()
class DataService {
static let ds = DataService()
//DB References
private var _REF_BASE = DB_BASE
private var _REF_STATION = DB_BASE.child("stations")
private var _REF_USERS = DB_BASE.child("users")
//Storage Reference
private var _REF_ITEM_IMAGE = STORAGE_BASE.child("item-pics")
var REF_BASE: FIRDatabaseReference {
return _REF_BASE
}
var REF_STATION: FIRDatabaseReference {
return _REF_STATION
}
var REF_USERS: FIRDatabaseReference {
return _REF_USERS
}
var REF_ITEM_IMAGES: FIRStorageReference {
return _REF_ITEM_IMAGE
}
//creating a new user into the firebase database
func createFirebaseDBUser(_ uid: String, userData: Dictionary<String, String>) {
REF_USERS.child(uid).updateChildValues(userData)
}
}
The information that I am trying to Delete is out of a tableViewCell. I have tried appending out the keys to an array but I am still unable to access the appropriate child to delete.
func tableView(_ tableView: UITableView, canEditRowAt indexPath: IndexPath) -> Bool {
return true
}
func tableView(tableView: (UITableView!), commitEditingStyle editingStyle: UITableViewCellEditingStyle, forRowAtIndexPath indexPath: (NSIndexPath!)) {
}
func tableView(_ tableView: UITableView, editActionsForRowAt indexPath: IndexPath) -> [UITableViewRowAction]? {
let currentStation = station.title
let stationRef = DataService.ds.REF_STATION.child(currentStation!)
let inventoryRef = stationRef.child("inventory")
var deleteAction = UITableViewRowAction(style: .default, title: "Delete") {action in
//delete items from firebase
self.items.remove(at: indexPath.row)
tableView.deleteRows(at: [indexPath as IndexPath], with: .fade)
}
var editAction = UITableViewRowAction(style: .normal, title: "Edit") { action in
}
return [deleteAction, editAction]
}
I have found no information online about this. Thanks in advance!
回答1:
Let's start with a simplified structure
-Uiiasidasod
item_name: "iMac"
-Yiimamsmdd
item_name: "MacBook"
A typical design pattern is to read these items from Firebase and store them in an array of dictionaries. That array is used as a datasource for the tableViews.
each dictionary is a key:value pair.
So the first node from above has a Firebase key (parent node name of "Uiiasidasod" and a value of "item_name: iMac" (note the value is a dictionary as well)
myArray[0] = ["Uiiasidasod": "item_name: 'iMac'"]
myArray[1] = ["Yiimamsmdd": "item_name: 'MacBook'"]
so when the user swipes row 1 in the table, you fetch the dictionary from the array, row 1. You get the key portion (the Firebase node name) and can then delete it from Firebase.
来源：https://stackoverflow.com/questions/40876616/how-to-check-for-value-in-firebase-that-is-held-under-a-autoid-child