我正在创建一个库存应用程序，以便跟踪实验室中保存的元素。在实验室中，有不同的站点，其中包含不同的项目，正如您所看到的，这些项目在我的 Firebase 数据库中结构正确。
当我尝试从 tableCell 中删除特定项目时，我的问题出现了。我可以从 UI 中删除它，但在 firebase 中数据仍然保留。我做了无数的研究，但找不到与这个特定问题相关的任何内容。
数据服务类
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)
}
}
库存 View Controller
import UIKit
import Firebase
class InventoryViewController: UIViewController, UITableViewDataSource, UITableViewDelegate, UIImagePickerControllerDelegate, UINavigationControllerDelegate {
var items = [Item]()
private var _station: Station!
private var _item: Item!
var sortIndex = 3
var imagePicker: UIImagePickerController!
static var imageCache: NSCache<NSString, UIImage> = NSCache()
var imageSelected = false
@IBOutlet weak var itemImageToAdd: UIImageView!
@IBOutlet weak var objectTextInput: UITextField!
@IBOutlet weak var brandTextInput: UITextField!
@IBOutlet weak var unitTextInput: UITextField!
@IBOutlet weak var amountTextInput: UITextField!
@IBOutlet weak var tableView: UITableView!
@IBOutlet var addItemView: UIView!
@IBOutlet weak var currentStationLabel: UILabel!
var station: Station {
get {
return _station
} set {
_station = newValue
}
}
override func viewDidLoad() {
super.viewDidLoad()
var currentStationName = station.title
currentStationLabel.text = currentStationName
self.items = []
let currentStation = station.title
let stationRef = DataService.ds.REF_STATION.child(currentStation!)
let inventoryRef = stationRef.child("inventory")
tableView.delegate = self
tableView.dataSource = self
imagePicker = UIImagePickerController()
imagePicker.allowsEditing = true
imagePicker.delegate = self
inventoryRef.observe(.value, with: { (snapshot) in
print(snapshot.value!)
self.items = []
if let snapshot = snapshot.children.allObjects as? [FIRDataSnapshot] {
for snap in snapshot {
print("SNAP: \(snap)")
if let itemDict = snap.value as? Dictionary<String, AnyObject> {
let key = snap.key
let item = Item(itemKey: key,
itemData: itemDict)
self.items.append(item)
}
}
}
self.tableView.reloadData()
})
}
func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell {
let item = items[indexPath.row]
if let cell = tableView.dequeueReusableCell(withIdentifier: "inventoryTableCell", for: indexPath) as? ItemCell {
if let img = InventoryViewController.imageCache.object(forKey: NSString(string: item.imageURL!)) {
cell.updateItemUI(item: item, img: img)
} else {
cell.updateItemUI(item: item)
}
return cell
} else {
return ItemCell()
}
}
func numberOfSections(in tableView: UITableView) -> Int {
return 1
}
func tableView(_ tableView: UITableView, numberOfRowsInSection section: Int) -> Int {
return items.count
}
func postToFirebase(itemImageURL: String) {
let post: Dictionary<String, AnyObject> = [
"objectLabel": objectTextInput.text! as AnyObject,
"brandLabel": brandTextInput.text! as AnyObject,
"unitLabel": unitTextInput.text! as AnyObject,
"amountLabel": amountTextInput.text! as AnyObject,
//post elsewhere as an image for future reference
"itemImageURL": itemImageURL as AnyObject,
]
let stationText = _station.title
let stationRef = DataService.ds.REF_STATION.child(stationText!)
let inventoryRef = stationRef.child("inventory")
let firebasePost = inventoryRef.childByAutoId()
firebasePost.setValue(post)
objectTextInput.text = ""
brandTextInput.text = ""
unitTextInput.text = ""
amountTextInput.text = ""
imageSelected = false
tableView.reloadData()
}
func imagePickerController(_ picker: UIImagePickerController, didFinishPickingMediaWithInfo info: [String : Any]) {
if let image = info[UIImagePickerControllerEditedImage] as? UIImage {
itemImageToAdd.image = image
imageSelected = true
} else {
print("Please select a valid image")
}
imagePicker.dismiss(animated: true, completion: nil)
}
@IBAction func backToStations(_ sender: Any) {
performSegue(withIdentifier: "backToStations", sender: nil)
}
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
//Insert code to delete values 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]
}
}
我的思考过程是在删除时调用 self_items.key 引用特定 tableCell 行的当前键。从那里我将使用当前的 key (即 autoID)并以这种方式删除该值。不幸的是，这会导致程序崩溃并出现致命的零错误。
最佳答案
我发现解决此问题的最佳方法是在删除操作中，从 Firebase 中删除该对象。不要从这里更改表格 View 。
然后在数据监听器中，检查数据何时返回为已删除(或 NULL)，然后将其从 TableView 数据源数组中删除并更新 TableView 。
关于ios - 如何在 Firebase 中显示 autoID 子项下保存的数据？，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/40954546/