Duplicate Data from Firebase when I use .value

问题

I get duplicate data (old and updated data) in my UITableView whenever I update my data from firebase.

I am actually trying to create a realtime database for my UITableView.

var foodlist = [FoodModel]()

@objc func load_data() {
  Database.database().reference().child("Food").observe(.value) {
    (snapshot: DataSnapshot) in

    if let dict = snapshot.value as ? [String: AnyObject] {
      for child in dict.values {
        if let FoodimageText = child["image"] as ? String,
          let FoodnameText = child["name"] as ? String,
            let FoodpriceText = child["price"] as ? String {
              let post = FoodModel(FoodimageText: FoodimageText, FoodnameText: FoodnameText, FoodpriceText: FoodpriceText)
              self.foodlist.append(post)
            }
      }
      DispatchQueue.main.async {
        self.tableview_controller.reloadData()
      }
    }
  }
}

回答1:

var foodlist = [FoodModel]()

@objc func load_data() {
  Database.database().reference().child("Food").observe(.value) {
    (snapshot: DataSnapshot) in
    if let dict = snapshot.value as ? [String: AnyObject] {
      self.foodlist.removeAll() //add this
      for child in dict.values {
        if let FoodimageText = child["image"] as ? String,
          let FoodnameText = child["name"] as ? String,
            let FoodpriceText = child["price"] as ? String {
              let post = FoodModel(FoodimageText: FoodimageText, FoodnameText: FoodnameText, FoodpriceText: FoodpriceText)
              self.foodlist.append(post)
            }
      }
      DispatchQueue.main.async {
        self.tableview_controller.reloadData()
      }
    }
  }
}

回答2:

first check you only received one row of the data or complete nodes, sometimes you received complete data from firebase when adding a new row, if you received complete data from the firebase so, remove all items from the array after that append data in the array.

try this before calling the listener, foodlist.removeAll()

来源：https://stackoverflow.com/questions/62512632/duplicate-data-from-firebase-when-i-use-value

标签

swift

firebase

firebase-realtime-database