iOS Swift FIrebase：将数据移动到另一个firebase ref [英] iOS Swift FIrebase: moving data to another firebase ref

问题描述

我有一个简单的购物清单应用程序由firebase支持/同步，以及多个用户添加的项目。我已经为GroceryItem和Users创建了数据结构。

I have a simple shopping list app backed/synced by a firebase and items added by multiple users. I've created data structs for "GroceryItem" and "Users".

我的应用程序的一个功能是你可以单击单元格，它会在旁边放置一个复选标记该项目以及将已完成的bool更改为true。

One feature of my app is that you can click the cell and it will put a checkmark next to the item as well as change a bool of "completed" to true.

我正在尝试创建一个按钮，它会将所有选中的标记项目移动到单独列表称为历史。

I'm trying to make a button where it will it will moved all check marked items to a separate list called "history".

以下是我多次失败的尝试之一。我还包括了XCode给我的错误：

Below is one of my many failed attempts at this. I also included the error that XCode is giving me:

'Element'（又名'AnyObject'）不能转换为'FDataSnapshot';您的意思是使用强制垂头丧气的

@IBAction func itemsBoughtACTION(sender: AnyObject) {
        ref.queryOrderedByChild("completed").observeEventType(.Value,
            withBlock: { snapshot in

        for item in snapshot.children {
            var lastItem = GroceryItem(item)

            }
        })
    }

编辑：我只想数据已经存储在火力一些数据，其移动到另一个火力点位置，并删除原

I just want to data some data already stored in firebase, move it to another firebase location and delete the original.

推荐答案

过程是：查询您想要的数据，将其写入另一个节点，然后将其从原始节点中删除。

The process is: query for the data you want, write it out to another node, and then delete it from the original node.

您的代码胜过'因为它期望从UI而不是FDataSnapshot传递控件。如果您已完成查询并拥有数据集，则应创建一个函数，该函数将FDataSnapshot作为参数传递并相应地处理它。

Your code above won't work as it's expecting to be passed a control from the UI instead of a FDataSnapshot. If you have already done the query and have the dataset, you should create a function that would be passed a FDataSnapshot as a parameter and process it accordingly.

简化答案，假设您需要获取快照并在单击按钮时处理它。

To simplify the answer, assume that you need to get the snapshot and process it when the button is clicked.

有很多不同的方法可以解决这个问题，这是一个概念选项（未经测试不要复制粘贴）

There's a lot of different ways to approach this, here's one conceptual option ( untested so don't copy paste)

        //method is called when a button in the UI is clicked/tapped.
        @IBAction func itemsBoughtACTION(sender: AnyObject) {

           let rootRef = Firebase(url:"https://your-Firebase.firebaseio.com")

           let groceryRef = rootRef.childByAppendingPath("groceryLists")

           //get each child node of groceryRef where completed == true
           groceryRef.queryOrderedByChild("completed").queryEqualToValue(true)
       .observeEventType(.ChildAdded, withBlock: { snapshot in

              //set up a history node and write the snapshot.value to it
              // using the key as the node name and the value as the value.
              let historyNode = rootRef.childByAppendingPath("history")
              let thisHistoryNode = historyNode.childByAppendingPath(snapshot.key)
              thisHistoryNode.setValue(snapshot.value) //write to the new node

              //get a reference to the data we just read and remove it
              let nodeToRemove = groceryRef.childByAppendingPath(snapshot.key)
              nodeToRemove.removeValue();

           })

        }

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