是否可以重命名Firebase实时数据库中的某个键？ [英] Is it possible to rename a key in the Firebase Realtime Database?

问题描述

让我们使用下面的数据：

我使用set（）来写入数据。
现在，我希望用户编辑它们的 bookTitle ，它需要在两个地方都改变。我尝试使用更新（），但我似乎无法使其工作。我只能编辑 bookInfo 不在 books 中的 bookTitle 。



移动不是一个选项，因为它会擦除 bookData 。
我也尝试使用push（），但是我不能正确搜索，因为我没有pushID（我需要搜索，因为用户不能有两本相同的名称）

那么，有没有办法更新键值？
或者，有没有更好的方法呢？我接受建议。谢谢！

更新：这就是我目前用来更新 bookInfo < code $>

$ $ p $ var bookName = document.getElementById（'bookName'）.value;
$ b $ firebase.database（）。ref（'books /'+ bookName +'/ bookInfo'）.update（{
bookTitle：bookName
））;





解决方案

我想我明白你想要做什么。 Firebase没有通过更新重命名部分路径的概念。相反，您必须完全删除现有的节点并重新创建它。你可以这样做：

  var booksRef = firebase.database（）。ref（'books'）; 
 booksRef.child（oldTitle）.once（'value'）。then（function（snap）{
 var data = snap.val（）; 
 data.bookInfo.bookTitle = newTitle; 
 var update = {}; 
 update [oldTitle] = null; 
 update [newTitle] = data; 
 return booksRef.update（update）; 
}） ; 
  

这将从 books / oldTitle 并在 books / newTitle 中重新填充新标题。

警告：这依赖于读取数据，然后执行第二个异步更新。如果您可能有多个用户同时操作相同的数据，则可能会导致问题。您可以使用交易以原子方式执行此操作，但如果 / books 是一个包含许多节点的顶级资源，可能会导致性能问题。

一次编辑数据，上面的解决方案是好的。如果没有，您可能需要考虑使用非用户控制的标识符，例如推送标识。

I was wondering, is there a way to update the key value?

Let´s use the following data:

I am using set() to write the data. Now, I want the user to edit their bookTitle and it needs to change on both places. I tried using update() but I can´t seem to make it work. I can only edit the bookTitle in bookInfo NOT on books.

Moving is not an option because it will erase the bookData. I also tried writing using push() but then, I can´t search properly because I don´t have the pushID (I need the search because users can't have two books with the same name)

So, is there a way to update the key value? or, is there a better approach to this? I accept suggestions. Thank you!

Update: This is what I´m currently using to update the book title inside bookInfo

var bookName = document.getElementById('bookName').value;

firebase.database().ref('books/' + bookName + '/bookInfo').update({
    bookTitle : bookName
});

解决方案

I think I see what you're trying to do. Firebase doesn't have the concept of "renaming" a part of the path via update. Instead you will have to completely remove the existing node and recreate it. You can do that like so:

var booksRef = firebase.database().ref('books');
booksRef.child(oldTitle).once('value').then(function(snap) {
  var data = snap.val();
  data.bookInfo.bookTitle = newTitle;
  var update = {};
  update[oldTitle] = null;
  update[newTitle] = data;
  return booksRef.update(update);
});

This will remove the info from books/oldTitle and re-populate it with a new title in books/newTitle.

Caveat: This relies on reading the data and then performing a second async update. If you are likely to have multiple users operating on the same data at the same time this could cause issues. You could use a transaction to do this atomically but if /books is a top-level resource with many nodes that may cause performance problems.

If one person is likely to edit the data at a time, the above solution is fine. If not, you may want to consider using a non-user-controlled identifier such as a push id.

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