如何使用AngularFire对对象进行部分更新

问题描述

Angularfire 0.8中的 $ save（）让我感到困惑。

这是一个简单的例子 - 一个片段从我的controllers.js文件：

  .controller（'LandingPageController'，['$ scope'，'$ firebase'，function （$ scope，$ firebase）{
 $ scope.addNode = function（）{
 var FB = new Firebase（'https://protodb.firebaseio.com/testrecords/'）; 
 $ var fbr = $ firebase（FB）; 
 fbr。$ set（1，{firstname：'James'}）; 
} 
 $ scope.addAttribute = function（）{
 var FB = new Firebase（'https://protodb.firebaseio.com/testrecords/1'）; 
 var fbr = $ firebase（FB）。$ asObject（）; 
 fbr.lastname =Bond; 
 fbr。$ save（）; 
} 
}]）
  

当调用 addNode（）的时候，果然在我的firebase中创建了一个节点：

addAttribute（）被调用时，整个记录被替换，而不是我所期望的，这是'lastname'属性被添加。

$ b

我毫不怀疑误解了文档。任何人都可以帮忙吗？

更新：

好的，我需要等到对象被加载。现在，在将 addAttribute 更改为：

  $ scope.addAttribute = function（）{
 var FB = new Firebase（'https://protodb.firebaseio.com/testrecords/1'）; 
 var fbr = $ firebase（FB）。$ asObject（）; （）; 
 fbr。$ loaded（）。then（function（）{
 fbr.lastname =Bond; 
 fbr。$ save（）; 
}）; 
 
  

解决方案

：
$ b

1. a FirebaseObject （由 $ asObject返回（））没有 $ update 方法。


2. 当您调用 $ save（）在 FirebaseObject 完全加载之前，最终可能会删除其他属性
   

要修补现有的数据，您可以：

1. 或者等待整个对象（如你在更新问题时所做的那样）


2. 或直接调用 $ firebase。$ update

  $ firebase（FB）。$ update（{lastname：Bond} ）; 
  

最后一种方法的优点是不需要拉下整个对象，只需要更新单一财产。请注意，在大多数情况下，这可能是，但仍然...

The $save() in Angularfire 0.8 is confusing me.

Here's a minimal example - a snippet from my controllers.js file:

    .controller('LandingPageController', ['$scope','$firebase', function($scope,$firebase) {
        $scope.addNode = function() {
            var FB = new Firebase('https://protodb.firebaseio.com/testrecords/');
            var fbr = $firebase(FB);
            fbr.$set(1,{firstname: 'James'});
        }
        $scope.addAttribute = function() {
            var FB = new Firebase('https://protodb.firebaseio.com/testrecords/1');
            var fbr = $firebase(FB).$asObject();
            fbr.lastname = "Bond";
            fbr.$save();
        }
        }])

When addNode() is called, sure enough, a node is created in my firebase:

But when addAttribute() is called, the entire record is replaced, rather than what I expected, which was for the 'lastname' attribute to be added.

I've no doubt misunderstood the docs. Can anyone help?

Update:

OK, I needed to wait until the object was loaded. It works now, after changing addAttribute to:

    $scope.addAttribute = function() {
          var FB = new Firebase('https://protodb.firebaseio.com/testrecords/1');
          var fbr = $firebase(FB).$asObject();
          fbr.$loaded().then(function() {
              fbr.lastname = "Bond";
              fbr.$save();
          });
    }

解决方案

As you found out yourself already:

1. a FirebaseObject (as returned by $asObject()) does not have a $update method.
2. when you call $save() on a FirebaseObject before it is completely loaded, you may end up deleting other properties

To patch existing data you can:

1. Either wait for the entire object to be loaded (as you did in your update to the question)
2. Or call $firebase.$update directly

$firebase(FB).$update({ lastname: "Bond" });

This last approach has the advantage that you don't pull down the entire object, only to update a single property. Note that this is probably premature optimization in most cases, but still...

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