将数据添加到 firebase 时，如何在 Angularfire 上未发送数据时捕获错误? [英] How to Catch Error When Data is not Sent on Angularfire when adding data to firebase?

问题描述

我使用 angularfire 将数据保存到我的 Firebase 中.这是一个快速代码.

Im using angularfire to save data into my firebase. Here is a quick code.

$scope.users.$add({ 
            Name:$scope.username,
            Age:$scope.newage,
            Contact: $scope.newcontact,
          });

 alert('Saved to firebase');

我已成功将这些数据发送到我的 Firebase，但是如果这些数据未成功保存，我该如何捕获错误?有什么想法吗?

I am successful in sending these data to my firebase however how can I catch an error if these data are not saved successfully? Any ideas?

编辑

所以在实现 then() 函数之后.

So after implementing then() function.

$scope.users.$add({   
        Name:'Frank',
        Age:'20',
        Contact: $scope.newcontact,
      }).then(function(ref) {
 alert('Saved.');
 }).catch(function(error) {
 console.error(error); //or
 console.log(error);
 alert('Not Saved.');
 });

连接到互联网时.then() 函数很好.在显示警报之前，它会等待这些数据保存在 firebase 中.我想要的是它告诉我数据没有保存.当我关闭互联网连接并提交这些数据时，捕获错误功能未触发.

When connected to the internet. The then() function is fine. It waits for those data to be saved in firebase before showing the alert. What I want is for it to tell me that data is not saved. catch error function is not firing when i am turning off my internet connection and submitting those data.

推荐答案

当你调用 $add() 时，它会返回一个 promise.要检测数据何时保存，请实现 then().要检测何时保存失败，请实现 catch():

When you call $add() it returns a promise. To detect when the data was saved, implement then(). To detect when saving failed, implement catch():

var list = $firebaseArray(ref);
list.$add({ foo: "bar" }).then(function(ref) {
  var id = ref.key;
  console.log("added record with id " + id);
  list.$indexFor(id); // returns location in the array
}).catch(function(error) {
  console.error(error);
});

请参阅文档add().

检测何时由于没有网络连接而无法保存数据对于 Firebase 数据库来说是一个非常不同的问题.在这种情况下无法保存不是错误，而只是暂时的情况.这个条件不仅仅适用于这个 set() 操作，而是适用于所有读/写操作.因此，您应该通过 更全面地处理它检测连接状态:

To detect when the data cannot be saved due to not having a network connection is a very different problem when it comes to the Firebase Database. Not being able to save in this case is not an error, but merely a temporary condition. This condition doesn't apply just to this set() operation, but to all read/write operation. For this reason, you should handle it more globally, by detecting connection state:

var connectedRef = firebase.database().ref(".info/connected");

connectedRef.on("value", function(snap) {
  if (snap.val() === true) {
    alert("connected");
  } else {
    alert("not connected");
  }
});

通过侦听 .info/connected，您的代码可以知道用户未连接到 Firebase 数据库并根据您的应用的需要进行处理.

By listening to .info/connected your code can know that the user is not connected to the Firebase Database and handle it according to your app's needs.

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