AngularFire V1.2 $ firebaseArray()$ loaded()仅调用一次 [英] AngularFire V1.2 $firebaseArray() $loaded() only called once

问题描述

我在数组上使用AngularFire和promises(在firebaseArray()上的$loaded()).

I am using AngularFire and promises on arrays ($loaded() on firebaseArray()).

当前，我正在使用以下代码:

Currently, I'm using the following code:

问题:我转到第1页，数据已加载并且一切正常.转到第2页，然后返回第1页.现在$loaded()直到我刷新整页后才起作用.我该如何解决这个问题?

Problem: I go to page1, the data is loaded and all fine. Go to page 2 and come back to page1. Now the $loaded() doesn't work until I do a full page refresh. How do I fix this problem?

app.factory('Items', ['FBURL', '$firebaseArray', function(FBURL, $firebaseArray) {
    return {
      ofCategory: function(catId){
        var ref = new Firebase(FBURL);
        var refSearch = new Firebase.util.NormalizedCollection(...).select(...).ref(); 
        var allItems= refSearch.orderByChild(...);
        return $firebaseArray(allItems);
      }
    }; 
}]);

第1页:

function readData() { 
  if($scope.Items) { 
     $scope.Items.$destroy();
     $scope.Items= null;
  }   
  $scope.Items = Items.ofCategory($routeParams.id);
  $scope.Items.$loaded().then(function(itm) {
        ...
  });
}

第2页:

$scope.Items= Items.ofCategory($routeParams.id);

Firebase文档 ^{$loaded()返回一个诺言，该诺言在从我们的数据库中下载初始记录后就解决了.这是仅调用一次，应该小心使用"，这可能就是我在这里得到的.}

The Firebase documentation¹ says: "$loaded() returns a promise which resolves after the initial records have been downloaded from our database. This is only called once and should be used with care", and that is probably what I get here.

我尝试过的操作:如图所示，在第1页的readData()函数中，我在执行任何新加载之前销毁了$scope.Items变量.但是它似乎没有做任何事情. AFAIU，$loaded()在firebaseArray()上运行，因此销毁$scope数组可能无济于事.因此，在没有完全刷新页面的情况下我应该怎么做才能使这项工作呢?

What I've tried: As shown, in my readData() function on Page1, I destroy the $scope.Items variable before any new load. But it doesn't seem to be doing anything. AFAIU, $loaded() is working on firebaseArray(), so destroying the $scope array might not help much. So, what else should I do to make this work without needing to fully refresh the page?

推荐答案

我听说应该避免AngularFire，这似乎是一个很好的理由.

I have heard that AngularFire should be avoided and this looks like a good reason.

直接使用firebase API:

Use the firebase API directly:

app.factory('FbItems', ['FBURL', '$q', function(FBURL, $q) {
    return {
      ofCategory: function(catId){
        var ref = new Firebase(FBURL);
        var refSearch = new Firebase.util.NormalizedCollection(...).select(...).ref(); 
        var allItems= refSearch.orderByChild(...);
        var promise = allItems.once('value').then(function(snapshot) {
            return snapshot.val();
        });
        return $q.when(promise);
      }
    }; 
}]);

使用 $q.when .只有在AngularJS执行上下文中应用的操作才能受益于AngularJS数据绑定，异常处理，属性监视等.

It is important to convert the ES6 promise to an AngularJS $q promise with $q.when. Only operations which are applied in the AngularJS execution context will benefit from AngularJS data-binding, exception handling, property watching, etc.

用法:

function readData() { 
  promise = FbItems.ofCategory($routeParams.id);
  promise.then(function(items) {
      $scope.Items = items;
  }).catch(function(error) {
      console.log(error);
  });
}

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