AngularFire V1.2 $firebaseArray() $loaded() only called once [duplicate]

问题

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

Currently, I'm using the following code:

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);
      }
    }; 
}]);

Page1:

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

Page2:

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

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.

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?

回答1:

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

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);
      }
    }; 
}]);

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.

Usage:

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

来源：https://stackoverflow.com/questions/50738504/angularfire-v1-2-firebasearray-loaded-only-called-once

标签

angularjs

firebase

firebase-realtime-database

angularfire

angular-promise