如何在 $asArray 返回的列表中扩展返回的对象? [英] How to extend returned objects in the list returned by $asArray?
问题描述
我在使用新方法(不是装饰数组本身)装饰由 $asArray 在 angularfire 中返回的列表中的对象时遇到问题.
I'm having trouble decorate the objects in my list returned by $asArray in angularfire with a new method (not decorating the array itself).
angularfire 文档似乎表明,正确的方法是在工厂中为 $FirebaseArray 覆盖 $$ added 方法,返回一个新对象,该对象封装或扩展传递给该方法的快照.来自 文档一个>:
The angularfire documentation seems to suggest that the right way to do this is to override the $$added method in the factory for $FirebaseArray, returning a new object that either encapsulates or extends the snapshot that gets passed in to that method. From the documentation:
// an object to return in our JokeFactory
app.factory("Joke", function($firebaseUtils) {
function Joke(snapshot) {
this.$id = snapshot.name();
this.update(snapshot);
}
Joke.prototype = {
update: function(snapshot) {
// apply changes to this.data instead of directly on `this`
this.data = snapshot.val();
},
makeJoke: function() {
alert("Why did the " + this.animal + " cross the " + this.obstacle + "?");
},
toJSON: function() {
// since we didn't store our data directly on `this`, we need to return
// it in parsed format. We can use the util function to remove $ variables
// and get it ready to ship
return $firebaseUtils.toJSON(this.data);
}
};
return Joke;
});
app.factory("JokeFactory", function($FirebaseArray, Joke) {
return $FirebaseArray.$extendFactory({
// change the added behavior to return Joke objects
$$added: function(snap) {
return new Joke(snap);
},
// override the update behavior to call Joke.update()
$$updated: function(snap) {
this.$getRecord(snap.name()).update(snap);
}
});
});
但是,当我在我的代码中执行此操作时,没有任何内容添加到数组中,尽管我可以从输出到控制台看到它正在被调用.
However, when I do this in my code, nothing ever gets added to the array, although I can see from outputting to the console that it is getting called.
var printMessageObjConstructor = function(snap) {
this.$id = snap.name();
this.snapshot = snap;
this.$update = function(snap) {
this.snapshot = snap;
};
this.printMessage = function() {
return this.author + "'s question is: " + this.body;
};
};
var ref = new Firebase("https://danculley-test.firebaseio.com/questions");
//What Am I Doing Wrong Here?
var arrayFactory = $FirebaseArray.$extendFactory({
$$added: function(snap, prevChild) {
var x = new printMessageObjConstructor(snap);
console.log("I am being called from FirebaseDecoratedCtlOverloadAddedinNewObj.");
return x;
},
$createObject: function(snap) {
return new printMessageObjConstructor(snap);
},
$$updated: function(snap) {
var i = this.$indexFor(snap.name());
var q = this.$list[i];
q.$update(snap);
}
});
var sync = $firebase(ref, {arrayFactory:arrayFactory});
var list = sync.$asArray();
list.$loaded(function(list) {
$scope.questions = list;
});
我已经建立了一个新的 plunk 以通过其他几个用例来展示这个问题我试过的.(我添加的实际方法更复杂,与视图无关,但我想做一些简单的事情来重现问题.)
I've set up a new plunk stripped down to show the issue with a couple other use cases that I've tried. (The actual method I'm adding is more complex and isn't related to the view, but I wanted to do something simple to reproduce the issue.)
我认为问题在于我不太明白 $$ added 究竟应该返回什么,或者除了返回要存储的 $$ added 值之外还有哪些额外的行为.在原型或 $FirebaseArray 上似乎也没有真正添加 $$ 来作为超级调用以获得默认行为.有人能指出我正确的方向吗?
I think the issue is that I don't quite understand what exactly $$added is supposed to return, or what additional behavior beside returning the value to be stored $$added is supposed to have. There also doesn't really seem to be an $$added on the prototype or on $FirebaseArray to call as a super to get the default behavior. Can someone point me in the right direction?
更新
为了他人的利益,在查看了 Kato 发布的类似内容后,我能够通过添加以下内容来解决问题,除了下面的注释行外,几乎所有内容都是直接从源代码复制的.
For the benefit of others, after reviewing the like that Kato posted, I was able to solve the issue by adding the following, almost all copied directly from the source except for the commented line below.
$$added: function(snap, prevChild) {
var i = this.$indexFor(snap.name());
if( i === -1 ) {
var rec = snap.val();
if( !angular.isObject(rec) ) {
rec = { $value: rec };
}
rec.$id = snap.name();
rec.$priority = snap.getPriority();
$firebaseUtils.applyDefaults(rec, this.$$defaults);
//This is the line that I added to what I copied from the source
angular.extend(rec, printMessageObj);
this._process('child_added', rec, prevChild);
}
}
推荐答案
为了他人的利益,在查看了 Kato 发布的链接后,我能够通过添加以下内容来解决问题,几乎都是直接从源代码复制的除了下面的注释行.
For the benefit of others, after reviewing the link that Kato posted, I was able to solve the issue by adding the following, almost all copied directly from the source except for the commented line below.
$$added: function(snap, prevChild) {
var i = this.$indexFor(snap.name());
if( i === -1 ) {
var rec = snap.val();
if( !angular.isObject(rec) ) {
rec = { $value: rec };
}
rec.$id = snap.name();
rec.$priority = snap.getPriority();
$firebaseUtils.applyDefaults(rec, this.$$defaults);
//This is the line that I added to what I copied from the source
angular.extend(rec, printMessageObj);
this._process('child_added', rec, prevChild);
}
}
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