使用AngularFire v2获取关键值的一点点清晰？ [英] A little clarity on getting key values using AngularFire v2?
问题描述
对不起，这有点疯狂：
假设我想获得一个项目的标题和.priority键加载时的值。
首先让我们看看每个东西的布局：
$ scope.items = $ firebase（新的Firebase（https：//****.firebaseio.com））;
$ b $ scope.items。$ on（'loaded'，function（）{
console.log（$ scope.items）;
}）;
我们得到：
>对象{$ bind：function，$ add：function，$ save：function，$ set：function，$ remove：function ...}
> $ add：function（item，cb）{
> $ bind：function（scope，name）{
> $ child：function（key）{
> $ getIndex：function（）{
> $ on：function（type，callback）{
> $ remove：function（key）{
> $ save：function（key）{
> $ set：function（newValue）{
>这是我的项目：对象
$$ hashKey：012
$ id：这是我的项目
$ priority：2884707
title：这是我的项目
__proto__：Object
> __proto__：Object
看起来不错，让我们试着抓住$ priority：
console.log（$ scope.items。$ child（'$ priority'））;
糟糕：
未捕获错误：Firebase.child失败：第一个参数是无效路径：$ priority。路径必须是非空字符串，不能包含。，＃，$，[或]
好的，我们现在就跳过这个题目，试试这个题目：
的console.log（$ scope.items $子（ '标题'））;
>对象{$ bind：function，$ add：function，$ save：function，$ set：function，$ remove：function ...}
> $ add：function（item，cb）{
> $ bind：function（scope，name）{
> $ child：function（key）{
> $ getIndex：function（）{
> $ on：function（type，callback）{
> $ remove：function（key）{
> $ save：function（key）{
> $ set：function（newValue）{
> __proto__：对象
无标题
好吧，让我们以不同的方式尝试：
var firstItem = $ scope.items。$ getIndex（）[0]; //以优先级顺序返回$ ids
console.log（$ scope.items。$ child（firstItem））;
>对象{$ bind：function，$ add：function，$ save：function，$ set：function，$ remove：function ...}
> $ add：function（item，cb）{
> $ bind：function（scope，name）{
> $ child：function（key）{
> $ getIndex：function（）{
> $ on：function（type，callback）{
> $ remove：function（key）{
> $ save：function（key）{
> $ set：function（newValue）{
title：这是我物品的标题
> __proto__：Object
但现在没有优先权！
厨房水槽在电脑时代宣誓：
console.log （$ scope.items.title）;
> undefined
console.log（$ scope.items [0] .title）;
> Uncaught TypeError：无法读取未定义的属性'title'
$ b console.log（Object.keys（$ scope.items））;
> $$，$ $，$ $，$ $，$ $，$ $，$ $， c> 我错过了什么？我可以设法得到'标题'通过做两次掉头（弄清楚什么项目的$ id是使用'$ getIndex（）'，抓住第n项，然后使用'$ child（）'再次调用），但即使这不符合优先顺序。有没有一种更简单的方法从AngularFire v2中获取关键值？或者任何方式来获得$优先？
我相信我/遇到同样的问题。希望这与你的经验有关。即：
$ b
$ scope.items = $ firebase（new Firebase（https：// xxxxxx .firebaseio.com））;
$ scope.items $ on（'loaded'，function（）{
console.log（$ scope.items ['some key']）; //这个写入未定义到控制台
}）;
我注意到这个确实有效依靠加载的事件。例如在HTML中：
$ b
< a href =＃data-ng-click = logItem（）>点击我< / a>
和在JS中：
$ scope.items = $ firebase（新的Firebase（https://xxxxxx.firebaseio.com））;
$ scope.logItem = function（）{
console.log（$ scope.items ['some key']）; / /这工程
点击点击我链接记录我的项目控制台如预期。
感觉像
加载时间的集合没有完全填充来自firebase的基础项目。 Sorry for the length of this but it's driving me a little bit crazy:
Let's say I want to get an item's "title" and ".priority" key values when it loads.
First let's see how every thing's laid out:
$scope.items = $firebase(new Firebase("https://****.firebaseio.com"));
$scope.items.$on('loaded', function() {
console.log($scope.items);
});
With that we get:
> Object {$bind: function, $add: function, $save: function, $set: function, $remove: function…}
> $add: function (item, cb) {
> $bind: function (scope, name) {
> $child: function (key) {
> $getIndex: function () {
> $on: function (type, callback) {
> $remove: function (key) {
> $save: function (key) {
> $set: function (newValue) {
> this is my item: Object
$$hashKey: "012"
$id: "this is my item"
$priority: 2884707
title: "this is the title of my item"
__proto__: Object
> __proto__: Object
Looks good, let's try to grab that $priority:
console.log($scope.items.$child('$priority'));
Oops:
Uncaught Error: Firebase.child failed: First argument was an invalid path: "$priority". Paths must be non-empty strings and can't contain ".", "#", "$", "[", or "]"
Fine, we'll skip that for now and just try for the title:
console.log($scope.items.$child('title'));
> Object {$bind: function, $add: function, $save: function, $set: function, $remove: function…}
> $add: function (item, cb) {
> $bind: function (scope, name) {
> $child: function (key) {
> $getIndex: function () {
> $on: function (type, callback) {
> $remove: function (key) {
> $save: function (key) {
> $set: function (newValue) {
> __proto__: Object
No title.
Okay, let's try it a different way :
var firstItem = $scope.items.$getIndex()[0]; //returns $ids in order of priority
console.log($scope.items.$child(firstItem));
> Object {$bind: function, $add: function, $save: function, $set: function, $remove: function…}
> $add: function (item, cb) {
> $bind: function (scope, name) {
> $child: function (key) {
> $getIndex: function () {
> $on: function (type, callback) {
> $remove: function (key) {
> $save: function (key) {
> $set: function (newValue) {
title: "this is the title of my item"
> __proto__: Object
But now there's no priority!
Kitchen sink swearing at the computer time:
console.log($scope.items.title);
> undefined
console.log($scope.items[0].title);
> Uncaught TypeError: Cannot read property 'title' of undefined
console.log(Object.keys($scope.items));
> ["$bind", "$add", "$save", "$set", "$remove", "$child", "$on", "$getIndex"]
What am I missing? I can manage to get the 'title' by doing a couple U-turns, (figuring out what the item's $id is using '$getIndex()', grabbing the nth item and then making another call using '$child()' ), but even that doesn't work for $priority. Is there an easier way to get key values from within AngularFire v2? Or any way at all to get the $priority?
I believe I am / was experiencing the same issue. Hopefully this is related to your experience. Namely:
$scope.items = $firebase(new Firebase("https://xxxxxx.firebaseio.com"));
$scope.items.$on('loaded', function() {
console.log($scope.items['some key']); // this writes undefined to console
});
What I noticed is that this actually does work if I don't rely on the loaded event. E.g in the HTML:
<a href="#" data-ng-click="logItem()">click me</a>
and in the JS:
$scope.items = $firebase(new Firebase("https://xxxxxx.firebaseio.com"));
$scope.logItem = function() {
console.log($scope.items['some key']); // this works
}
Clicking on the "click me" link logs my item to the console as expected.
Feels like the collection at loaded time isn't fully populated with the underlying items from firebase.
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