我在使用AngularFire / Firebase从集合中获取单个记录时遇到了一些麻烦(然后,在我拥有它之后,从集合中删除它)。我相信我正在遵循此处的正确文档:https://www.firebase.com/docs/web/libraries/angular/api.html#angularfire-firebasearray
注意:我发现很多文档/博客/答案似乎都使用了弃用的$ firebase服务(使用$ asArray方法) - 但是,更新的文档确定$ firebaseArray是正确使用的服务,FYI。
出于某种原因,即使我可以准确地提取我的民意调查集合,我也无法提取单个元素(尽管官方文档看起来与我正在使用的语法相同)。
$ remove文件(https://www.firebase.com/docs/web/libraries/angular/api.html#angularfire-firebasearray-removerecordorindex):
## official docs ##
$remove(recordOrIndex)
Remove a record from Firebase and from the local data. This method returns
a promise that resolves after the record is deleted at the server. It will
contain a Firebase reference to the deleted record. It accepts either an
array index or a reference to an item that exists in the array.
var list = $firebaseArray(ref);
var item = list[2];
list.$remove(item).then(function(ref) {
ref.key() === item.$id; // true
});
我的代码(请参阅下面的console.log):
.service('pollsData', function($firebaseArray){
var fireRef = new Firebase('<-my-firebase-ref-url>');
var polls = $firebaseArray(fireRef.child('polls'));
var service = this;
this.clearPolls = clearPolls;
this.setInitialPolls = setInitialPolls;
this.getPolls = getPolls;
function clearPolls() {
console.log("length: ", polls.length); <--- I get a length of 0
console.log(polls); <-- I get a $firebaseArray object including the methods in the API docs
console.log(polls[0], polls[1], polls[2]); <--- all 3 are undefined even though I can see several in the firebase data dashboard
var poll = polls[1];
console.log("poll?: ", poll);
polls.$remove(poll);
}
function getPolls() {
polls = polls || $firebaseArray(fireRef.child('polls'));
return polls; <-- I can successfully ng-repeat over this returned selection in the template
}
function setInitialPolls() {
service.clearPolls();
polls.$add({
one: {
name: "fantastic pollllllls",
selection_one: {
name: "pizza",
count: 0
},
selection_two: {
name: "fries",
count: 0
}
},
two: {
name: "mediocre poll",
selection_one: {
name: "blue",
count: 0
},
selection_two: {
name: "green",
count: 0
}
}
});
}
setInitialPolls();
});
有关为什么括号[]符号从$ firebaseArray中取出记录的任何见解都无法按照AngularFire文档的预期工作?
更新:提供的回复仍然有用,因为这似乎与我对$ firebaseArray的新文档的理解以及API文档中$ remove部分的示例相冲突。了解这仍然是一个异步问题,但由于$ firebase服务已被弃用,而且我引用了更新的文档,因此需要更新此问题/解决方案。
答案 0 :(得分:2)
有三种方法可以从$firebaseArray
对象中检索记录。
$getRecord(key)
$keyAt(recordOrIndex)
$indexFor(key)
我会更仔细地查看每个文档,但是根据您的描述,您可能希望使用$keyAt
。但请记住,$firebaseArray
不是一个严格的数组,并且可用的方法提供的选项/灵活性比您在“只是一个数组”中所用的方法更多。
此外,正如评论中所提到的,您希望在promise方法内部处理三方数据绑定。
var arrayRef = new Firebase(firebase_location).child(child_location);
var theList = $firebase(arrayRef).$asArray();
theList.$loaded(function (list) {
var x = list.$keyAt(list[target_position]);
//use other methods for the $firebaseArray object
});