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angularjs – 使用查询检索记录,AngularFire，
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我正在使用Firebase,Backend-as-a-Service,用于我的网站应用程序,由AngularJS编程.
我想使用db查询来获取记录,例如：WHERE name ==’The Legend Of Korra’
我在Firebase服务器中有一系列电视剧,JSON代码：
{
"series" : {
"-JkqSvwyDw5F9DvGUu6b" : {
"createdAt" : 1426842959884,"creators" : "Michael Dante DiMartino,Bryan Konietzko","description" : "The series follows the adventures of protagonist twelve-year-old Aang and his friends,who must bring peace and unity to the world by ending the Fire Lord's war against the other three nations.","episode_reset" : true,"genres" : "Action,Adventure,Fantasy,Comedy-drama","keywords" : "avatar,the last airbender","name" : "Avatar: The Last Airbender","official_website" : "http://nicktoons.nick.com/shows/avatar","publish_date" : "2005-02-21","updatedAt" : 1426843055127
}
}
}
我正在使用的代码使这个工作：
$scope.isSeriesValid = function(seriesName) {
var seriesRef = new Firebase('http://<<firebaseapp>>.firebaseio.com/series');
var seriesCollection = $firebaseArray(seriesRef);
seriesCollection.$loaded(function() {
angular.forEach(seriesCollection,function(seriesObject,index) {
if(seriesObject.name == seriesName)
return true;
});
});
return false;
};
我想在不使用$firebaseArray和forEach的情况下完成这项工作.我该怎么做？
就像这样：
var seriesRef = new Firebase('http://<<firebaseapp>>.firebaseio.com/series');
var seriesObject = $firebaSEObject(seriesRef.query({ name: seriesName }));
@H_
301_18@
我有一些建议可能会有所帮助：
>查看Firebase Query documentation.具体来说,
> .orderByChild()
> .equalTo()
>您可以将查询与.$ref()结合使用以获取所需的记录.
例
>看看这个工作PLNKR example.
>我在我的一个公共Firebase实例中复制了您的数据.
>您正在寻找的查询是seriesCollectionRef.orderByChild(“name”).equalTo(seriesName)
>如果您在输入中输入“Avatar：The Last Airbender”并单击“Find”,您将获得匹配的系列对象.
>在我的示例中,我扩展了$firebaseArray服务,以包含一个按名称查找特定系列的方法.
>请参阅extending AngularFire services的文档.
>您可以在不扩展服务的情况下完成相同的操作,请参阅上一个代码段.
工厂
app.factory('SeriesFactory',function(SeriesArrayFactory,fbUrl){
return function(){
var ref = new Firebase(fbUrl+'/series');
return new SeriesArrayFactory(ref);
}
});
app.factory('SeriesArrayFactory',function($firebaseArray,$q){
return $firebaseArray.$extend({
findSeries:function(seriesName){
var deferred = $q.defer();
// query by 'name'
this.$ref().orderByChild("name").equalTo(seriesName).once("value",function(dataSnapshot){
if(dataSnapshot.exists()){
deferred.resolve(dataSnapshot.val());
} else {
deferred.reject("Not found.");
}
});
return deferred.promise;
}
});
});
调节器
app.controller('HomeController',function($scope,SeriesFactory,fbUrl) {
$scope.seriesName = '';
$scope.findSeries = function() {
console.log("Finding series with name:'",$scope.seriesName,"'");
var seriesCollection = new SeriesFactory();
seriesCollection.findSeries($scope.seriesName).then(function(data){
console.log("Found",data);
$scope.series = data;
}).catch(function(error){
console.warn(error);
});
};
});
没有扩展服务
如果您不使用工厂,这是控制器功能的样子：
$scope.findSeriesWithoutFactory = function() {
var seriesRef = new Firebase(fbUrl+'/series');
var seriesCollection = $firebaseArray(seriesRef);
seriesCollection.$ref().orderByChild("name").equalTo($scope.seriesName).once("value",function(dataSnapshot){
var series = dataSnapshot.val();
if(dataSnapshot.exists()){
console.log("Found",series);
$scope.series = series;
} else {
console.warn("Not found.");
}
});
};
规则
注意：请务必注意,您应在Firebase规则中添加“.indexOn”：“name”,以便查询有效运行.像这样：
>请参阅Firebase Security & Rules Guide的Indexing Your Data部分.
"yourfirebaseapp": {
".read": "...",".write": "...","series": {
".indexOn": "name"
}
}
希望有所帮助！
