Firebase-按列过滤 [英] Firebase - Filter by a column

问题描述

我正在为我的Angular.js应用程序使用Firebase.

I'm using Firebase for my Angular.js application.

我正在寻找与Firebase相同的SQL WHERE语句.

I'm looking for the equivalent of SQL's WHERE statement for Firebase.

我在Firebase中存储了一系列电视连续剧，我只想获取那些具有用户输入名称的电视连续剧(在示例searchQuery中).

I have an array of TV series stored in Firebase, and I want to fetch only these that has the name that the user entered (in the example searchQuery).

Firebase支持吗?它有这样的东西吗?

Does Firebase support it? Does it have something like this?

var seriesRef = new Firebase('http://{app}.firebaseio.com/series');
var seriesObject = $firebaseObject(seriesRef.query({ name: searchQuery }));

推荐答案

我有一些建议可能对您有帮助:

I have some suggestions that may help here:

• 查看 Firebase查询文档.具体来说，
  • .orderByChild()
  • .equalTo()
  • Check out the Firebase Query documentation. Specifically,
    • .orderByChild()
    • .equalTo()
    • 查看此有效的 PLNKR示例 .
      • 我在一个公共Firebase实例中复制了您的数据.
      • 您要查找的查询是seriesCollectionRef.orderByChild("name").equalTo(seriesName)
      • 如果在输入中输入"Avatar: The Last Airbender"并单击查找"，则将获得匹配的系列对象.
      • Check out this working PLNKR example.
        • I replicated your data in one of my public Firebase instances.
        • The query that you're looking for is seriesCollectionRef.orderByChild("name").equalTo(seriesName)
        • If you enter 'Avatar: The Last Airbender' in the input and click "Find", you'll get the matching series object.
        • 请参阅扩展AngularFire的文档服务.
        • 您可以在不扩展服务的情况下完成同样的事情，请参阅最后的代码片段.

        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;
            }
          });
        });
        

        控制器

        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，这就是控制器功能的样子:

        Without Extended Service

        Here is what a controller function would look like if you weren't using the factories:

          $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:请注意，您应该在Firebase规则中添加".indexOn":"name"，以便查询有效运行，这一点很重要.像这样:

        Rules

        Note: It's important to note that you should add ".indexOn":"name" to your Firebase rules so that the query runs efficiently. Like so:

        • 请参阅Firebase的为您的数据编制索引部分安全&规则指南.

          "yourfirebaseapp": {
            ".read": "...",
            ".write": "...",
            "series": {
              ".indexOn": "name"
            }
          }
        

        这篇关于Firebase-按列过滤的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！