Explore flat data querying using Firebase and AngularFire

I am working with data stored in firebase, utilizing a flat structure with key-value pairs to establish a many-to-many relationship between events and users (see figure 1). While it's straightforward to look up events associated with a user using pure JavaScript (as shown in figure 2), I am facing challenges when attempting to achieve the same using angularfire and firebaseObject or array. Does anyone have insights on how to execute such a query efficiently?

Figure 1.

{
  users: {
      user_id1: {
         events: {
            event_id1: true,
            event_id2: true
         }
      },
      user_id2: {
         events: {
            event_id3: true,
            event_id4: true
         }
      },
      user_idN...
  },
  events: {
    event_id1: {
        users: {
           user_id1: true
         }
    },
    event_id2: {
        users: {
           user_id1: true
         }
    },
    event_idN...
  }
}

Figure 2

// List all of user_id1's events
var ref = new Firebase("https://<<example>>.firebaseio.com/");
// fetch a list of user_id1's events
ref.child("users/user_id1/events").on('child_added', function(snapshot) {
  // for each event, fetch it and print it
  String groupKey = snapshot.key();
  ref.child("events/" + groupKey).once('value', function(snapshot) {
    console.log(snapshot.val());
  });
});

Answer №1

Using the $extend function in AngularFire can greatly enhance your code.

By sharing the $event_id key, you can load events after retrieving the user.

app.factory("UserFactory", function($firebaseObject) {
  return $firebaseObject.$extend({
      getEvent: function(eventId) {
        var eventRef = new Firebase('<my-firebase-app>/events').child(eventId);
        return $firebaseObject(eventRef);
      }
   });
});

app.controller('MyCtrl', function($scope, UserFactory) {
  var userRef = new Firebase('<my-firebase-app>').child("users/user_id1/");
  var user = new UserFactory();
  $scope.event = user.getEvent(user.events.event_id1);
});

Explore the API reference for additional details.

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