Receive data many-to-many relation Firebase

Question

I have an extended question to this question.

What if the player belong to more than one team?

I have this

json

  "Players" : {
    "-YRHd4IjrjsBXx__B" : {
      "name" : "The best forward",
      "creationDate" : "2016-02-26 15:50:39",
      "teams" : {
         "-KAByPeIz4IjrjsBXx__B" : true,
         "-KEFPuCXcqOah_GJwsMCu" : true,
         "-KEwuQxvGpYTEJ7YQ58-l" : true,
         "-KKF8vPtf8J7cfqFh2PLm" : true
      },
    },
  etc...
  }

players-service.js

getPlayers: function(teamid) {
  var Players = {};
  var teamsIndex = ref.child('teams/' + teamid + '/players/');
  var playersIndex = ref.child('players/');
  teamsIndex.on('child_added', function(snapshot) {
    var playerKey = snapshot.key;
    playersIndex.child(playerKey).on('value', function(playersnap){
      $timeout(function() {
          console.log("key", playerKey);
          players[playerKey] = playersnap.val();
      });
    });
  });
  teamIndex.on('child_removed', function(snapshot) {
    $timeout(function(snapshot) {
      delete players[snapshot.key()];
    });
  });

  return players;
}

But it returns a list of object. I know that I could probably query/change the data structure to/in firebase and return it as a $firebaseArray which I prefer as I use angularfire.

Do you mean that you want getPlayer to return an array instead of an key value object? — Devid Farinelli
– Devid Farinelli, Commented Jun 19, 2016 at 19:12
I'm confused. I'm stuck in between the nosql and SQL worlds. I think i wonder if my solution are the way to go. It could be that need to stick to this solution or denormalize my data more. Haven't diceded yet. A the moment I'm tring to denormalize more. aka put teamid: true in the root of the player node. "Players" : { "-YRHd4IjrjsBXx__B" : { "name" : "The best forward", "creationDate" : "2016-02-26 15:50:39", "-KAByPeIz4IjrjsBXx__B" : true, "-KEFPuCXcqOah_GJwsMCu" : true, } } — Peter Sandström
– Peter Sandström, Commented Jun 19, 2016 at 19:49

Devid Farinelli · Accepted Answer · 2016-06-20 08:25:19Z

2

You usually structure your data depending on how you want to retrieve them.

From my understanding (correct me if I'm wrong) you want to get all the players in a team. For this purpose I would use this structure:

"Players": {
  "player1": {...},
  "player2": {...},
  "player3": {...}
},
"Teams': {
  "team1": {...},
  "team2": {...}
},
"TeamPlayers" : {
  "team1": {
    "player1": true,
    "player2": true
  },
  "team2": {
    "player1": true,
    "player3": true
  }
}

Or using an array

"TeamPlayers" : {
  "team1": [
    0: "player1",
    1: "player2"
  ]
}

edited Jun 20, 2016 at 8:25

answered Jun 19, 2016 at 20:55

Devid Farinelli

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5 Comments

Peter Sandström Over a year ago

I love you! seriously I do!

Devid Farinelli Over a year ago

Ahah happy to help! Thanks for upvoting. I've edited with another solution

Peter Sandström Over a year ago

This phrase made it to me: "You usually structure your data depending on how you want to retrieve them."

Lucas E. Saavedra Over a year ago

how can I show a list of all player1's teams. do I have to do many queries?

Devid Farinelli Over a year ago

In this case I would use somethings likeref("TeamPlayers").orderByChild("player1").startAt(true). I'm not sure this is the right code but it is the correct approach

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