Retrieving JSON data using Backbone.js fetch() and translating it into a model results in get()

Question

Retrieving JSON data using Backbone.js fetch() and translating it into a model results in get()

My current issue involves fetching a JSON file and storing it in a model for later access. However, I am encountering difficulties when trying to access the attributes through the get() method as it keeps returning undefined. The JSON file contains an array of games which are objects with various attributes. My main goal is to save them in the model and retrieve them. Here's what I have attempted so far:

var player = Backbone.Model.extend({
   initialize: function(app, options) {
      this.app = app;
      var _this = this;

      this.fetch({
         url: "someurl",
         success: function() {
            console.log("success");
         }
      });
   }
});

var instplayer = new player();
instplayer.on('change', function(){
   console.log(model);
   console.log(model.get(games));
})

I believe that there should be an event trigger to ensure that get() is called only when the data has fully loaded. Despite my attempts, I still receive undefined. What steps do I need to take to resolve this issue?

javascript json backbone.js model

Answer 1

Answer №1

Imagine you have a JSON structure for your player, as shown below:

{
    "username": "joe",
    "games": [
        {
            "title": "Pacman"
        }, {
            "title": "Super Mario"
        } 
    ]
}

If this was the data format you were dealing with, here is an example of how you could manage and render it using code:

var Game = Backbone.Model.extend({
  defaults: {
    title: ''
  }
});

var Games = Backbone.Collection.extend({
  model: Game
});

var Player = Backbone.Model.extend({
  defaults: {
    username: ''
  },
  url: 'http://www.mocky.io/v2/56261127250000a01accb34f',
  initialize: function(){
    this.games = new Games();
    this.listenTo( this, "sync", this.initGames );
    this.fetch();
  },
  initGames: function(){
    this.games.add( this.get('games') );
    this.trigger('ready', this);
  }
});

var PlayerView = Backbone.View.extend({
  template: _.template('<h1><%=username%></h1> and his games: <ol class="games"></ol>'),
  render: function(){
    this.$el.html( this.template( this.model.toJSON() ) );
    this.model.games.each( this.renderGame, this );
    return this;
  },
  renderGame: function(game, i){
    var gameView = new GameView({ model: game });
    gameView.render().$el.appendTo( this.$('.games') );
  }
});

var GameView = Backbone.View.extend({
  tagName: 'li',
  template: _.template('<strong>Game:</strong> <%=title%gt;'),
  render: function(){
    this.$el.html( this.template( this.model.toJSON() ));
    return this;
  }
});


var dude = new Player();
dude.on('ready', function(player){
  var playerView = new PlayerView({ model: player });
  playerView.render().$el.appendTo( document.body );
});

<script src='http://code.jquery.com/jquery.js'></script>
<script src='http://underscorejs.org/underscore.js'></script>
<script src='http://backbonejs.org/backbone.js'></script>

Answer 2

Imagine you have a JSON structure for your player, as shown below:

{
    "username": "joe",
    "games": [
        {
            "title": "Pacman"
        }, {
            "title": "Super Mario"
        } 
    ]
}

If this was the data format you were dealing with, here is an example of how you could manage and render it using code:

var Game = Backbone.Model.extend({
  defaults: {
    title: ''
  }
});

var Games = Backbone.Collection.extend({
  model: Game
});

var Player = Backbone.Model.extend({
  defaults: {
    username: ''
  },
  url: 'http://www.mocky.io/v2/56261127250000a01accb34f',
  initialize: function(){
    this.games = new Games();
    this.listenTo( this, "sync", this.initGames );
    this.fetch();
  },
  initGames: function(){
    this.games.add( this.get('games') );
    this.trigger('ready', this);
  }
});

var PlayerView = Backbone.View.extend({
  template: _.template('<h1><%=username%></h1> and his games: <ol class="games"></ol>'),
  render: function(){
    this.$el.html( this.template( this.model.toJSON() ) );
    this.model.games.each( this.renderGame, this );
    return this;
  },
  renderGame: function(game, i){
    var gameView = new GameView({ model: game });
    gameView.render().$el.appendTo( this.$('.games') );
  }
});

var GameView = Backbone.View.extend({
  tagName: 'li',
  template: _.template('<strong>Game:</strong> <%=title%gt;'),
  render: function(){
    this.$el.html( this.template( this.model.toJSON() ));
    return this;
  }
});


var dude = new Player();
dude.on('ready', function(player){
  var playerView = new PlayerView({ model: player });
  playerView.render().$el.appendTo( document.body );
});

<script src='http://code.jquery.com/jquery.js'></script>
<script src='http://underscorejs.org/underscore.js'></script>
<script src='http://backbonejs.org/backbone.js'></script>

Answer 3

Answer №2

It's important to ensure there are no typos in your code, especially when passing parameters to functions.

instplayer.on('change', function(){
  console.log(model);
  console.log(model.get(games));
})

Make sure you pass the correct parameters like this:

instplayer.on('change', function(model, options){
  console.log(model);
  console.log(model.get("games"));
})

Also, remember that 'games' should be a string and not a variable.

Additionally, consider what the json data returns and if necessary, override the parse function for accurate results.

If you're fetching an array of objects, it might be better to use a collection of players instead.

Answer 4

It's important to ensure there are no typos in your code, especially when passing parameters to functions.

instplayer.on('change', function(){
  console.log(model);
  console.log(model.get(games));
})

Make sure you pass the correct parameters like this:

instplayer.on('change', function(model, options){
  console.log(model);
  console.log(model.get("games"));
})

Also, remember that 'games' should be a string and not a variable.

Additionally, consider what the json data returns and if necessary, override the parse function for accurate results.

If you're fetching an array of objects, it might be better to use a collection of players instead.

Retrieving JSON data using Backbone.js fetch() and translating it into a model results in get()

Answer №1

Answer №2

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