Getting a particular attribute and adding it to a collection in backbone.js: The solution explained

Question

Getting a particular attribute and adding it to a collection in backbone.js: The solution explained

With the given JSON structure, I am looking to extract a specific attribute and store it in a collection. The data is formatted as follows:

{
   foo: "lorem ipsum",
   bars: [{
       a: "a",
       b: {c: "d", e: "f"}
   }, {
       a: "u",
       b: {w: "x", y: "x"}
   }]
}

I know how to extract only bars (excluding foo bars) with the help of parse, but my goal now is to retrieve bars, locate a specific object based on the a attribute, and then store b inside a collection.

The approach I have in mind involves:

MyCollection = Backbone.Collection.extend({
    model: MyModel,
    url: "someUrl",

    parse: function(data) {
         data.bars.each(function(bar) {
             if (bar.a == i) {
                 return bar.b;
             }
         }
    }
};

var myCollection = new MyCollection();
myCollection.fetch({
     success: function() {
          console.log("Successfully collected the correct 'b' values!");
     }
});

My challenge lies in determining where and how to input the value of i for the condition if(bar.a == i).

javascript json backbone.js

Answer 1

Answer №1

When using the fetch function, any options passed are also forwarded to the Collection.parse method. This allows for customization, as shown in this example:

MyCollection = Backbone.Collection.extend({
    model: MyModel,
    url: "someUrl",

    parse: function(data, opts) {
        console.log(opts);

        // Custom filter logic
        var matches = _.where(data.bars, {a: opts.i});
        return _.map(matches, "b");
    }
});

var myCollection = new MyCollection();

// Specify a filter option when fetching the collection
myCollection.fetch({
    i: "u", 
    success: function() {
        console.log("Filtered collection retrieved successfully!");
    }
}).then(function() {
    console.log(myCollection.toJSON());        
});

You can view a demo of this code in action here.

Answer 2

When using the fetch function, any options passed are also forwarded to the Collection.parse method. This allows for customization, as shown in this example:

MyCollection = Backbone.Collection.extend({
    model: MyModel,
    url: "someUrl",

    parse: function(data, opts) {
        console.log(opts);

        // Custom filter logic
        var matches = _.where(data.bars, {a: opts.i});
        return _.map(matches, "b");
    }
});

var myCollection = new MyCollection();

// Specify a filter option when fetching the collection
myCollection.fetch({
    i: "u", 
    success: function() {
        console.log("Filtered collection retrieved successfully!");
    }
}).then(function() {
    console.log(myCollection.toJSON());        
});

You can view a demo of this code in action here.

Getting a particular attribute and adding it to a collection in backbone.js: The solution explained

Answer №1

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