Backbone.js Collection filter top 10 models

Question

my Collection fetches a few records and I have to show only top 10 records from it. I attempted

   this.collection.each(function(){
        if (count == 10) break;
        //pass model to view
   });

unfortunately break does not work with each() API of underscore.js Refer here: how to break the _.each function in underscore.js

How do I write a filter to pluck only top 10 from the collection

     this.collection.filter();

UPDATE: collection.first(10) fetched me filtered list. However, I still needed to chain .each() to this collection to process the collection items. collection.first() does not allow chain. Please refer to my selected answer for solution to this.

possible duplicate of [get only the first 20 items in a backbone collection](http://stackoverflow.com/questions/8240382/get-only-the-first-20-items-in-a-backbone-collection) — mu is too short, Aug 09 '12 at 20:17
@muistooshort I see this is an exact duplicate.Thanks for pointing it out. I have received partial solution to my question. I am amending this question so that I can get help on the rest of it — Vikram, Aug 09 '12 at 20:54

score 7 · Accepted Answer · edited May 23 '17 at 11:48

7

E.g.

this.collection.first(10)

Then, if you need to work with each model, e.g. :

    var collection = new Backbone.Collection([{id:1}, {id:2}, {id:3}, {id:4}, {id:5}],{model: Backbone.Model});

    var newCollection = new Backbone.Collection(collection.first(2));

    newCollection.each(function(model){
      alert(JSON.stringify(model.toJSON()));
    });

See the jsfiddle. Note that there is another way to do it with the Underscore chain method as said in this topic.

Have a look at Backbone doc and Underscore doc.

edited May 23 '17 at 11:48

Community

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answered Aug 09 '12 at 19:52

xiris

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first() in underscore.js is array function and this is a Collection. I tried using it and browser throws up at that very line saying: Object doesnt support this property or method...thanks for your answer! – Vikram Aug 09 '12 at 20:02
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Anyway, it should work for a Collection. There is another topic on stackoverlow : http://stackoverflow.com/questions/8240382/get-only-the-first-20-items-in-a-backbone-collection. A lot of underscore methods also work for Backbone Collection, just removing the first argument (array) and calling the method from the Backbone Collection object. – xiris Aug 09 '12 at 20:12
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I second xiris, take a look at this fiddle (look in the console) http://jsfiddle.net/RgBVw/ – Jens Alm Aug 09 '12 at 20:22
@JensAlm I was trying to do: collection.first(2).each(function(model){ alert(model.toJSON()); }); but it throws me that error: http://jsfiddle.net/RgBVw/3/ – Vikram Aug 09 '12 at 20:42
@xiris thanks...I see from your link that it does not allow chaining.. which is why I am getting that error – Vikram Aug 09 '12 at 20:43
Else, you can use the Underscore chain method (http://documentcloud.github.com/underscore/#chain) as said in the other topic. – xiris Aug 09 '12 at 20:53
@xiris excellent! that works for me...Can you please edit your answer to incorporate the solution you provided in the fiddle. I will mark your solution as answer to my question....thanks for following up! – Vikram Aug 09 '12 at 20:56

Backbone.js Collection filter top 10 models

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