javascript - Underscore pluck not working on array of models? - Stack Overflow

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var currentVideos = this.get('items').pluck('video');

//  TODO: Why does pluck not work here?
var currentVideosDurations = _.map(currentVideos, function (currentVideo) {
    return currentVideo.get('duration');
});

var test = _.pluck(currentVideos, 'duration');
console.log("Test:", test);

I was wondering why my second pluck doesn't work, but my map works fine? I thought these were equivilant usages.

Here's a screenshot of a console log showing this.get('items') and the array of currentVideos.

var currentVideos = this.get('items').pluck('video');

//  TODO: Why does pluck not work here?
var currentVideosDurations = _.map(currentVideos, function (currentVideo) {
    return currentVideo.get('duration');
});

var test = _.pluck(currentVideos, 'duration');
console.log("Test:", test);

I was wondering why my second pluck doesn't work, but my map works fine? I thought these were equivilant usages.

Here's a screenshot of a console log showing this.get('items') and the array of currentVideos.

• javascript
• backbone.js
• underscore.js

Share Follow edited Aug 14, 2013 at 17:17 Sean Anderson asked Aug 14, 2013 at 16:56 Sean AndersonSean Anderson 29.4k3333 gold badges132132 silver badges242242 bronze badges 2

• 1 Can you also post a list of sample collection for this problem – Sushanth -- Commented Aug 14, 2013 at 17:02
• Yeah one moment. I've uploaded a screenshot. – Sean Anderson Commented Aug 14, 2013 at 17:14

Add a ment  | 

2 Answers 2

Sorted by: Reset to default 7

The backbone model object doesn't store the properties you get from the model at the top level javascript object. The currentVideo backbone model object actually stores the attributes deeper within the javascript object, in (currentVideo.attributes).

_.pluck(currentVideos, 'duration') checks for the top level attribute (e.g. currentVideo['duration']), which doesn't exist.

The distinction is that Backbone Model objects are more sophisticated than basic javascript objects and don't get attributes by just retrieving object['attrName'].

I thought these were equivilant usages.

Nope. pluck is accessing properties with that name, but get is a method invocation. However, to shorten the map you can use invoke:

var currentVideosDurations = _.invoke(currentVideos, "get", "duration");

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