How to change default model attributes using set method in Backbone.js

Question

I have some defults data in Model

window.AppState = Backbone.Model.extend({
  defaults: function() {
    return {
      country:  false,
      region: false
    };
  }
});

var appState = new AppState();

Then in Router I get array with new values for model like this:

[["country", "new country value"], ["region", "new region value"]]

And now in a for loop i cycle to update all received params... I realize it this way

appState.attributes[arg] = val;

but I think it's not clear, because in documentation of Backbone.js I read about "attribute" method and see this: "Please use set to update the attributes instead of modifying them directly." So my questions is: How i can change attributes of defaults using set method?

Sander · Accepted Answer · 2011-11-23 19:56:26Z

9

try the .set() function...

appState.set({arg : val});

once you set the arguments using .set() it will override the default for that.

your example modified a bit:

window.AppState = Backbone.Model.extend({
  defaults: function() {
    return {
      country:  false,
      region: false
    };
  }
});

var appState = new AppState();

// when you get your array of new values you can turn it in an object
var myArray = [["country", "new country value"], ["region", "new region value"]];
var newValues = {};
for (var i = 0; i < myArray.length; ++i)
{
    newValues[myArray[i][0]] = myArray[i][1];
}

// set the properties to the new values
appState.set(newValues);

// if you now return the json of the model, it has changed properties
console.log(appState.toJSON());

remark this for loop depends a lot on the structure of your array, the way i wrote it will work for the array you gave in your example, should anything change to that you will need to change the working of the for loop

remark 2 if you use this technique more often, you could always extract that functionality in a helper method.

edited Nov 23, 2011 at 19:56

answered Nov 23, 2011 at 15:40

Sander

13.4k15 gold badges75 silver badges98 bronze badges

Sign up to request clarification or add additional context in comments.

4 Comments

Bobbe Over a year ago

Yes, that is logic, but my question is, how to make in in cycle: I mean if i have string with key and string with value, how i can make it using .set()? For ex. this code not work: var key = 'country', value = 'some value'; model.set({key, value});

Sander Over a year ago

i changed my answer with what you need to insert the changes. actually they are set as one object, you don't need to loop and set, but you do need a loop to create the object :s

maxl0rd Over a year ago

var attrs = {}; attrs[key] = value; model.set(attrs);

Bobbe Over a year ago

Yes thats true =) Big thanks for you Sander and maxl0rd That is what I mean, now it works perfect.

Collectives™ on Stack Overflow

How to change default model attributes using set method in Backbone.js

1 Answer 1

4 Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

1 Answer 1

4 Comments

Your Answer

Sign up or log in

Post as a guest

Related