Knockout copying observable array issue

Question

I am trying to copy one observably array to another observable array. I have a form that has a billing address, shipping address and checkbox that when clicked allows the user to copy all of their shipping info to their billing address. The problem I am having is when I copy one observable array to another, then any time I make a change to either observable both observable arrays get updated. I would like to keep both observable array values seperate just copy the values from one to the other.

My observable arrays are set up using the mapping plugin:

self.billingAddress = ko.mapping.fromJS(InitialEmptyAddressModel);
self.shippingAddress = ko.mapping.fromJS(InitialEmptyAddressModel);

Then to copy shipping info to billing after entering shipping information and clicking on 'Use Shipping Address':

 self.CopyAddress = function() {
    self.billingAddress(self.shippingAddress());
    }

I've also tried the following: What is the best way of cloning/copying an observablearray in knockoutJS?

Any help would be appreciated thank you.

RP Niemeyer · Accepted Answer · 2012-10-10T18:03:56.513

2

You don't really want to copy over the observables that are inside shippingAddress. You would likely want to get a clean version of it and then apply it to the other mapped object.

Something like:

self.copyAddress = function() {
    var clean = ko.mapping.toJS(self.shippingAddress);
    ko.mapping.fromJS(clean, self.billingAddress);
};

Sample: http://jsfiddle.net/rniemeyer/NdS5M/

edited Oct 10 '12 at 18:03

answered Oct 10 '12 at 17:58

RP Niemeyer

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Thanks for the quick response this worked. Why did your original answer not work, just curious? – GPB Oct 10 '12 at 18:23
I didn't test the first answer, because github was briefly down so the mapping plugin wasn't loading in jsFiddle. When you have an object and send it through the mapping plugin, the root will not be observable, so you would not have to be able to treat it as an observable (for arrays it does create an observableArray). So, since we would not be replacing an entire observable with a new one, then we need to update the existing observable's values, since they are already bound in the UI. Hope that makes sense. – RP Niemeyer Oct 10 '12 at 19:20

Knockout copying observable array issue

1 Answers1