更新映射的基因剔除对象的子部分

Question

I know this question sounds familiar, but I have read so many of the similar questions and have not been able to find my specific situation.

I have a javascript object called gds (GlobalDataStructure). As its name suggests, this object contains all the information I need for all the web pages of my project and is stored in localStorage (hence why I am not just updating view model and need to map in the first place). It contains all sorts of feeds that are read via AJAX.

I use a constructor function to create gds. To massively simplify this structure and hopefully make this question simple, let's say gds was

function gdStructure(){
    this.lastUpdate = new Date(2010,1,1);
    this.family = new Object();
    this.series = new Object();
    this.product = new Object();
}

so I have

gds= new gdStructure();

then once i have populated the js array with data from initial feeds, I do the following.

    viewmodel = ko.mapping.fromJS(gds);
    ko.mapping.fromJS(gds,viewmodel);

The view model is then bound to each page with

ko.applyBindings(viewmodel);

So this all works no problem. This issue arises when I, for example, get a new family feed and I want to update that object. I can do the following

gds.family=feed;
ko.mapping.fromJS(gds,viewmodel);

And all would work fine, but that is mapping a MASSIVE JS object every time. This is extremely slow so I need to find a way where I can update just the feed that has changed. ideally something like..

ko.mapping.fromJS(gds.family, viewmodel.family);

But this appears not to work. Also because it is an OBJECT I can't just do.

viewmodel.family(gds.family)

Can anybody help me? I am sure this must be so simple.

Thanks in anticipation.

Answer 1

I think you have missunderstood how the lib works, this part looks very strange

viewmodel = ko.mapping.fromJS(gds);
ko.mapping.fromJS(gds,viewmodel);

Your using the definition as data?

Anyway, I use ko.mapping like this (A bit simplified but i think you get the point)

http://jsfiddle.net/QtyGd/1/