Sum values in nested knockout observableArray

Question

I Want to sum the nested Element QtyToOrder * VendorPrice For all the array elements based on the selected vendor.

My nested observable array that looks like this:

CheckStock: [{
        ItemName: "123",
        Vendors: [{
                         QtyToOrder: "5",
                         VendorPrice: "1243"}],
        SelectedVendor: 0
       },{
        ItemName: "123",
        Vendors: [{
                         QtyToOrder: "5",
                         VendorPrice: "1243"},
                   {
                         QtyToorder: 9
                         VendorPrice: 999 }],
        SelectedVendor: 0
       }]

I have created a Fiddle with my actual data that I use and the ViewModel that I am using. and this function:

 MyDataViewModel.TotalPurchaseReqPrice = ko.computed(function () {
        var self = MyDataViewModel;
        var tot;
        for (var i = 0; i < self.CheckStock().length; i++) {
            for (var j = 0; j < self.CheckStock()[i].SelectedVendor() ; j++) {
                var HasVal = self.CheckStock()[i].SelectedVendor()[j] ? (ko.toJS(SelectedVendor().QtyToOrder) * ko.toJS(SelectedVendor().VendorPrice)) : 0
                tot += HasVal
            }
        }
        return tot;
    });

To try and get it to work, but I do not get any value returned from my Viewmodel. I have also tried Subscribing to the SelectedVendor but keep getting that the SelectedVendor is undefined. Any Assistance would be greatly appreciated

margabit · Accepted Answer · 2013-09-12 12:09:56Z

Ok.. It got me a while to make this work, but I think I achieved what you wanted to do.

The main problem is that you are creating this property:

 MyDataViewModel.TotalPurchaseReqPrice = ko.computed(function () {}

But this never knows when it should be computed. In fact the properties that should trigger the change are not in the MyDataViewModel, they are in each of the CheckStock objects. I guess you want to trigger the recalculation when any of the dropdown changes, so this belongs to the property SelectedVendor of the objects of CheckStock.

So instead, we can do the following:

           var stock = {
                    ProductName: element.ProductName,
                    RequiredComponents: element.RequiredComponents,
                    StockCode: element.StockCode,
                    RequiredQtyByBom: element.RequiredQtyByBom,
                    QtyUnassignedInWarehouse: element.QtyUnassignedInWarehouse,
                    QtyAllocatedInWarehouse: element.QtyAllocatedInWarehouse,
                    PCBReference: element.PCBReference,
                    QtyOnOrder: element.QtyOnOrder,
                    SelectedVendor: ko.observable(0),
                    Vendors: ko.mapping.fromJS(element.Vendors),
                    RequireVendor: element.RequireVendor
                };

                stock.SelectedVendor.subscribe(subscription, MyDataViewModel);
                MyDataViewModel.CheckStock.push(stock);

Notice that in the subscribe function I'm passing the delagate to trigger and MyDataViewModel as the context. The subscription variable is the function to calculate the TotalPurchaseReqPrice. I made some changes here, maybe this function is not doing exacly what you wanted to do.. I did some interpretation :)

  var subscription = function () {
        var tot = 0;
        for (var i = 0; i < this.CheckStock().length; i++) {
            if(this.CheckStock()[i].SelectedVendor()){
                   tot += this.CheckStock()[i].SelectedVendor().QtyToOrder() * this.CheckStock()[i].SelectedVendor().VendorPrice();
            }            
        }
        this.TotalPurchaseReqPrice(tot);
    };

I changed quite a lot of code, so better if you take a look at this JsFiddle.

I hope this is more or less what you wanted to achieve.

YOU SIR, ARE A GENTLEMEN AND A SCHOLAR!!!! have been struggling with this for 2 days with no luck

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