How can I set default selects in multiple select with foreach binding

[h...@homemaster.co.kr]

Hello I'm trying to make default selected  multiple binding in for loop

I have following situation. 

company have  productList and managerList 

each  manager has their own  prefered_products with in company's product list. 

I want to  show this data in table. I want to make show prefered_product of manager and other products of company  

html file

 <tbody data-bind="foreach: Managers">

      <tr >       

        <td class="col-xs-2">

                                <select type="text" data-bind="options:$parent.productList,optionsText:'name', selectedOptions:prefered_products'" class="form-control" ></select>

       </td>

 </tr>

js file

var products = [ {name: 'product1', _id : 'abc'},{name: 'product2', _id : 'def'},{name: 'product3', _id : 'ghi'}]

var managers = [ {_id : 'mand', name: 'kate', prefered_products: [{name: 'product2', _id : 'def'},{name: 'product3', _id : 'ghi'}] },

                            {_id : 'todhm', name: 'jordan', prefered_products: [{name: 'product1', _id : 'abc'},{name: 'product2', _id : 'def'}]}]

var ManagerData =function(data){

        var self = this

        self.id = ko.observable(data._id);

        self.name = ko.observable(data.name);

        self.prefered_products = ko.observableArray([]);

        self.add_product = function(product){

                self.prefered_products.push(new Product(product));

        }

        for(i=0; i< data.prefered_products.length;i++){

            self.add_product(data.prefered_products[i]);

        }

}

var ProductType = function(data){

        var self = this;

        self.name = ko.observable(data.name);

        self._id = ko.observable(data._id);

}

var ViewModel = function(){

       self.productList = ko.observableArray([]);

       self.managerList = ko.observableArray([]);

}

var ViewModel = new ViewModel();

 ko.applyBindings(ViewModel);

 products.forEach(function(product,index){

                           ViewModel.productList.push(new Product(product));

                       })

managers.forEach(function(manager,indexdo){

                          ViewModel.ManagerList.push(new ManagerData(manager));

                                     }

[noirabys]

hi,
the context is based on the object you supply with applyBindings.

there is neither a Managers object in your viewmodel nor a global variable.

-> foreach: managerList 

best regards,

 noirabys