如何使用Caliburn.Micro MVVM在WPF中的同一视图上从另一个视图模型更新list <>？

Question

I'm new to WPF and I want to follow MVVM framework using Caliburn Micro. I have got stuck update a list in a view model from another one.

I have 3 Views:

• POSView : Contains two Content Controls for 2 other Views
• ProductView : List of all products
• CartView : List of all products added in cart

On click of Product in Product View, product should get added in Cart View

POSViewModel.cs

public class POSViewModel : Conductor<object>.Collection.AllActive
    {
        #region Private Variables
        private ProductsViewModel _ProductsViewModel;
        private CartViewModel _CartViewModel;
        #endregion

        #region Public Variables
        public ProductsViewModel ProductsViewModel
        {
            get { return _ProductsViewModel; }
            set { _ProductsViewModel = value; }
        }

        public CartViewModel CartViewModel
        {
            get { return _CartViewModel; }
            set { _CartViewModel = value; }
        }
        #endregion

        #region Public Methods
        public POSViewModel()
        {
            ProductsViewModel = new ProductsViewModel();
            CartViewModel = new CartViewModel();
        }
        #endregion
    }

ProductsViewModel.cs: On AddProdClick(ProductModel productModel), I want to add clicked product to CartView.

public class ProductsViewModel : Conductor<object>
    {
        public BindableCollection<ProductModel> Products { get; set; }
        public ProductsViewModel()
        {
            Products = new BindableCollection<ProductModel>();
            for (int i = 0; i < 25; i++)
            {
                Products.Add(new ProductModel
                {
                    ProductName = "Product" + i.ToString(),
                    Qty = i + 2,
                    Rate = i * 10
                }); ;
            }

        }

        public void AddProdClick(ProductModel productModel)
        {

        }

    }

ProductView.xaml: its a user control having product list. Button with product is bind to AddProdClick in View Model.

 <Button Content="Add To Cart" cal:Message.Attach="AddProdClick($datacontext)" />

CartViewModel.cs

public class CartViewModel : Conductor<object>
    {
        private BindableCollection<ProductModel> _CartProducts;
        public BindableCollection<ProductModel> CartProducts
        {
            get
            {
                return _CartProducts;
            }
            set
            {
                NotifyOfPropertyChange(() => CartProducts);
                _CartProducts = value;
            }
        }

        public CartViewModel()
        {
            CartProducts = new BindableCollection<ProductModel>();
        }
    }

I expect to Add item to Cart.

Answer 1

you could use CartViewModel as Args:

    public POSViewModel()
    {   
        CartViewModel = new CartViewModel();    
        ProductsViewModel = new ProductsViewModel(CartViewModel);
    }

and use it in constuctor of ProductsViewModel

public class ProductsViewModel : Conductor<object>
{
    public BindableCollection<ProductModel> Products { get; set; }
    public CartViewModel CVM { get; set; }
    public ProductsViewModel(CartViewModel CVM)
    {
                    this.CVM = CVM;
    }

    public void AddProdClick(ProductModel productModel)
    {
                    CVM.Add(productModel)
    }
}

you have another solution : using the PosViewModel:

 public POSViewModel()
{   
    CartViewModel = new CartViewModel();    
    ProductsViewModel = new ProductsViewModel(this);
}

public class ProductsViewModel : Conductor<object>
{
    public BindableCollection<ProductModel> Products { get; set; }
    public CartViewModel CVM { get; set; }
    public ProductsViewModel(POSViewModel PVM)
    {
                    this.CVM = PVM.CartViewModel;
    }

    public void AddProdClick(ProductModel productModel)
    {
                    CVM.Add(productModel)
    }
}

A third solution is to use EventAggregator you need to modify some coding

see EventAggregator

When you click, you do EventAggregator.publish(new Addevent) in the Add method

and in PosviewModel you catch the event...

but for that you have to modify some lines of code, but read the link its not complex