How to set datacontext user control

Question

I am writing an application in WPF using MVVm toolkit and have problems connecting viewmodel and view.

The model is created using the ado.net entity infrastructure.

View Model:

public class CustomerViewModel
    {
        private Models.Customer customer;
        //constructor
        private ObservableCollection<Models.Customer> _customer = new ObservableCollection<Models.Customer>();
        public ObservableCollection<Models.Customer> AllCustomers
        {
            get { return _customer; }

        }
        private Models.Customer _selectedItem;
        public Models.Customer SelectedItem
        {
            get { return _selectedItem; }

        }
        public void LoadCustomers()
        {
            List<Models.Customer> list = DataAccessLayer.getcustomers();
            foreach (Models.Customer customer in list)
            {
                this._customer.Add(customer);
            }
            }
        }

And the view (no code at the moment):

<UserControl x:Class="Customers.Customer"
             xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
             xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
             xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006" 
             xmlns:d="http://schemas.microsoft.com/expression/blend/2008" 
             mc:Ignorable="d" 
             xmlns:vm ="clr-namespace:Customers.ViewModels"
             d:DesignHeight="300" d:DesignWidth="300"
             xmlns:toolkit="http://schemas.microsoft.com/wpf/2008/toolkit" >

    <Grid>
        <toolkit:DataGrid ItemsSource="{Binding AllCustomers}" SelectedItem="{Binding SelectedItem, Mode=TwoWay}" AutoGenerateColumns="True">

        </toolkit:DataGrid>

        <toolkit:DataGrid ItemsSource="{Binding SelectedItem.Orders}">

        </toolkit:DataGrid>



    </Grid>
</UserControl>

And the dataaccesslayer class:

 class DataAccessLayer
    {
        public List<Customer> customers = new List<Customer>();

        public static List<Customer> getcustomers()
        {
            entities db = new entities();

            var customers = from c in db.Customer.Include("Orders")
                           select c;
            return customers.ToList();
        }


    }

The problem is that the data is not displayed simply because the data context is not defined. I tried to do this in code, but that didn't work. In any case, I would prefer to do this in the xaml file. Another issue is with SelectedItem bindings - the code is never used.

Answer 1

MVVM, ViewModel . View/ViewModels :

• View is instanced
• ViewModel
• ViewModel
• ViewModel ( )
• ViewModel OnPropertyChanged (""), , - ;

My ViewModel XAML (, VB.NET, # , ):

Public Sub New()
    MyBase.New()
    Me.DataContext = New EditShipmentViewModel(Me) 'pass the view in to set as a View variable
    Me.InitializeComponent()
End Sub

-

<UserControl>
    <UserControl.DataContext>
        <Local:EditShipmentViewModel>
    </UserControl.DataContext>
</UserControl>

, .

, .

Answer 2

, ?

Answer 3

my viewmodel datacontext , Blend4 to. , viewmodel MainViewModel, , :

 <UserControl.Resources>
    <local:MainViewModel x:Key="MainViewModelDataSource" />
 </UserControl.Resources>

 <Grid x:Name="LayoutRoot" DataContext="{Binding Source={StaticResource MainViewModelDataSource}}">
    ...view xaml stuff

 </Grid>

, , , :

  if (!DesignerProperties.GetIsInDesignMode(new DependencyObject()))
        {
             myCollection = new ObservableCollection<Blah>(something);
        }

/Blend 4 , . , , , .

:)