wpf combobox binding

Question

Hi I´m trying to bind a List<> to a combobox.

<ComboBox Margin="131,242,275,33" x:Name="customer" Width="194" Height="25"/>

public OfferEditPage()
    {
        InitializeComponent();
        cusmo = new CustomerViewModel();
        DataContext = this;
        Cusco = cusmo.Customer.ToList<Customer>();
        customer.ItemsSource = Cusco;
        customer.DisplayMemberPath = "name";
        customer.SelectedValuePath = "customerID";
        customer.SelectedValue = "1";
    }

I become no Error but the Combobox is always empty. Cusco is the Property of my List. I have no idea whats wrong with this code. Can you help me?

Greets

 public class Customer
{
    public int customerID { get; set; }
    public string name { get; set; }
    public string surname { get; set; }
    public string telnr { get; set; }
    public string email { get; set; }
    public string adress { get; set; }
}

this is the Customer Class which is my model.

public class CustomerViewModel
{
    private ObservableCollection<Customer> _customer;

    public ObservableCollection<Customer> Customer
    {
        get { return _customer; }
        set { _customer = value; }
    }

    public CustomerViewModel()
    {
        GetCustomerCollection();
    }

    private void GetCustomerCollection()
    {
        Customer = new ObservableCollection<Customer>(BusinessLayer.getCustomerDataSet());
    }

}

and this is the ViewModel.

Solution 1

Try setting the ItemsSource property with an actual Binding object

XAML Method (recommended):

<ComboBox
    ItemsSource="{Binding Customer}"
    SelectedValue="{Binding someViewModelProperty}"
    DisplayMemberPath="name"
    SelectedValuePath="customerID"/>

Programmatic method:

Binding myBinding = new Binding("Name");
myBinding.Source = cusmo.Customer; // data source from your example

customer.DisplayMemberPath = "name";
customer.SelectedValuePath = "customerID";
customer.SetBinding(ComboBox.ItemsSourceProperty, myBinding);

Also, the setter on your Customer property should raise the PropertyChanged event

public ObservableCollection<Customer> Customer
{
    get { return _customer; }
    set
    {
        _customer = value;
        RaisePropertyChanged("Customer");
    }
}

If the above does not work, try moving the binding portion from the constructor to the OnLoaded override method. When the page loads, it may be resetting your values.

Solution 2

As an expansion on Steve's answer,

You need to set the datacontext of your form.

Currently you have this:

InitializeComponent();
cusmo = new CustomerViewModel();
DataContext = this;

It should be changed to this:

InitializeComponent();
cusmo = new CustomerViewModel();
DataContext = cusmo;

Then as Steve noted you will need another property on the viewmodel to store the selected item.