问到组合框的WPF数据库

EN

 class Bank
    {
        public string bankcode{get; set;}
        public string bankname { get; set; }    
        public ObservableCollection <BankBranch> branches;

    }
    class BankBranch
    {
        public string branchcode { get; set; }
        public string branchname { get; set; }
    }

            Bank b = new Bank{
                bankcode="1",
                bankname="Bank1",
                branches = new ObservableCollection<BankBranch>(){
                    new BankBranch(){branchcode="11", branchname="Location1"},
                    new BankBranch(){branchcode="11", branchname="Location12"}
                },

            };
            bankpanel.DataContext = b;


<StackPanel x:Name="bankpanel">
        <StackPanel Orientation="Horizontal">
            <TextBlock >Bank Code</TextBlock>
            <TextBox Text="{Binding bankcode}" Width="100"/>
        </StackPanel>
        <StackPanel Orientation="Horizontal">
            <TextBlock >Bank Name</TextBlock>
            <TextBox Text="{Binding bankname}" Width="100"/>
        </StackPanel>
        <StackPanel Orientation="Horizontal">
            <TextBlock >Bank Branches</TextBlock>

            <ComboBox ItemsSource="{Binding branches}" DisplayMemberPath="branchname" 
 SelectedValuePath="branchname" 
 Width="100">

            </ComboBox>
        </StackPanel>
    </StackPanel>