WPF组合框数据绑定到自定义对象和datatable.showing System.Data.DataRowView在下拉列表项中

我发布了一个类似的问题 here

<Window xmlns:data="clr-namespace:Myproject">

<Window.Resources>
  <data:UserLogin x:Key="user"></data:UserLogin>
  <DataTemplate x:Key="comboTemplate">
        <TextBlock Text="{Binding Path=username}" />
  </DataTemplate>
</Window.Resources>
<ComboBox Margin="18,121,24,0" Name="cmbEmail" Tag="email" TabIndex="1" ToolTip="enter the email you signed up with here" IsEditable="True" IsSynchronizedWithCurrentItem="True" ItemTemplate="{StaticResource comboTemplate}"  ItemsSource="{Binding}" Height="23" VerticalAlignment="Top" Style="{DynamicResource cmbBoxerrors}">
            <ComboBox.Text>
                <Binding Path="Loginname" Source="{StaticResource user}" ValidatesOnDataErrors="True" UpdateSourceTrigger="PropertyChanged">
                    <Binding.ValidationRules>
                        <ExceptionValidationRule/>
                    </Binding.ValidationRules>
                </Binding>
            </ComboBox.Text>       
 </ComboBox>
</Window>

而xaml.cs是

           if (con != null)
            {
                if (con.State == ConnectionState.Closed)
                    con.Open();

                SqlCeCommand cmdusers = new SqlCeCommand("select * from users order by id", con);

                SqlCeDataAdapter da = new SqlCeDataAdapter(cmdusers);
                userdt = new DataTable("users");
                da.Fill(userdt);

                cmbEmail.DataContext = userdt;

             }  

 class UserLogin :IDataErrorInfo
{
    private string _loginname = "";
    private string _password;


    public string this[string columnName]
    {
        get 
        {  


            string result = null;
            if(columnName == "Loginname")
            {
                if(string.IsNullOrEmpty(this._loginname))
                {
                    result = "Login Name cannot be Empty";
                }
            }

            if (columnName == "Loginname")
            {
                if(!Util.ValidateRegexPatern(Properties.Resources.emailRegex,this._loginname))
                {
                    result = "MalFormed Email address. Please write a correct email addess";
                }
            }

            return result;
        }
    }

    public string Error
    {
        get { return null; }
    }

    public string Password
    {
        get { return _password; }
        set { _password = value; }
    }

    public string Loginname
    {
        get { return _loginname; }
        set { _loginname = value; }
    }
}

ItemTemplate 所选项目显示 System.Data.DataRowView 普通项 具有 DisplayMemberPath 这是相反的行为,因为在选定的项目是正确的,下拉列表项目显示 。使用它们都会引发一个异常,因为我无法同时使用它们来正确显示选定项和下拉列表项。

我真的不知道我做得不对。谁能告诉我一些事情我会非常感激的。谢谢你读这篇文章