MVVM WPF 数据绑定问题

Question

我是 MVVM 和 WPF 的新手，我有以下模型，我想使用数据绑定向用户展示它（下面还提供了 viewmodel 和 xaml 的代码）。但我不确定缺少什么，因为用户列表根本没有显示在 UI 上。谁能告诉我我的代码中缺少哪些？！

如果不是用户类，我使用用户类的列表：

  private List<User> _UsersList;
        public List<User> users
        {
            get { return _UsersList; }
            set { _UsersList = value; }
        }

，然后投标工作！但如果我使用Users 类，绑定不起作用！

型号：

 public class User : ObservableObject
 {

        public int ID { get; set; }
        public string Name { get; set; }
        public int Age { get; set; }
        public bool IsPremiumUser { get; set; }
        public string selectedItem { get; set; }
        public string SelectedValue
        {
            get { return selectedItem; }
            set
            {
                selectedItem = value;
                //  suser.age = Convert.ToInt32(value);
                RaisePropertyChangedEvent("SelectedValue");
            }

        }
        public int[] myItem { get; set; }
        public int[] UserItems
        {
            get { return myItem; }
            set { myItem = value; }
        }
        private SelectedUser suser = new SelectedUser();
        public int selected { get; set; }
        public int Selected
        {
            get { return selected; }
            set
            {
                selected = value;
                suser.age = Convert.ToInt32(value);
                RaisePropertyChangedEvent("Selected");
            }

        }
    }
   public class Users : ObservableObject
    {
        private List<User> mylist = new List<User>();
        private List<User> list
        {
            get { return mylist; }
            set
            {
                mylist = value;

            }
        }
        public void Add(User user)
        {
            this.list.Add(user);
        }

        public User GetById(int id)
        {
            return this.list.First(u => u.ID == id);
        }

    }

视图模型：

 public class ViewModel : ObservableObject
 {

        public ViewModel()
        {
            users = new Users();
            for (int i = 0; i < 100000; ++i)
            {
                int[] numbers;
                numbers = new int[3] { 1, 2, 3 };
                var user = new User { ID = i, Name = "Name " + i.ToString(), Age = 20 + i, UserItems = numbers, SelectedValue = "0" };
                if (i == 2 || i == 4)
                {
                    user.IsPremiumUser = true;
                }
                users.Add(user);
            }

        }
        private Users _UsersList;
        public Users users
        {
            get { return _UsersList; }
            set { _UsersList = value; }
        }

        private int _currenuser;
        public int CurrentUser
        {
            get
            {
                return _currenuser;
            }
            set
            {
                _currenuser = value;

                RaisePropertyChangedEvent("CurrentUser");
            }
        }
    }

XAML：

<Window x:Class="WpfApplication1.MainWindow"
        xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
        xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
        xmlns:local="clr-namespace:WpfApplication1"
        xmlns:i="http://schemas.microsoft.com/expression/2010/interactivity"
        Icon="C:\Users\maninx2\Documents\Visual Studio 2013\Projects\SampleFormMaker1\WpfApplication1\abbott_point_of_care_HuT_icon.ico"
        Title="MainWindow" Height="700" Width="1249.129">
    <Window.Resources>
        <DataTemplate x:Key="NormalUserDataTemplate">
            <StackPanel>
                <TextBlock Text="{Binding Name}" />
                <TextBox Text="{Binding SelectedValue, UpdateSourceTrigger=PropertyChanged}" Width="300" />

            </StackPanel>
        </DataTemplate>
        <DataTemplate x:Key="PremiumUserDataTemplate">
            <StackPanel Background="LightBlue">
                <ComboBox  SelectedIndex="{Binding SelectedValue, UpdateSourceTrigger=PropertyChanged}" Text="{Binding Name}"  Width="300" ItemsSource="{Binding UserItems}"/>

            </StackPanel>
        </DataTemplate>
        <local:PremiumUserDataTemplateSelector x:Key="myPremiumUserDataTemplateSelector" />
    </Window.Resources>
    <TabControl Name="TabControl1">
        <TabControl.ItemContainerStyle>
            <Style TargetType="{x:Type TabItem}">
                <Setter Property="Visibility" Value="Collapsed"/>
            </Style>
        </TabControl.ItemContainerStyle>
        <TabItem Header="General">
            <ScrollViewer VerticalScrollBarVisibility="Auto">
                <StackPanel Height="800" Orientation="Horizontal" >
                    <ListView x:Name="myListView" ItemsSource="{Binding users,  Mode=TwoWay, UpdateSourceTrigger=PropertyChanged}" ItemTemplateSelector="{StaticResource myPremiumUserDataTemplateSelector}" SelectedIndex="{Binding CurrentUser, Mode=TwoWay, UpdateSourceTrigger=PropertyChanged}">
                    </ListView>
                    <ListView x:Name="myListView1" ItemsSource="{Binding users,  Mode=TwoWay, UpdateSourceTrigger=PropertyChanged}"   HorizontalAlignment="Stretch" >
                        <ListView.View>
                            <GridView>
                                <GridViewColumn Width="140" Header="Selected Values"
                 DisplayMemberBinding="{Binding SelectedValue}"  />

                            </GridView>
                        </ListView.View>
                    </ListView>
                    <Button Content="Next"
        HorizontalAlignment="Left"
        Margin="10,10,0,0"
        VerticalAlignment="Top"
        Width="75"
        Click="Button_Click"/>
                </StackPanel>

            </ScrollViewer>

        </TabItem>
        <TabItem Header="Second Tab">
            <StackPanel>
                <TextBlock Name="lbl1" Text="{Binding CurrentUser, UpdateSourceTrigger=PropertyChanged}"/>

            <Button Content="Previous"
        HorizontalAlignment="Left"
        Margin="10,10,0,0"
        VerticalAlignment="Top"
        Width="75"
        Click="Button_Click1"/>
            </StackPanel>
        </TabItem>

    </TabControl>

</Window>

Answer 1

您缺少从 ObservableCollection 继承用户。所以，WPF 引擎不知道如何从这个类中获取数据。

更新：

@user3033921：你从 ObservableObject 而非 ObservableCollection 继承了它。因此，问题是，如果您希望将此类从列表中识别出来，那么您必须让该类由 ICollection 对象继承，并且如果您希望该类是可观察的，它应该同时实现 ICollection 和 INotifyPropertyChange。因此，就@BradleyDotNet 而言，如果您没有任何特定理由来创建自己的类型，那么只需创建一个类型为 ObservableCollection 的用户对象。如果您有特定的用户类型需求，那么您可以从 ObserableCollection 派生它作为推荐的解决方案。但请记住，您不再希望在 Users 类中包含 List，因为您的类现在本身就是一个列表。因此，如果您有任何特定的实现，例如 GetByID，那么该类将如下所示：

public class Users :ObservableCollection<User>
{
    public User GetById(int id)
    {
        return this.First(u => u.ID == id);
    }

}