Question

我在这个论坛中搜索过，但我无法找到适合我特定情况的解决方案。

我正在尝试理解WPF和MVVM，并为此构建了一个简单的WPF。

我的数据模型是（我在这里实现了INotifyPropertyChanged，构造函数初始化了所有属性）：

namespace MyApp.ui.Models
{
    public class Server : INotifyPropertyChanged
    {
        private int id;
        public int ID
        {
            get { return id; }
            set { id = value; }
        }

        private string name;
        public string Name
        {
            get { return name; }
            set { name = value; OnPropertyChanged(Name); }
        }

        private string ipAddress;
        public string IPAddress
        {
            get { return ipAddress; }
            set { ipAddress = value; OnPropertyChanged(IPAddress); }
        }

        public Server(int ServerID, string ServerName, string ServerIpAddress)
        {
            ID = ServerID;
            Name = ServerName;
            IPAddress = ServerIpAddress;
        }

        public event PropertyChangedEventHandler PropertyChanged;

        private void OnPropertyChanged(string propertyName)
        {
            PropertyChangedEventHandler handler = PropertyChanged;
            if(handler != null)
            {
                handler(this, new PropertyChangedEventArgs( propertyName ) );
            }
        }
    }
}

我的ViewModel（由WPF Code Behind使用）：

namespace MyApp.ui.ViewModels
{
    public class ServersViewModel
    {
        private ObservableCollection<Server> server;
        public ObservableCollection<Server> Servers
        {
            get { return server; }
            set { server = value; }
        }

        public ServersViewModel()
        {
            Servers = new ObservableCollection<Server>
            {
                new Server(001, "Server001", @"192.168.254.3"),
                new Server(002, "Server002", @"100.92.0.200"),
                new Server(003, "Server003", @"64.32.0.3"),
                new Server(004, "Server004", @"172.10.0.4"),
                new Server(005, "Server005", @"165.23.0.233"),
                new Server(006, "Server006", @"81.22.22.6"),
                new Server(007, "Server007", @"10.10.0.7")
            };
        }

        public void ChangeServerNames()
        {
            //Before Change
            foreach (var item in Servers)
            {
                MessageBox.Show(item.Name);
            }

            int count = 1000;

            foreach (var item in Servers)
            {
                item.Name = "Server" + count.ToString();
                count += 1000;
            }

            //After Change
            foreach (var item in Servers)
            {
                MessageBox.Show(item.Name);
            }
        }
    }
}

我的WPF主视图（主菜单）使用以下XAML代码加载自定义用户控件（ExplorerView）（包含列表框，每个列表框项目包含1个复选框+图像+文本块）

<UserControl x:Class="MyApp.ui.Views.ExplorerView"
             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" 
             xmlns:local="clr-namespace:MyApp.ui.Views"
             mc:Ignorable="d" 
             d:DesignHeight="400" d:DesignWidth="200">
    <Grid>
        <ListBox ItemsSource="{Binding Servers}" Margin="2">
            <ListBox.ItemTemplate>
                <DataTemplate>
                    <CheckBox VerticalContentAlignment="Center" Margin="4">
                        <StackPanel Orientation="Horizontal">
                            <Image Source="/resources/server64.png" Height="30" Margin="4"></Image>
                            <TextBlock Text="{Binding Name}"
                                   VerticalAlignment="Center" Margin="4"></TextBlock>
                        </StackPanel>
                    </CheckBox>
                </DataTemplate>
            </ListBox.ItemTemplate>
        </ListBox>
    </Grid>
</UserControl>

最后，MainView Code Behind加载ServersViewModel，以便ExplorerView控件可以绑定数据。

namespace MyApp.ui
{
    /// <summary>
    /// Interaction logic for MainWindow.xaml
    /// </summary>
    public partial class MainWindow : Window
    {
        public ServersViewModel context { get; set; }

        public MainWindow()
        {
            InitializeComponent();

            context = new ServersViewModel();
            DataContext = context;
        }

        private void Button_Click(object sender, RoutedEventArgs e)
        {
            context.ChangeServerNames();
        }
    }
}

那就是说，我有两个问题：

1）正如您所看到的，在MainView中我实现了一个调用ServersViewModel.ChangeServerNames（）方法的Button click事件。问题是我的ExplorerView Control中的TextBlock没有显示更新的数据。

I ChangeServerNames（）我还使用MessageBox来显示更改前后的值，并且我看到值正在发生变化，不确定为什么ListBox / TextBlock没有更新...... !!! （我已经测试了许多其他可能的解决方案，但我不能让它工作......）

2）我读到MainView（和所有其他视图）中的CodeBehind应该只包含InitializeComponent（）;和“DataContext = context;”在最大... 如果是这样，那么应该放置按钮事件和其他按钮？

最后是MainWindow XAML的代码：

<Window
        xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
        xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
        xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
        xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
        xmlns:local="clr-namespace:MyApp.ui"
        xmlns:Views="clr-namespace:MyApp.ui.Views"
        x:Class="MyApp.ui.MainWindow"
        mc:Ignorable="d"
        Title="Server" MinHeight="720" MinWidth="1024"
        Height ="720" Width="1024">
    <Grid Margin="2">

        <Grid.ColumnDefinitions>
            <ColumnDefinition Width="200" />
            <ColumnDefinition Width="Auto"/>
            <ColumnDefinition />
        </Grid.ColumnDefinitions>

        <Grid.RowDefinitions>
            <RowDefinition Height="41*"/>
            <RowDefinition Height="608*"/>
            <RowDefinition Height="30"/>
        </Grid.RowDefinitions>

        <GridSplitter Grid.Column="1" Grid.Row="1"
              HorizontalAlignment="Center"
              VerticalAlignment="Stretch"
              Background="Gray" 
              ShowsPreview="True"
              Width="4" Margin="0,2,0,4"
              />

        <Views:MenuView Grid.ColumnSpan="3"/>
        <Views:FooterView Grid.Row="2" Grid.ColumnSpan="3" />
        <Views:ExplorerView Grid.Column="0" Grid.Row="1" />

        <!--Temp Tests-->
        <StackPanel Margin="12" Grid.Column="3" Grid.Row="1" Width="Auto" Height="Auto" Orientation="Horizontal" VerticalAlignment="Top" HorizontalAlignment="Left">
            <Button Margin="4" Width="120" Height="30" Content="Change Data Test..." Click="Button_Click" />
        </StackPanel>

    </Grid>
</Window>

感谢您的时间......

Answer 1

好的，我发现了问题......

而不是

set { name = value; OnPropertyChanged(Name); }
set { ipAddress = value; OnPropertyChanged(IPAddress); }

我在方法调用中缺少Quotesfor String参数正确的形式是

set { name = value; OnPropertyChanged("Name"); }
set { ipAddress = value; OnPropertyChanged("IPAddress"); }

很奇怪编译器没有抛出任何错误....方法 private void OnPropertyChanged（string propertyName）是＆＃34;要求＆＃34;将字符串作为输入参数。

AnyWay最好避免这些错误（我发现）是写这样的事件（调用者提供它自己的公共名称）：

private void OnPropertyChanged([CallerMemberName] String propertyName = "")
  {
    if (PropertyChanged != null)
    {
      PropertyChanged(this, new PropertyChangedEventArgs(propertyName));
    }
  }
}

现在我可以做到

set { name = value; OnPropertyChanged(); }
set { ipAddress = value; OnPropertyChanged(); }

谢谢。

WPF ListBox不更新

1 个答案: