MVVM WPF数据绑定问题
本文关键字:问题 数据绑定 WPF MVVM | 更新日期: 2023-09-27 18:13:53
我是MVVM和WPF的新手,我有下面的模型,我想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,我从我的代码失踪?!
如果使用Class of Users,则使用来自Class User的List:
private List<User> _UsersList;
public List<User> users
{
get { return _UsersList; }
set { _UsersList = value; }
}
,那么投标工作!,但如果我使用Users
类,绑定不起作用!
模型:
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);
}
}
ViewModel:
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>
您没有从ObservableCollection继承Users。因此,WPF引擎不知道如何从这个类中获取数据。
更新:@user3033921:你从ObservableObject而不是ObservableCollection继承了它。问题是,如果你想要这个类被识别为一个列表那么你需要让那个类被一个ICollection对象继承如果你想要那个类是可观察的它应该同时实现ICollection和INotifyPropertyChange。所以,按照@BradleyDotNet的观点,如果你没有任何特殊的理由来创建你自己的类型,那么就创建一个类型为ObservableCollection的用户对象。如果你有一个特定的需要有一个类型Users,那么你可以从ObserableCollection作为推荐的解决方案派生它。但请记住,您不想在Users类中再拥有List,因为您的类现在本身就是一个列表。所以,如果你有任何特定的实现,比如GetByID,那么这个类应该是这样的:
public class Users :ObservableCollection<User>
{
public User GetById(int id)
{
return this.First(u => u.ID == id);
}
}