选项卡控件中的MVVM列表框未更新
本文关键字:列表 更新 MVVM 控件 选项 | 更新日期: 2023-09-27 18:28:57
我正在处理更新问题。我有选项卡控件,列表框绑定到可观察集合
ListBox HorizontalAlignment="Center" Height="450" VerticalAlignment="Top" Width="250"
x:Name="LbxMenu" Background="{x:Null}" BorderBrush="{x:Null}"
ItemsSource="{Binding TestListsNames}" FontFamily="Segoe UI Semilight" FontSize="18"/>
视图模型:
private ObservableCollection<string> _testListsName;
public ObservableCollection<string> TestListsNames
{
get { return _testListsName; }
set{ _testListsName = value; }
}
在将实体插入数据库后,有一个事件调用我的ViewModel中的TestListInitialize方法,该方法应该刷新集合,它的工作方式正如我在调试器中看到的那样。但列表框并没有刷新,我必须重新启动应用程序才能看到更改。当它在单独的窗口中时效果很好,但当我将ui更改为选项卡控件时,它就不起作用了。
更新功能:
private void TestListNamesInitialize()
{
TestListsNames = db.GetTestListNamesFromDatabase();
if (TestListsNames.Count != 0) CanLoad = true;
}
初始窗口:
<Controls:MetroWindow
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
x:Class="Test.View.InitialWindow"
xmlns:Controls="clr-namespace:MahApps.Metro.Controls;assembly=MahApps.Metro"
xmlns:tabdata="clr-namespace:Test.View.TabItems"
Title="Testownik" Height="600" Width="900" ShowTitleBar="True" ResizeMode="NoResize" Icon="../GraphicResources/Icon.ico">
<Controls:MetroWindow.RightWindowCommands>
<Controls:WindowCommands>
<Button Content="settings" />
<Button>
<StackPanel Orientation="Horizontal">
<TextBlock Margin="4 0 0 0"
VerticalAlignment="Center"
Text="about" />
</StackPanel>
</Button>
</Controls:WindowCommands>
</Controls:MetroWindow.RightWindowCommands>
<Controls:MetroAnimatedTabControl x:Name ="MainTabControl">
<TabItem Header="Learn" Width="280">
<tabdata:LearnTabItem/>
</TabItem>
<TabItem Header="Database" Width="280">
<tabdata:DatabaseTabItem/>
</TabItem>
<TabItem Header="Statistics" Width="299">
<tabdata:StatisticsTabItem/>
</TabItem>
</Controls:MetroAnimatedTabControl>
代码背后:
public partial class InitialWindow : MetroWindow
{
InitialWindowViewModel viewModel=new InitialWindowViewModel();
public InitialWindow()
{
InitializeComponent();
DataContext = viewModel;
}
}
}
数据库选项卡项:
<UserControl x:Class="Test.View.TabItems.DatabaseTabItem"
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:Controls="clr-namespace:MahApps.Metro.Controls;assembly=MahApps.Metro"
xmlns:tabData="clr-namespace:Test.View.TabItems"
Height="500" Width="900" Background="White" BorderBrush="Transparent">
<UserControl.Resources>
</UserControl.Resources>
<Grid>
<Controls:MetroAnimatedTabControl x:Name ="DatabaseTabControl" Grid.Column="0" TabStripPlacement="Left" >
<TabItem Header="Choose" Width="250" >
<tabData:ChooseFromDbTabItem/>
</TabItem>
<TabItem Header="Add" Width="250">
<tabData:AddToDbTabItem/>
</TabItem>
<TabItem Header="Remove" Width="250">
<tabData:DeleteFromDbTabItem/>
</TabItem>
</Controls:MetroAnimatedTabControl>
</Grid>
代码背后:
DatabaseViewModel vm = new DatabaseViewModel();
public DatabaseTabItem()
{
InitializeComponent();
DataContext = vm;
}
}
从数据库选项卡项中选择:
<UserControl x:Class="Test.View.TabItems.ChooseFromDbTabItem"
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:Test.View.TabItems"
xmlns:Controls="clr-namespace:MahApps.Metro.Controls;assembly=MahApps.Metro"
mc:Ignorable="d"
d:DesignHeight="500" d:DesignWidth="650" Background="White" BorderBrush="Transparent">
<Grid>
<ListBox HorizontalAlignment="Center" Height="450" VerticalAlignment="Top" Width="250"
x:Name="LbxMenu" Background="{x:Null}" BorderBrush="{x:Null}"
ItemsSource="{Binding TestListsNames}" FontFamily="Segoe UI Semilight" FontSize="18"/>
</Grid>
代码背后:
public partial class ChooseFromDbTabItem : UserControl
{
public ChooseFromDbTabItem()
{
InitializeComponent();
}
}
您必须引发PropertyChanged
事件,因为您更改了整个集合,而不是单个项目(如果您更改了通过Observable更新的单个项目)。
private ObservableCollection<string> _testListsName;
public ObservableCollection<string> TestListsNames
{
get { return _testListsName; }
set
{
if (_testListsName != value)
{
_testListsName = value;
NotifyPropertyChanged("TestListsNames");
}
}
}
public event PropertyChangedEventHandler PropertyChanged;
private void NotifyPropertyChanged(string property)
{
if (PropertyChanged != null)
PropertyChanged(this, new PropertyChangedEventArgs(property));
}
使用属性setter替换列表时,不会引发PropertyChanged事件。一般来说,尽量使集合属性只读,以降低此类错误的风险。相反,清除列表并重新填充它。这将确保视图收到任何更改的通知。
public class ViewModel
{
private readonly ObservableCollection<string> _testListsName;
public ObservableCollection<string> TestListsNames
{
get { return _testListsName; }
}
private void TestListNamesInitialize()
{
_testListsName.Clear();
foreach(string name in db.GetTestListNamesFromDatabase())
{
_testListsName.Add(name);
}
if (_testListsNames.Count != 0) CanLoad = true;
}
}
但是,请注意,这将使用.Add()调用在每个项上引发已更改的事件。请参阅此处:我可以以某种方式暂时禁用WPF数据绑定更改吗?
编辑:从您更新的代码。还可以看出,您没有在ChooseFromDbTabItem上设置DataContext。您需要将DataContext属性绑定到公开集合的视图模型:
<TabItem Header="Choose" Width="250" >
<tabData:ChooseFromDbTabItem DataContext="{Binding}" />
</TabItem>