[英]ListBox doesn't refresh?
我在使用列表框的Visual Studio(wpf)上遇到了問題。 如果我想從數據庫插入或刪除一些數據,那么它們正在工作,但如果我點擊menuitem一次,列表框將會刷新。 我認為這是由於加載方法,但為什么不刷新數據呢?
這是我的XAML代碼:
<UserControl x:Class="WpfApplication1.AutorenBearbeiten"
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:WpfApplication1"
mc:Ignorable="d"
d:DesignHeight="400" d:DesignWidth="300" Loaded="UserControl_Loaded">
<Grid>
<Grid.RowDefinitions>
<RowDefinition Height="Auto" />
<RowDefinition Height="*" />
</Grid.RowDefinitions>
<Grid.ColumnDefinitions>
<ColumnDefinition Width="28*" />
<ColumnDefinition Width="36*" />
</Grid.ColumnDefinitions>
<TextBlock Text="Medien" Grid.ColumnSpan="2"
FontSize="16" />
<ListBox x:Name="box" Grid.Row="1">
<ListBox.ItemTemplate>
<DataTemplate>
<TextBlock Text="{Binding Path=at_nachname}" />
</DataTemplate>
</ListBox.ItemTemplate>
</ListBox>
<StackPanel DataContext="{Binding ElementName=box,Path=SelectedItem}" Grid.Column="1" Grid.Row="1" >
<TextBlock Text="Autoren_id" />
<TextBox Text="{Binding Path=at_id}" MaxLength="5"/>
<TextBlock Text="Vorname" />
<TextBox Text="{Binding Path=at_vorname}" MaxLength="30"/>
<TextBlock Text="Nachname" />
<TextBox Text="{Binding Path=at_nachname}" MaxLength="30"/>
<TextBlock Text="Geburtsdatum" />
<TextBox MaxLength="30" Text="{Binding Path=at_gebDatum, StringFormat=dd.MM.yyyy}" />
<Button Name="speichern" Height="23" Margin="4" Click="speichern_Click">Änderungen speichern</Button>
<Button Name="loeschen" Height="23" Margin="4" Click="loeschen_Click">Löschen</Button>
<StackPanel DataContext="{Binding ElementName=box}" Grid.Column="1" Grid.Row="1" >
<TextBlock Text="Autoren_id" />
<TextBox x:Name="id" MaxLength="5"/>
<TextBlock Text="Vorname" />
<TextBox x:Name="vorname" MaxLength="30"/>
<TextBlock Text="Nachname" />
<TextBox x:Name="nachname" MaxLength="30"/>
<TextBlock Text="Geburtsdatum" />
<TextBox x:Name="datum" MaxLength="30"/>
<Button x:Name="neubutton" Height="23" Margin="4" Click="neu_Click">Neu</Button>
<TextBlock Name="submitfehler" FontWeight="Bold" Foreground="Red" />
</StackPanel>
</StackPanel>
</Grid>
</UserControl>
這是xaml.cs文件:
using System;
using System.Collections.Generic;
using System.Data.Entity;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Windows;
using System.Windows.Controls;
using System.Windows.Data;
using System.Windows.Documents;
using System.Windows.Input;
using System.Windows.Media;
using System.Windows.Media.Imaging;
using System.Windows.Navigation;
using System.Windows.Shapes;
namespace WpfApplication1
{
/// <summary>
/// Interaction logic for AutorenBearbeiten.xaml
/// </summary>
public partial class AutorenBearbeiten : UserControl
{
libraryEntities6 db = new libraryEntities6();
public AutorenBearbeiten()
{
InitializeComponent();
}
private void UserControl_Loaded(object sender, RoutedEventArgs e)
{
var erg = db.a_autor;
erg.Load();
box.ItemsSource = erg.Local.OrderBy(m => m.at_id);
box.ItemsSource =
(from m in db.a_autor
orderby m.at_id
select m).ToList();
}
private void speichern_Click(object sender, RoutedEventArgs e)
{
try
{
db.SaveChanges();
}
catch(Exception e1)
{
submitfehler.Text = e1.Message;
}
}
private void loeschen_Click(object sender, RoutedEventArgs e)
{
a_autor am = (a_autor)box.SelectedItem;
if (am != null)
{
db.a_autor.Remove(am);
db.SaveChanges();
box.Items.Refresh();
}
}
private void neu_Click(object sender, RoutedEventArgs e)
{
a_autor autor = new a_autor();
autor.at_id = id.Text;
autor.at_vorname = vorname.Text;
autor.at_nachname = nachname.Text;
autor.at_gebDatum = Convert.ToDateTime(datum.Text);
//s1.s_k_klasse = liklassen.SelectedValue.ToString() setzt die Klasse via foreign key
//db.schuelers.AddObject(s1);
db.a_autor.Add(autor);
box.Items.Refresh();
/*
((klassen))liklassen.SelectedItem).schuelers.Add(s1); //setzt die klasse durch zuweisen zum nav.Property
lischueler.Items.Refresh(); //nötig weil das navigational seit ER 5 nicht observable ist
*/
}
}
}
窗口中的圖片如下:
您應該使用MVVM模式而不是代碼隱藏並使用屬性更改。 谷歌的第一個結果:
https://www.codeproject.com/Articles/819294/WPF-MVVM-step-by-step-Basics-to-Advance-Level
我希望它對你有所幫助。
胡安
您可以創建ObservableCollection
而不是綁定到List
。 ObservableCollection實現了INotifyPropertyChanged
因此它可以在容器中發生更改時發送通知。
另外,我建議你試試
public void RefreshListBox()
{
box.ItemsSource =
(from m in db.a_autor
orderby m.at_id
select m).ToList();
}
並在db.SaveChanges()
之后調用它
ListBox和數據庫之間沒有神奇的連接,因此當您調用DbContext的Add或Remove方法時,ListBox不會受到影響。
你應該做的是將ListBox的ItemsSource屬性設置為ObservableCollection<a_autor>
,然后調用此方法的Add / Remove方法,同時調用DbContext的Add / Remove方法:
System.Collections.ObjectModel.ObservableCollection<a_autor> _sourceCollection;
private void UserControl_Loaded(object sender, RoutedEventArgs e)
{
var erg = db.a_autor;
erg.Load();
_sourceCollection = new System.Collections.ObjectModel.ObservableCollection<a_autor>((from m in db.a_autor
orderby m.at_id
select m).ToList());
box.ItemsSource = _sourceCollection;
}
private void loeschen_Click(object sender, RoutedEventArgs e)
{
a_autor am = (a_autor)box.SelectedItem;
if (am != null)
{
_sourceCollection.Remove(am);
db.a_autor.Remove(am);
db.SaveChanges();
box.Items.Refresh();
}
}
private void neu_Click(object sender, RoutedEventArgs e)
{
a_autor autor = new a_autor();
autor.at_id = id.Text;
autor.at_vorname = vorname.Text;
autor.at_nachname = nachname.Text;
autor.at_gebDatum = Convert.ToDateTime(datum.Text);
_sourceCollection.Add(autor);
db.a_autor.Add(autor);
box.Items.Refresh();
}
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