我仍在努力了解 WPF 中的数据绑定(bind),因此在过去的 10 个小时里我在解决这个问题时遇到了一些问题:
我有一个名为 birdList 的对象,它包含一个 Bird 对象列表(bird1 和 bird2)。我已将对象中的所有属性公开。当我尝试将 Common_Name 属性数据绑定(bind)到 TextBlock 时,我什么也没得到。查看 Visual Studio 中的输出,我看到以下错误/警告:
System.Windows.Data Warning: 60 : BindingExpression (hash=47755470): Default mode resolved to OneWay
System.Windows.Data Warning: 78 : BindingExpression (hash=47755470): Activate with root item 'birdList'
System.Windows.Data Warning: 108 : BindingExpression (hash=47755470): At level 0 - for String.Bird found accessor <null>
System.Windows.Data Warning: 108 : BindingExpression (hash=47755470): At level 0 - for EnumerableCollectionView.Bird found accessor <null>
System.Windows.Data Warning: 108 : BindingExpression (hash=47755470): At level 0 - for Char.Bird found accessor <null>
System.Windows.Data Error: 40 : BindingExpression path error: 'Bird' property not found on 'object' ''String' (HashCode=-874795121)'.
System.Windows.Data Warning: 103 : BindingExpression (hash=47755470): Replace item at level 1 with {NullDataItem}
System.Windows.Data Warning: 88 : BindingExpression (hash=47755470): TransferValue - using fallback/default value ''
System.Windows.Data Warning: 89 : BindingExpression (hash=47755470): TransferValue - using final value ''
C#代码:
public Birds birdList { get; set; }
Bird bird1 { get; set; }
Bird bird2 { get; set; }
public MainWindow()
{
InitializeComponent();
birdList = new Birds();
bird1 = new Bird();
bird2 = new Bird();
bird1.Common_Name = "Mallard";
bird2.Common_Name = "Red-winged Blackbird";
birdList.Bird.Add(bird1);
birdList.Bird.Add(bird2);
birdList.Test = "Testing!";
this.DataContext = this;
this.Photos = (PhotoCollection)(Application.Current.FindResource("Photos") as ObjectDataProvider).Data;
this.Photos.Path = "E:\\Network Drive\\SarDonnie's Documents - Networked\\Birds\\Ducks, Geese, and Swans (Anatidae)\\Mallard\\Clear Lake Bay Park 1-18-16";
}
public class Birds
{
public string Test { get; set; }
public List<Bird> _Birds = new List<Bird>();
public List<Bird> Bird
{
get
{
return this._Birds;
}
}
}
public class Bird
{
public string Common_Name { get; set; }
}
XMAL:
<Grid Grid.Column="2">
<ContentControl Content="birdList">
<ContentControl.ContentTemplate>
<DataTemplate>
<StackPanel>
<TextBlock Height="50" Text="{Binding Bird.Common_Name,diag:PresentationTraceSources.TraceLevel=High}">
</TextBlock>
</StackPanel>
</DataTemplate>
</ContentControl.ContentTemplate>
</ContentControl>
</Grid>
我也试过这个来测试访问 birdList 对象中的 Test 属性:
<Grid Grid.Column="2">
<ContentControl Content="birdList">
<ContentControl.ContentTemplate>
<DataTemplate>
<StackPanel>
<TextBlock Height="50" Text="{Binding Test>
</TextBlock>
</StackPanel>
</DataTemplate>
</ContentControl.ContentTemplate>
</ContentControl>
</Grid>
我的问题是为什么我似乎找不到 birdList.Bird.Common_Name 属性或 birdList.Test 属性?
谢谢!
也请随时向我指出一些包含 WPF 信息的好网站。我讨厌用头敲这个键盘却一无所获!
最佳答案
您的代码有两个问题:
- 您需要将“列表”的路径告知 xaml(通过“ItemsSource”属性)。
- 使用接受集合的控件,例如 ListBox。
这是我的代码:
- MainWindow.xaml.cs
public partial class MainWindow : Window
{
public List<Bird> Birds { get; set; }
public MainWindow()
{
InitializeComponent();
Birds = new List<Bird>();
var bird1 = new Bird();
bird1.CommonName = "Mallard";
Birds.Add(bird1);
var bird2 = new Bird();
bird2.CommonName = "Red-winged Blackbird";
Birds.Add(bird2);
this.DataContext = this;
}
public class Bird
{
public string CommonName { get; set; }
}
}
- 主窗口.xaml
<Grid>
<ListBox ItemsSource="{Binding Birds}" DisplayMemberPath="CommonName" />
</Grid>
编辑
如果您需要在运行时从代码更新,请遵循 Jai 的建议。我只展示了问题的最小解决方案。
EDIT2
永远记得在绑定(bind)中使用properties,否则它不会起作用。
public class Birds
{
public string Test { get; set; }
//Binding source must be a property!!
public List<Bird> _Birds { get; set; } = new List<Bird>();
public List<Bird> Bird
{
get
{
return this._Birds;
}
}
}
<Grid>
<DataGrid ItemsSource="{Binding birdList._Birds}" />
</Grid>
关于C# WPF DataBinding "Can' t 查找属性",我们在Stack Overflow上找到一个类似的问题: https://stackoverflow.com/questions/37128242/