C# WPF DataBinding "Can' t 查找属性"

Question

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!

Answer 1

您的代码有两个问题:

1. 您需要将“列表”的路径告知 xaml(通过“ItemsSource”属性)。
2. 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>