为什么此WPF组合框未显示所选值？ [英] Why is this WPF ComboBox not showing the selected value?

问题描述

<CombobBox x:Name="cbo" 
           Style="{StaticResource ComboStyle1}"
           DisplayMemberPath="NAME"
           SelectedItem="{Binding Path=NAME}"
           SelectedIndex="1">
  <ComboBox.ItemTemplate>
    <DataTemplate>
      <Grid>
        <TextBlock Text="{Binding Path=NAME}"/>
      </Grid>
    </DataTemplate>
  </ComboBox.ItemTemplate>
</ComboBox>

在窗口中 OnLoaded 事件，我编写了代码来设置 ItemsSource ：

In the Window OnLoaded event, I wrote the code to set the ItemsSource:

cbo.ItemsSource = ser.GetCity().DefaultView;

在加载窗口时，我可以看到最初的第一个项目正在加载，但同时清除显示的项目。我处于这种情况下，我们将不胜感激。

While loading the window I can see that the initially the the first item is loading but at the same time it clears the displayed item. I am stuck in this scenario and any help is appreciated.

问候

Kishore

推荐答案

快速答案：从代码隐藏中设置 SelectedIndex = 1 。

QUICK ANSWER : Set SelectedIndex = 1 from code-behind.

首先执行XAML中的代码（ InitializeComponent（）方法），该方法将设置 SelectedIndex = 1 ，但 ItemsSource 尚未指定！因此 SelectedIndex 不会影响！ （记住，您不能在之前指定 ItemsSource InitializeComponent（））

It seems that the code in XAML executes first (the InitializeComponent() method), which sets SelectedIndex = 1, but ItemsSource is not specified yet! So SelectedIndex won't affect! (And remember, you cannot specify ItemsSource before InitializeComponent())

因此，您必须在设置 ItemsSource 之后手动设置 SelectedIndex = 1 。

So you have to manually set SelectedIndex = 1 after setting ItemsSource.

您应该这样做：

XAML

            <ComboBox x:Name="cbo"
                      Style="{StaticResource ComboStyle1}">
                <ComboBox.ItemTemplate>
                    <DataTemplate>
                        <Grid>
                            <TextBlock Text="{Binding Path=NAME}"/>
                        </Grid>
                    </DataTemplate>
                </ComboBox.ItemTemplate>
            </ComboBox>

代码

     cbo.ItemsSource = ser.GetCity().DefaultView;
     cbo.SelectedIndex = 1;

---

或者这个：

---

Or this:

XAML

            <ComboBox x:Name="cbo" Initialized="cbo_Initialized"
                      Style="{StaticResource ComboStyle1}">
                <ComboBox.ItemTemplate>
                    <DataTemplate>
                        <Grid>
                            <TextBlock Text="{Binding Path=NAME}"/>
                        </Grid>
                    </DataTemplate>
                </ComboBox.ItemTemplate>
            </ComboBox>

代码

    private void cbo_Initialized(object sender, EventArgs e)
    {
        cbo.SelectedIndex = 1;
    }

---

也请注意，我已删除 DisplayMemberPath = NAME ，因为您无法同时设置 DisplayMemberPath 和 ItemTemplate 同时。而且，使用 SelectedItem 或 SelectedIndex 而不是两者都使用。

---

Also note that i've removed DisplayMemberPath="NAME" because you cannot set both DisplayMemberPath and ItemTemplate at the same time. And also, use either SelectedItem or SelectedIndex, not both.

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