Question

我遇到了绑定数据到ComboBox的障碍。我正在开发Windows Phone 8.1中的应用程序，我想要做的就是在ComboBox中列出打印机。

这是我的XAML：

<ComboBox x:Name="cbxPrinters" 
          HorizontalAlignment="Left"
          Margin="153,150,0,0" 
          VerticalAlignment="Top" 
          Width="237">
    <ComboBox.ItemTemplate>
        <DataTemplate>
            <StackPanel Orientation="Vertical" Margin="2">
                <TextBlock Text="{Binding Name}"></TextBlock>
            </StackPanel>
        </DataTemplate>
    </ComboBox.ItemTemplate>
</ComboBox>

Public Class Printer

Public Id As Integer
Public Name As String

Public Function Populate(ByVal ResultString As String) As List(Of Printer)

    Dim _Results As List(Of String) = ResultString.Split(New String("|")).ToList

    Dim _Printers As New List(Of Printer)

    If _Results.Count >= 2 Then

        For i = 0 To _Results.Count - 1 Step 2
            Dim _Printer As New Printer

            With _Printer
                .Id = _Results(i)
                .Name = _Results(i + 1).Trim()
            End With

            _Printers.Add(_Printer)
        Next
    End If

    Return _Printers

End Function

End Class

这段代码将List(Of Printer)分配给ComboBox：

Protected Overrides Async Sub OnNavigatedTo(e As NavigationEventArgs)

    _Printer = New Printer

    _Printers = _Printer.Populate(Await GetPrinterList())

    If _Printers.Count > 0 Then
        cbxPrinters.ItemsSource = _Printers
    End If

End Sub

当我启动应用程序并进入此页面时，代码运行正常，但我还剩下54个空白选项可供选择。

Answer 1

在Zaggler的帮助下，在调查堆栈跟踪之后：

错误：BindingExpression路径错误：'COACH_HOUSE_SCAN_APP.Printer，COACH HOUSE SCAN APP，Version = 1.0.0.0，Culture = neutral，PublicKeyToken = null'找不到'Id'属性。

我稍微更改了这个类，以便Id和Name现在是Properties：

Public Property Id As Integer
Public Property Name As String

我按照Zaggler的建议设置了DisplayMemberPath和SelectedValuePath：

Protected Overrides Async Sub OnNavigatedTo(e As NavigationEventArgs)

    _Printer = New Printer

    _Printers = _Printer.Populate(Await GetPrinterList())

    If _Printers.Count > 0 Then
        cbxPrinters.ItemsSource = _Printers
        cbxPrinters.DisplayMemberPath = "Id"
        cbxPrinters.SelectedValuePath = "Name"
    End If

End Sub

我也删除了XAML的这一部分：

<ComboBox.ItemTemplate>
    <DataTemplate>
        <StackPanel Orientation="Vertical" Margin="2">
            <TextBlock Text="{Binding Name}"></TextBlock>
        </StackPanel>
    </DataTemplate>
</ComboBox.ItemTemplate>

让XMAL看起来像这样：

<ComboBox x:Name="cbxPrinters" 
      HorizontalAlignment="Left"
      Margin="153,150,0,0" 
      VerticalAlignment="Top" 
      Width="237">
</ComboBox>

这解决了我的问题，现在打印机现已列在ComboBox。

中

将数据绑定到ComboBox

1 个答案: