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Adding Text and Value to ComboBox in WPF Application

Following code is okey in vb.net and Windows Form Application.

Public Class Form1
Private Sub Form1_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load
Dim comboSource As New Dictionary(Of String, String)()
comboSource.Add("1", "Sunday")
comboSource.Add("2", "Monday")
comboSource.Add("3", "Tuesday")
comboSource.Add("4", "Wednesday")
comboSource.Add("5", "Thursday")
comboSource.Add("6", "Friday")
comboSource.Add("7", "Saturday")
ComboBox1.DataSource = New BindingSource(comboSource, Nothing)
ComboBox1.DisplayMember = "Value"
ComboBox1.ValueMember = "Key"
End Sub
Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click
Dim key As String = DirectCast(ComboBox1.SelectedItem, KeyValuePair(Of String, String)).Key
Dim value As String = DirectCast(ComboBox1.SelectedItem, KeyValuePair(Of String, String)).Value
MessageBox.Show(key & " " & value)
End Sub
End Class


I want to convert above codes to WPF Application.

xaml

<Window x:Class="MainWindow"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
Title="MainWindow" Height="350" Width="525">
<Grid>
<ComboBox x:Name="ComboBox1" Height="20" Width="150"/>
<Button x:Name="Button1" Height="20" Width="80" VerticalAlignment="Top" Content="Click Me"/>
</Grid>
</Window>


vb.net

Class MainWindow
Private Sub MainWindow_Loaded(sender As Object, e As RoutedEventArgs) Handles Me.Loaded
Dim comboSource As New Dictionary(Of String, String)()
comboSource.Add("1", "Sunday")
comboSource.Add("2", "Monday")
comboSource.Add("3", "Tuesday")
comboSource.Add("4", "Wednesday")
comboSource.Add("5", "Thursday")
comboSource.Add("6", "Friday")
comboSource.Add("7", "Saturday")
ComboBox1.DataSource = New BindingSource(comboSource, Nothing)
ComboBox1.DisplayMember = "Value"
ComboBox1.ValueMember = "Key"
End Sub
Private Sub Button1_Click(sender As Object, e As RoutedEventArgs) Handles Button1.Click
Dim key As String = DirectCast(ComboBox1.SelectedItem, KeyValuePair(Of String, String)).Key
Dim value As String = DirectCast(ComboBox1.SelectedItem, KeyValuePair(Of String, String)).Value
MessageBox.Show(key & " " & value)
End Sub
End Class


Linked picture shows the errors: https://prnt.sc/kcig7j

So, how can I solve that errors?

1 Answer
1

The WPF equivalents for the WinForms properties are as follows:

DataSource -> ItemsSource
DisplayMember -> DisplayMemberPath
ValueMember -> SelectedValuePath


Also, bear in mind that you can set properties in either code-behind or in XAML, so your ComboBox definition could look like this:

ComboBox

<ComboBox x:Name="ComboBox1" Height="20" Width="150" DisplayMemberPath="Value" SelectedValuePath="Key" />


I personally would find it easier to set the ItemsSource property in code-behind:

ItemsSource

Dim comboSource As New Dictionary(Of String, String)()
comboSource.Add("1", "Sunday")
comboSource.Add("2", "Monday")
comboSource.Add("3", "Tuesday")
comboSource.Add("4", "Wednesday")
comboSource.Add("5", "Thursday")
comboSource.Add("6", "Friday")
comboSource.Add("7", "Saturday")
ComboBox1.ItemsSource = comboSource


W.R.T. your event handler, you have a double cast to KeyValuePair(Of String, String); you should probably cast only once and store the casted value in a variable. But in this particular case, you don't have to even cast the SelectedItem. Instead, you can cast the sender to a ComboBox and read the Text and Value properties:

KeyValuePair(Of String, String)

SelectedItem

sender

ComboBox

Text

Value

Dim cmb As ComboBox = sender
MessageBox.Show($"Key: {cmb.SelectedValue}, Value: {cmb.Text}')


Also note that you can just as easily use an Integer for your dictionary key as a String:

Integer

String

Dim days = {"Sunday", "Monday", "Tuesday", "Wednesday", "Thursday", "Friday", "Saturday"}
Dim comboSource = days
.Select(Function(x, index) (x, index+1))
.ToDictionary(Function(x) x.Item2, Function(x) x.Item1)


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