Error on double click on datagrid in WPF VB.NET

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I wrote a simple wpf datagrid. So when I double click on a cell, the program crashes. I should add that I checked this post: https://stackoverflow.com/questions/19334326/wpf-datagrid-edititem-is-not-allowed-for-this-view-exception[^] But there was not an answer for my question. The answer there is for datagrid which is in windows form.

What I have tried:

This is my XAML code:

XML

<Window x:Class="MainWindow"
        xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
        xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
        xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
        xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
        xmlns:local="clr-namespace:WpfApp4"
        mc:Ignorable="d"
        Title="MainWindow" Height="350" Width="525">
    <Grid Margin="10">
        <DataGrid x:Name="myDGList" 
                  AutoGenerateColumns="False"
                  HorizontalContentAlignment="Stretch"
                  VerticalContentAlignment="Stretch"
                  FontFamily="Tahoma"
                  FontSize="12"
                  IsReadOnly="False"
                  GridLinesVisibility="All"
                  CanUserAddRows="True"
                  CanUserDeleteRows="True">

            <DataGrid.Columns>
                <DataGridTextColumn Header="Number" IsReadOnly="False" Width="100" Binding="{Binding employeeID}"/>
                <DataGridTextColumn Header="Name" IsReadOnly="False" Width="100" Binding="{Binding employeeName}"/>
                <DataGridTextColumn Header="Address" IsReadOnly="False" Width="*" Binding="{Binding employeeAddress}"/>
                <DataGridTextColumn Header="City" IsReadOnly="False" Width="*" Binding="{Binding employeeCity}"/>
                <DataGridTextColumn Header="State" IsReadOnly="False" Width="*" Binding="{Binding employeeState}"/>
            </DataGrid.Columns>
        </DataGrid>

This is the MainWindow code:

XML

Class MainWindow
    Sub New()
        InitializeComponent()
        Dim JohnSmith As Employee = New Employee
        JohnSmith.employeeID = "001"
        JohnSmith.employeeName = "John smith"
        JohnSmith.employeeAddress = "122 made up Lane"
        JohnSmith.employeeCity = "cameden"
        JohnSmith.employeeState = "New Jersy"
        myDGList.Items.Add(JohnSmith)
    End Sub
    Partial Class Employee
        Public Property employeeID As String
        Public Property employeeName As String
        Public Property employeeAddress As String
        Public Property employeeCity As String
        Public Property employeeState As String
    End Class
End Class

So after I double click on a cell, program crashes and bellow page opens in visual studio:

https://i.stack.imgur.com/jVYCn.png[^]:
System.InvalidOperationException:
'EditItem' is not allowed for this view

Posted 20-Jun-23 7:52am

Sh.H.

Updated 24-Jun-23 21:49pm

v5

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Comments

Richard Deeming 20-Jun-23 14:23pm

Don't post screenshots of your error messages. That error dialog has a "copy details" link which will copy the full exception details to the clipboard in text.

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Richard Deeming · Answer 1 · 2023-06-20T21:57:00

I was able to reproduce the problem. As far as I can see, it's due to the fact that you're adding items directly to the DataGrid's Items collection.

If I change your code to add the employee to a List(Of Employee) instead, and assign that list to the DataGrid's ItemSource property, then the code works as expected. You will be able to edit the existing row, and add new rows.

VB.NET

Sub New()
    InitializeComponent()
    
    Dim JohnSmith As Employee = New Employee
    JohnSmith.employeeID = "001"
    JohnSmith.employeeName = "John smith"
    JohnSmith.employeeAddress = "122 made up Lane"
    JohnSmith.employeeCity = "cameden"
    JohnSmith.employeeState = "New Jersy"
    
    Dim employeeList As New System.Collections.Generic.List(Of Employee)
    employeeList.Add(JohnSmith)
    
    myDGList.ItemsSource = employeeList
End Sub

cmarcotte · Answer 2 · 2023-06-20T16:07:00

Solution 1

According to this page :
Specify the Edit Mode for DataGridView Control - Windows Forms .NET Framework | Microsoft Learn[^]

You must have

Quote:
The ReadOnly properties of the cell, row, column, and control are all set to false.

Posted 20-Jun-23 16:07pm

cmarcotte

Comments

Richard Deeming 21-Jun-23 3:43am

Based on the XAML code in the question, all of the columns already have IsReadOnly="False", as does the grid.

Sh.H. 22-Jun-23 9:15am

Yes. All are already False.