Find rows with CheckBox checked DataGridView - vb.net

Question

I put some code in to find what checkboxes have been checked in my DataGridView, but for some reason this isn't working.
I have looping through the rows in the DataGridView:
For Each row As DataGridViewRow In dgv_assets.Rows
Next
Then in here i have casted the first column as a DataGridViewCheckBoxCell:
For Each row As DataGridViewRow In dgv_assets.Rows
Dim chk As DataGridViewCheckBoxCell = DirectCast(row.Cells(0), DataGridViewCheckBoxCell)
Next
Then I am checking for all the checkboxes that have been checked:
For Each row As DataGridViewRow In dgv_assets.Rows
Dim chk As DataGridViewCheckBoxCell = DirectCast(row.Cells(0), DataGridViewCheckBoxCell)
If chk.Value = chk.TrueValue Then
MessageBox.Show("Checked")
End If
Next
For some reason even if the checkboxes are checked or unchecked they all hit the MessageBox.

Answer 1

Your code is almost correct, I guess the casting is the problem.
For Each row As DataGridViewRow In DataGridView1.Rows
Dim chk As DataGridViewCheckBoxCell = row.Cells(Column1.Name)
If chk.Value IsNot Nothing AndAlso chk.Value = True Then
MessageBox.Show("Checked: " + chk.RowIndex.ToString())
End If
Next
Column1 should be the column name of the DataGridViewCheckBoxCell that you are referring.

Answer 2

you can do in that simple way.
For i As Integer = 0 To dtg.RowCount - 1
If dtg.Item(0, i).Value = "True" Then
MsgBox("check")
End If
Next
I hope to be as helpful

Answer 3

Here is an example using a language extension method
Form level variable
Private Const CheckBoxColName As String = "Process"
Place the following in a code module, not a form or class
<System.Diagnostics.DebuggerStepThrough()> _
<Runtime.CompilerServices.Extension()> _
Public Function CheckBoxCount(ByVal GridView As DataGridView, ByVal ColumnIndex As Integer, ByVal Checked As Boolean) As Integer
Return (From Rows In GridView.Rows.Cast(Of DataGridViewRow)() Where CBool(Rows.Cells(ColumnIndex).Value) = Checked).Count
End Function
Use the extension method using the private variable above, CheckBoxColName which is the name of the column in the DataGridView as a DataGridViewCheckBoxColumn
If DataGridView1.CheckBoxCount(CheckBoxColName, True) > 0 Then
Dim Rows = DataGridView1.GetCheckedRows1(CheckBoxColName)
For Each Row In Rows
Console.WriteLine(Row.Cells.Item(1).Value)
Next
End If
If you want to use column index rather than column name the following will do so
<System.Diagnostics.DebuggerStepThrough()> _
<Runtime.CompilerServices.Extension()> _
Public Function CheckBoxCount(ByVal GridView As DataGridView, ByVal ColumnIndex As Integer, ByVal Checked As Boolean) As Integer
Return (From Rows In GridView.Rows.Cast(Of DataGridViewRow)() Where CBool(Rows.Cells(ColumnIndex).Value) = Checked).Count
End Function
Note both allow you to get check or un-checked.
The following gets the actual rows
<System.Diagnostics.DebuggerStepThrough()> _
<Runtime.CompilerServices.Extension()> _
Public Function GetCheckedRows1(ByVal GridView As DataGridView, ByVal ColumnName As String) As List(Of DataGridViewRow)
Dim Temp = (From Rows In GridView.Rows.Cast(Of DataGridViewRow)() Where Not Rows.IsNewRow).ToList
Return (From SubRows In Temp Where CBool(SubRows.Cells(ColumnName).Value) = True).ToList
End Function

Answer 4

you must first verify that TrueValue not null , since according to the documentation , the default is null. And then check if true.
Here Doc : TrueValue

Answer 5

Add CheckBox with Name CK1 And Add DataGridView with Name Dgrd and must the first cell be DataGridViewCheckBoxCell And Add the code:
Private Sub CK1_CheckedChanged(sender As Object, e As EventArgs) Handles CK1.CheckedChanged
If CK1.Checked = True Then
Try
Dim I As Integer
For I = 0 To Dgrd.Rows.Count - 1
Dim CHKRow As DataGridViewCheckBoxCell = Dgrd.Rows(I).Cells(0)
If CHKRow.Value = False Then
CHKRow.Value = True
End If
Next
Catch ex As Exception
End Try
Else
Try
Dim I As Integer
For I = 0 To Dgrd.Rows.Count - 1
Dim CHKRow As DataGridViewCheckBoxCell = Dgrd.Rows(I).Cells(0)
If CHKRow.Value = True Then
CHKRow.Value = False
End If
Next
Catch ex As Exception
End Try
End If
End Sub