Execute or Initilize a Class??

Question

Hallo

I have a Bindinglist of Objects bound to a datagridview. I populate this list with a Sub. Problem is these list of objects are not initialized unless i click or activate the datagridview. Is there a way to initilize these objects so they do their work without activating them first?.

Thanks

Answer 1

Hi, here is my sample code . also you can see the problem in the attached Gif,

basically i pass my properties to another class and do some calculations there and get the total in "Sample" class. If the DGV is active then it returns the total. How can i fix it?

Imports System.ComponentModel  
Imports System.Reflection  
Imports System.Linq.Expressions  
  
Public Class Form1  
  
    Public SampleList As New Samples  
    Public WithEvents BS_SampleList As New BindingSource  
  
    Public CalList As New BindingList(Of Calculation)  
    Public BS_SampleCalculation As New BindingSource  
  
    Private Sub Form1_Load(sender As Object, e As EventArgs) Handles MyBase.Load  
  
        BS_SampleList.DataSource = SampleList  
        DataGridView1.DataSource = BS_SampleList  
  
        BS_SampleCalculation.DataSource = CalList  
        DataGridView2.DataSource = BS_SampleCalculation  
  
    End Sub  
  
    Private Class PropertyList  
        Inherits List(Of Calculation)  
        Public Sub New(obj As Object)  
            For Each prop In obj.GetType().GetProperties(BindingFlags.Public Or BindingFlags.Instance)  
                Me.Add(New Calculation(obj, prop))  
                Debug.Print(obj.ToString & prop.Name)  
            Next  
        End Sub  
    End Class  
  
  
    Public Class Calculation  
        Public Sub New(obj As Object, prop As PropertyInfo)  
            Me.obj = obj  
            Me.prop = prop  
        End Sub  
  
        Private obj As Object  
        Private prop As PropertyInfo  
        Public ReadOnly Property ID As String  
            Get  
                Return Me.prop.Name  
            End Get  
        End Property  
        Public ReadOnly Property Description As String  
            Get  
                For Each att As CustomAttributeData In Me.prop.CustomAttributes  
                    Dim args = att.ConstructorArguments  
                    If args.Count > 0 Then Return args(0).ToString.Substring(1, args(0).ToString.Length - 2)  
                Next  
                Return String.Empty  
            End Get  
        End Property  
        Public Property Quantity As Object  
            Get  
                Return Me.prop.GetValue(Me.obj)  
            End Get  
            Set(value As Object)  
                Me.prop.SetValue(Me.obj, CInt(value))  
            End Set  
        End Property  
        Public ReadOnly Property Cost As Integer?  
            Get  
                If ID = "TT" Then  
                    Dim Tot As Integer? = Form1.getTot()  
                    prop.SetValue(Me.obj, Tot)  
                    Return Form1.getTot()  
                Else  
                    If CInt(Me.prop.GetValue(Me.obj)) > 0 Then  
                        Return CInt(Me.prop.GetValue(Me.obj)) * 100  
                    Else  
                        Return 1000  
                    End If  
                End If  
            End Get  
        End Property  
  
    End Class  
  
    Public Function getTot() As Integer?  
        Return Aggregate e In CalList Where e.ID Like "I*" Into Sum(e.Cost)  
    End Function  
  
  
    Public Class Sample  
  
        <Description("Item 1")> <Browsable(False)> Public Property I1 As Integer?  
        <Description("Item 2")> <Browsable(False)> Public Property I2 As Integer?  
        <Description("Item 3")> <Browsable(False)> Public Property I3 As Integer?  
        <Description("Total")> <Browsable(False)> Public Property TT As Integer?  
        Public Property ID As String  
        Public Property Name As String  
        Public ReadOnly Property CTotal As Integer?  
            Get  
                Return TT  
            End Get  
        End Property  
  
    End Class  
  
    Public Class Samples  
        Inherits BindingList(Of Sample)  
    End Class  
  
  
    Private Sub Btn_AddSample_Click(sender As Object, e As EventArgs) Handles Btn_AddSample.Click  
  
        SampleList.Add(New Sample With {.ID = 1, .Name = "Sample1"})  
  
    End Sub  
  
    Private Sub BS_SampleList_CurrentChanged(sender As Object, e As EventArgs) Handles BS_SampleList.CurrentChanged  
  
        Dim CurrentS = CType(BS_SampleList.Current, Sample)  
  
        If Not CurrentS Is Nothing Then  
            CalList.Clear()  
            Dim selected_properties = CurrentS.GetType().GetProperties().Where(Function(p) p.GetCustomAttributes().Any(Function(a) TypeOf a Is DescriptionAttribute))  
            For Each prop In selected_properties  
                CalList.Add(New Calculation(CurrentS, prop))  
            Next  
  
        End If  
  
    End Sub  
  
    Private Sub Button3_Click(sender As Object, e As EventArgs) Handles Button3.Click  
        DataGridView2.Refresh()  
        DataGridView1.Refresh()  
    End Sub  
End Class  
  

Answer 2

Hi @Hobbyist_programmer ,
You can consider using the following remedies:
When you click cell in DataGridView1, TabControl will switch to the TabPage where DataGridView2 is located, and then return to the original TabPage.

    Private pageName As String  
    Private pageIsChanged = False  
    Private Sub DataGridView1_CellClick(sender As Object, e As DataGridViewCellEventArgs) Handles DataGridView1.CellClick  
  
        If DataGridView1.Columns(DataGridView1.CurrentCell.ColumnIndex).Name = "CTotal" Then  
  
            If Not TabControl1.SelectedTab.Name.Equals("TabPage2") Then  
                pageName = TabControl1.SelectedTab.Name  
                TabControl1.SelectedTab = TabControl1.TabPages("TabPage2")  
                pageIsChanged = True  
            End If  
        End If  
    End Sub  
    Private Sub DataGridView1_CellMouseLeave(sender As Object, e As DataGridViewCellEventArgs) Handles DataGridView1.CellMouseLeave  
        If pageIsChanged Then  
            TabControl1.SelectedTab = TabControl1.TabPages(pageName)  
            pageIsChanged = False  
        End If  
    End Sub  

Result of my test :

Hope it could be helpful.

Best Regards,
Xingyu Zhao
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