VB.Net DataGridView

Question

I have DataGridView in my form in that two field are combo box.
When I start the application I get an message :
"he following exception occurred in the DataGridView: System.FormatException:
DataGridViewComboBoxCell value is not valid"

I have tried every thing and can not fix the problem.
Please help me.

Answer 1

If you have SQL-Server try out my code sample.

Answer 2

Hi,
I check your code and it works without problems. Try following demo.

Imports System.Collections.ObjectModel
Imports System.Data.SqlClient

Public Class Form29
  Private Sub Form1_Load(sender As Object, e As EventArgs) Handles MyBase.Load
    Me.Controls.Add(dgv)
    dgv.Columns.Add(New DataGridViewTextBoxColumn With {.HeaderText = "ID", .DataPropertyName = "ID"})
    con = New SqlConnection(My.Settings.cnSQL)
    LoadCBData()
    dgv.Columns.Add(HrsType)
    dgv.DataSource = GetData()
  End Sub

  Dim dgv As New DataGridView With {.Dock = DockStyle.Fill, .AutoGenerateColumns = False}
  Dim HrsType As New DataGridViewComboBoxColumn With {.DataPropertyName = "Type"}
  Dim con As SqlConnection

  Private Sub LoadCBData()
    Dim SQLHrsType As String = "SELECT CAST([hrsType] as CHAR(1)) as [hrsType] , CAST([hrsType] as CHAR(1)) + ' ' + [Description] as [HTDescription] FROM [dbo].[HrsType]"
    Dim SQLCmd As SqlCommand
    SQLCmd = New SqlCommand(SQLHrsType, con)
    con.Open()
    Dim HrsTypTbl As New DataTableHrsType
    HrsTypTbl.Columns.Add("hrsType", Type.GetType("System.String"))
    HrsTypTbl.Columns.Add("HTDescription", Type.GetType("System.String"))
    Dim HrTyDA As SqlDataAdapter = New SqlDataAdapter(SQLHrsType, con)
    HrTyDA.Fill(HrsTypTbl)
    HrsType.DataSource = HrsTypTbl
    HrsType.ValueMember = "hrsType"
    HrsType.DisplayMember = "HTDescription"
    con.Close()
  End Sub

  Private Function GetData() As ObservableCollection(Of Data)
    Dim types() As String = {"A", "B", "C"}
    Dim rnd As New Random
    Dim l As New ObservableCollection(Of Data)
    For i = 1 To 10
      l.Add(New Data With {.ID = i, .Type = types(rnd.Next(0, types.Count))})
    Next
    Return l
  End Function

  Public Class Data
    Public Property ID As Integer
    Public Property Type As String
  End Class

  Public Class DataTableHrsType
    Inherits DataTable
  End Class

End Class

You get error "... DataError event" if your data in database are incorrect. Check your data. If you don't have a record in HrsType corresponding to DataPropertyName-field in DataSource of DataGridView you get this error.

Data in Datasource of DataGridView:

ID: 1, Type:B
ID: 2, Type:C
ID: 3, Type:C
ID: 4, Type:A
ID: 5, Type:C
ID: 6, Type:C
ID: 7, Type:A
ID: 8, Type:B
ID: 9, Type:A
ID: 10, Type:A

Data in DataTable HrsType:

hrsType: A, HTDescription: A Type A
hrsType: B, HTDescription: B Type B