我正试图通过cellvaluechanged事件为我的datagridviewcomboboxcell设置selectedindex，即当我更改数据网格行中的某个值时，该列应该会自动更改。这是代码
Private Sub DataGridView1_CellValueChanged(sender As Object, e As System.Windows.Forms.DataGridViewCellEventArgs) Handles DataGridView1.CellValueChanged
Try
If Me.DataGridView1.Rows(e.RowIndex).Cells(2).Value.ToString <> Nothing Then
Me.DataGridView1("unit_code", e.RowIndex).Value = "1"
MsgBox(Me.DataGridView1.Rows(e.RowIndex).Cells(6).Value)
End If
Else
Exit Sub
End If
End If
Catch ex As Exception
MessageBox.Show(ex.Message, "Message", MessageBoxButtons.OK, MessageBoxIcon.Error)
End Try
我的datagridview已绑定到数据集。搜索了许多站点并进行了所有研究，得到了上述需要将valuemember设置为.value部分的解决方案。即使在这样做之后，它也会产生system.formatexception:datagridviewcomboboxcell value is not valid。
请帮帮我。
[编辑]
表格结构unit_code descp
0 nbsp nbsp nbsp nbsp nbsp -
1 nbsp nbsp nbsp nbsp nbsp 否
2 nbsp nbsp nbsp nbsp nbsp 千克
3 nbsp nbsp nbsp nbsp nbsp gms
[编辑2]
query = "select Switch(qty=0,'2',qty<=rcvd_qty,'1',rcvd_qty=0,'2',qty>rcvd_qty,'3') as Status,item_type,catalogue,name,pd.rate,qty,pd.unit_code" _
& " from pur_det pd,itemhead th where pd.item_code=th.itemcode and order_no=0 order by catalogue"
adap1 = New OleDbDataAdapter(query, conn)
Dim saldet As New DataSet
adap1.Fill(saldet, "puritems")
Me.DataGridView1.DataSource = saldet.Tables(0)
DataGridView1.Columns.Item(0).HeaderText = "STATUS"
DataGridView1.Columns.Item(0).Width = 68
DataGridView1.Columns.Item(1).HeaderText = "TYPE"
DataGridView1.Columns.Item(1).Width = 60
DataGridView1.Columns.Item(2).HeaderText = "CATALOGUE"
DataGridView1.Columns.Item(2).Width = 140
DataGridView1.Columns.Item(3).HeaderText = "DESCRIPTION"
DataGridView1.Columns.Item(3).Width = 300
DataGridView1.Columns.Item(4).HeaderText = "RATE"
DataGridView1.Columns.Item(4).Width = 60
DataGridView1.Columns.Item(5).HeaderText = "QUANTITY"
DataGridView1.Columns.Item(5).Width = 84
DataGridView1.Columns.Item(6).HeaderText = "UNIT" ' this column is removed below because it only had primary key values of this table("unitmast").
DataGridView1.Columns.Item(6).Width = 70
adap1 = New OleDbDataAdapter("select * from unitmast order by unitcode ASC", conn)
Dim unitc As New DataSet
adap1.Fill(unitc, "unitmast")
Me.DataGridView1.Columns.RemoveAt(6) 'here the same is added with display member to view its actual value
Dim uncol As New DataGridViewComboBoxColumn
With uncol
.Name = "unit_code"
.DataPropertyName = "unit_code"
.DataSource = unitc.Tables(0)
.ValueMember = "unitcode"
.DisplayMember = "desc"
.HeaderText = "UNIT"
.FlatStyle = FlatStyle.Flat
.DropDownWidth = 160
.Width = 70
End With
Me.DataGridView1.Columns.Insert(6, uncol)
DataGridViewComboBoxCell没有SelectedIndex或SelectedValue属性。
您可以像这样直接设置值：
CType(Me.DataGridView1("unit_code", e.RowIndex), DataGridViewComboBoxCell).Value = "your value string"
或者使用items集合的索引：（只有在没有设置ValueMember和DisplayMember属性的情况下，这才有效）
Dim combo As DataGridViewComboBoxCell
combo = CType(Me.DataGridView1("unit_code", e.RowIndex), DataGridViewComboBoxCell)
combo.Value = combo.Items('your index')
你也可以检查一个值，而不是像这样：
If Not Me.DataGridView1.Rows(e.RowIndex).Cells(2).Value Is Nothing Then
'Your code
End If
我为你编写并测试代码祝你好运：
Dim Dt As New DataTable
Sub CreateDT()
Dt.Columns.Add("Col1")
Dt.Columns.Add("Col2")
Dt.Rows.Add(New Object(1) {"1", "A"})
Dt.Rows.Add(New Object(1) {"2", "B"})
Dt.Rows.Add(New Object(1) {"3", "C"})
End Sub
Private Sub ChildRibbonForm_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load
CreateDT()
'
'Dim CellCol As DataGridViewComboBoxColumn = CType(DataGridView1.Columns(0), DataGridViewComboBoxColumn)
Dim CellCol As New DataGridViewComboBoxColumn
CellCol.Items.Add("Test1")
CellCol.Items.Add("Test2")
CellCol.Items.Add("Test3")
Me.DataGridView1.DataSource = Dt
Me.DataGridView1.Columns.Insert(0, CellCol)
Dim CellBox As DataGridViewComboBoxCell = CType(DataGridView1.Rows(1).Cells(0), DataGridViewComboBoxCell)
'Select the Second Item
CellBox.Value = CellCol.Items(1)
End Sub
'Declare datatable
Dim cdt as new Datatable
'Add columns with types. It is important you specify the type for value member column
cdt.Columns.Add("vm", System.Type.GetType("System.Int32"))
cdt.Columns.Add("dm", System.Type.GetType("System.String"))
'Add items to table
cdt.Rows.Add
cdt.Rows(0).Item(0) = 1
cdt.Rows(0).Item(1) = "Red Cat"
cdt.Rows.Add
cdt.Rows(1).Item(0) = 2
cdt.Rows(1).Item(1) = "Black Cat"
'Add datasource to DataGridViewComboBoxColumn
Dim cc As DataGridViewComboBoxColumn
cc = datagridview1.Columns('colIndex')
cc.DataSource = cdt
cc.ValueMember = "vm"
cc.DisplayMember = "dm"
'Setting then selected value is thus:
Datagridview1.Rows('rowIndex').Cells('colIndex').Value = 2 '2 for black cat
这适用于我