为在同一列和同一行中验证先前的 DataGridViewTextBoxCell 后设置新的 DataGridViewComboBoxCell答案

【问题标题】：set new DataGridViewComboBoxCell for after validation of previous DataGridViewTextBoxCell in same column and row为在同一列和同一行中验证先前的 DataGridViewTextBoxCell 后设置新的 DataGridViewComboBoxCell
【发布时间】：2017-02-09 12:56:42
【问题描述】：

我有这个DataGridView，它有一个DataGridViewTextBoxColumn，用户可以在其中输入一个数字，在他输入后我执行搜索以查找该数字下的先前记录。

我想显示这些记录，以便用户可以选择其中一个，或者保留键入的值，这意味着他想创建一条新记录。

为此，我想在用户完成输入后将每个DataGridViewTextBoxCell 替换为DataGridViewComboBoxCell。

但是，当我尝试执行此替换时，它会引发此异常：System.Windows.Forms.dll 中的“System.InvalidOperationException”。附加信息：该操作无效，因为它导致重新进入对函数 SetCurrentCellAddressCore 的调用。

这是我的代码（我已经尝试处理 CellLeave 而不是 CellValidated）：

Private Sub DataGridViewDebitos_CellValidated(sender As Object, e As DataGridViewCellEventArgs) Handles DataGridViewDebitos.CellValidated
    DataGridViewDebitos.EndEdit(DataGridViewDataErrorContexts.Commit)
    If e.ColumnIndex = ColumnDebito.Index Then
        Dim cellDebito = DataGridViewDebitos.Rows(e.RowIndex).Cells(ColumnDebito.Index)
        Dim numDebito = String.Concat(If(cellDebito.Value, "").ToString.Where(Function(c) Char.IsLetterOrDigit(c)))
        If TypeOf cellDebito Is DataGridViewTextBoxCell AndAlso numDebito.Length >= 3 Then
            Dim prcsa As New List(Of JObject) 'In real version, prcsa is populated by an external function, but it doesn't affect the result
            Dim j = New JObject
            j.SetProperty("id", 0)
            j.SetProperty("nome", cellDebito.Value)
            prcsa.Insert(0, j) 'This option is always present, it allows user to keep simply what was typed
            'Exception hapens here
            DataGridViewDebitos(cellDebito.ColumnIndex, cellDebito.RowIndex) =
                New DataGridViewComboBoxCell With {
                    .DataSource = prcsa,
                    .DisplayMember = "nome",
                    .FlatStyle = FlatStyle.Flat,
                    .ValueMember = "id",
                    .Value = prcsa(0).Value(Of Integer)("id")}
        End If
    End If
End Sub

非常感谢

【问题讨论】：

标签： vb.net winforms datagridview datagridviewcomboboxcell datagridviewtextboxcell

【解决方案1】：

我已经通过 .BeginInvoke 将有问题的语句放入 Lambda 子程序中，这解决了问题，只是我不知道为什么......

谁能给我解释一下它的机制？谢谢！

Private Sub DataGridViewDebitos_CellValidated(sender As Object, e As DataGridViewCellEventArgs) Handles DataGridViewDebitos.CellValidated
    DataGridViewDebitos.EndEdit(DataGridViewDataErrorContexts.Commit)
    If e.ColumnIndex = ColumnDebito.Index Then
        Dim cellDebito = DataGridViewDebitos.Rows(e.RowIndex).Cells(ColumnDebito.Index)
        Dim numDebito = String.Concat(If(cellDebito.Value, "").ToString.Where(Function(c) Char.IsLetterOrDigit(c)))
        If TypeOf cellDebito Is DataGridViewTextBoxCell AndAlso numDebito.Length >= 3 Then
            Dim prcsa As New List(Of JObject) 'In real version, prcsa is populated by an external function, but it doesn't affect the result
            Dim j = New JObject
            j.SetProperty("id", 0)
            j.SetProperty("nome", cellDebito.Value)
            prcsa.Insert(0, j) 'This option is always present, it allows user to keep simply what was typed
            'Exception hapens here
            DataGridViewDebitos.BeginInvoke(
                Sub()
                    DataGridViewDebitos(cellDebito.ColumnIndex, cellDebito.RowIndex) =
                        New DataGridViewComboBoxCell With {
                        .DataSource = prcsa,
                        .DisplayMember = "nome",
                        .FlatStyle = FlatStyle.Flat,
                        .ValueMember = "id",
                        .Value = prcsa(0)("id")}
                End Sub)
        End If
    End If
End Sub

【讨论】：