如何防止从绑定到DataGridView的DataTable中删除最后一个DataRow时出错

本文关键字：删除 最后一个 DataRow 出错 DataTable 何防止 绑定 DataGridView | 更新日期: 2023-09-27 18:24:30

在我的WinForms应用程序中，按下按钮会触发以下逻辑：

    private void ExecuteSelectedConsoleCommand()
    {
        var commandsRow = GetCommandsRow();
        var consoleCommand = GetConsoleCommand(commandsRow);
        Task.Factory.StartNew(() =>
        {
            var runningCommandRow =
                  runtimeDataSet.RunningCommands.AddRunningCommandsRow(Guid.NewGuid(),
                  consoleCommand.OneLineDescription);
            consoleCommand.Run(null);
            runningCommandRow.Delete();
        });
    }

BindingSource用于让DataGridView自动更新自身。

到目前为止，如果没有下面的破解，我会收到一个错误，说"索引0无效"。

        // prevents error when removing last row from data bound datagridview
        var placeholder = runtimeDataSet
                             .RunningCommands
                             .AddRunningCommandsRow(Guid.NewGuid(), "PLACEHOLDER");

有了上面的代码，DataGridView中总是至少有一行，它就可以正常工作了。

我该如何解决这个问题？

注意：这似乎是许多其他人都会遇到的情况，但我的网络搜索失败了。。

如何防止从绑定到DataGridView的DataTable中删除最后一个DataRow时出错

我也遇到过同样的问题。经过一番尝试和错误之后，我发现你必须处理datagridview的几个事件才能消除这种情况，即使这样也需要一些错误忽略。我不记得我到底做了什么来避免这个错误，但我认为以下片段可能会提供一些见解（评论中的解释）：

删除行：

//When I remove a row that has been added, but not commited return from the function
//run the update function only if the row is commited (databound)
private void dgvTest_RowsRemoved(object sender, DataGridViewRowsRemovedEventArgs e) {
    if (_lastDataRow == null || _lastDataRow.RowState == DataRowState.Added)
        return;
    UpdateRowToDatabase();
}

行验证：

//I got the kind of Index not valid or other index errors
//RowValidating is fired when entering the row and when leaving it
//In my case there was no point in validating on row enter
private void dgvTest_RowValidating(object sender, DataGridViewCellCancelEventArgs e)    {
if (Disposing)
     return;
if (!dgvTest.IsCurrentRowDirty) {
     return;
    }
try {
var v = dgvTest.Rows[e.RowIndex].DataBoundItem;
} catch {
return;
}
}

数据错误：

//I had to trap some errors and change things accordingly
private void dgvTest_DataError(object sender, DataGridViewDataErrorEventArgs e) {
        if (e.Exception.Message.Contains("Index") && e.Exception.Message.Contains("does not have a value")) {
            //when editing a new row, after first one it throws an error
            //cancel everything and reset to allow the user to make the desired changes
            bindingSource.CancelEdit();
            bindingSource.EndEdit();
            bindingSource.AllowNew = false;
            bindingSource.AllowNew = true;
            e.Cancel = true;
            dgvTest.Visible = false;
            dgvTest.Visible = true;
        }
    }

行输入：

 //Some problemes occured when entering a new row
 //This resets the bindingsource's AllowNew property so the user may input new data
 private void dgvTest_RowEnter(object sender, DataGridViewCellEventArgs e) {
            if (!_loaded)
                return;
            if (e.RowIndex == dgvTest.NewRowIndex)
                if (String.IsNullOrWhiteSpace(dgvTest.Rows[e.RowIndex == 0 ? e.RowIndex : e.RowIndex - 1].Cells[_idColumn].Value.ToStringSafe())) {
                    bindingSource.CancelEdit();
                    bindingSource.AllowNew = false;
                    bindingSource.AllowNew = true;
                }
        }

希望这能有所帮助！

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