C＃LINQ錯誤，無法找出問題所在

Question

我所顯示的程序將顯示列表的內容。 菜單條中的不同項目允許用戶在單擊項目時在datagridview中看到相應的數據。 但是對於一個特定的列表，我可以選擇過濾結果。 單擊此項目時，將彈出一個對話框，允許用戶過濾其結果。 這可行，您可以繼續查看其他列表，然后單擊過濾器項嘗試新的搜索。 但是，當您首先使用或不使用過濾器進行過濾搜索時，而不是轉到另一個列表時，您使用或不使用過濾器進行另一個過濾搜索時，會出現我遇到的問題。 該錯誤實際上是在對話框第二次出現時發生的，而不是在您單擊接受該對話框的按鈕時發生的。

我收到的錯誤如下：

“在DataGridView中發生以下異常：System.IndexOutOfRangeException：索引0沒有值。在System.Windows.Forms.DatagridView.DataGridViewDataConnection.GetError（Int32 rowIndex）的System.Windows.Forms.CurrencyManager.ge_Item（Int32 index）處）要替換此默認對話框，請處理DataError事件。”

在錯誤中，有一部分會根據所選單元格在哪一行而變化。 根據該行，“索引0”將更改為“索引3”。

該部分的代碼如下：

private void mnusViewParagraphHistory_Click(object sender, EventArgs e)
    {
        ViewHistoryFilter histFilter = new ViewHistoryFilter();
        int idFilt;
        string fundIDFilt = "";
        string changedBFilt = "";

        parHRes.Clear();
        if (parH.Count != 0)
        {
            if (histFilter.ShowDialog(this) == DialogResult.OK)
            {
                var parahistQuery = from his in parH
                                    select his;

                if (histFilter.txtID.Text.Trim() != "")
                {
                    idFilt = Convert.ToInt32(histFilter.txtID.Text.Trim());
                    parahistQuery = parahistQuery.Where(h => h.ID == idFilt);
                }

                if (histFilter.txtFundID.Text.Trim() != "")
                {
                    fundIDFilt = histFilter.txtFundID.Text.Trim();
                    parahistQuery = parahistQuery.Where(h => h.FundID.Contains(fundIDFilt.Trim()));
                }

                if (histFilter.txtChangedBy.Text.Trim() != "")
                {
                    changedBFilt = histFilter.txtChangedBy.Text.Trim();
                    parahistQuery = parahistQuery.Where(h => h.ChangedBy.Contains(changedBFilt.Trim()));
                }

                parHRes.AddRange(parahistQuery);
            }

            if (dataGridView1.DataSource != parHRes)
            {
                dataGridView1.DataSource = parHRes;
            }
        }
    }

如果我執行與其他項目一起產生錯誤的相同操作，則不會復制該錯誤。 但是，其他項僅更改數據源，因為我不需要像這樣顯示的那樣進行過濾：

private void mnusViewParagraph_Click(object sender, EventArgs e)
    {
        if (dataGridView1.DataSource != parG)
        {
            dataGridView1.DataSource = parG;
        }
    }

我不知道在看了這么長時間后是否只是對真正的錯誤視而不見，但是如果有人可以提供幫助，將不勝感激。

編輯：

處理數據錯誤事件時，我發現錯誤上下文是顯示的內容，其中包含堆棧跟蹤給出的以下信息：

dataGridView1_DataError at offset 433 in file:line:column <filename unknown>:0:0
OnDataError at offset 370 in file:line:column <filename unknown>:0:0
OnDataErrorInternal at offset 47 in file:line:column <filename unknown>:0:0
GetError at offset 156 in file:line:column <filename unknown>:0:0
GetErrorText at offset 149 in file:line:column <filename unknown>:0:0
Paint at offset 179 in file:line:column <filename unknown>:0:0
PaintRows at offset 1551 in file:line:column <filename unknown>:0:0
PaintGrid at offset 675 in file:line:column <filename unknown>:0:0
OnPaint at offset 785 in file:line:column <filename unknown>:0:0
PaintWithErrorHandling at offset 161 in file:line:column <filename unknown>:0:0
WmPaint at offset 831 in file:line:column <filename unknown>:0:0
WndProc at offset 689 in file:line:column <filename unknown>:0:0
WndProc at offset 275 in file:line:column <filename unknown>:0:0
OnMessage at offset 19 in file:line:column <filename unknown>:0:0
WndProc at offset 49 in file:line:column <filename unknown>:0:0
DebuggableCallback at offset 100 in file:line:column <filename unknown>:0:0
DispatchMessageW at offset 0 in file:line:column <filename unknown>:0:0
System.Windows.Forms.UnsafeNativeMethods.IMsoComponentManager.FPushMessageLoop at offset 647 in file:line:column <filename unknown>:0:0
RunMessageLoopInner at offset 364 in file:line:column <filename unknown>:0:0
RunMessageLoop at offset 97 in file:line:column <filename unknown>:0:0
RunDialog at offset 51 in file:line:column <filename unknown>:0:0
ShowDialog at offset 911 in file:line:column <filename unknown>:0:0
mnusViewParagraphHistory_Click at offset 273 in file:line:column <filename unknown>:0:0
RaiseEvent at offset 115 in file:line:column <filename unknown>:0:0
OnClick at offset 70 in file:line:column <filename unknown>:0:0
HandleClick at offset 201 in file:line:column <filename unknown>:0:0
HandleMouseUp at offset 520 in file:line:column <filename unknown>:0:0
FireEventInteractive at offset 137 in file:line:column <filename unknown>:0:0
FireEvent at offset 280 in file:line:column <filename unknown>:0:0
OnMouseUp at offset 178 in file:line:column <filename unknown>:0:0
OnMouseUp at offset 38 in file:line:column <filename unknown>:0:0
WmMouseUp at offset 721 in file:line:column <filename unknown>:0:0
WndProc at offset 2362 in file:line:column <filename unknown>:0:0
WndProc at offset 42 in file:line:column <filename unknown>:0:0
WndProc at offset 74 in file:line:column <filename unknown>:0:0
WndProc at offset 54 in file:line:column <filename unknown>:0:0
OnMessage at offset 19 in file:line:column <filename unknown>:0:0
WndProc at offset 49 in file:line:column <filename unknown>:0:0
DebuggableCallback at offset 100 in file:line:column <filename unknown>:0:0
DispatchMessageW at offset 0 in file:line:column <filename unknown>:0:0
System.Windows.Forms.UnsafeNativeMethods.IMsoComponentManager.FPushMessageLoop at offset 647 in file:line:column <filename unknown>:0:0
RunMessageLoopInner at offset 364 in file:line:column <filename unknown>:0:0
RunMessageLoop at offset 97 in file:line:column <filename unknown>:0:0
Run at offset 49 in file:line:column <filename unknown>:0:0
Main at offset 77 in file:line:column <filename unknown>:0:0
_nExecuteAssembly at offset 0 in file:line:column <filename unknown>:0:0
ExecuteAssembly at offset 109 in file:line:column <filename unknown>:0:0
RunUsersAssembly at offset 42 in file:line:column <filename unknown>:0:0
ThreadStart_Context at offset 99 in file:line:column <filename unknown>:0:0
Run at offset 176 in file:line:column <filename unknown>:0:0
Run at offset 44 in file:line:column <filename unknown>:0:0
ThreadStart at offset 68 in file:line:column <filename unknown>:0:0

重復3次，如果您接受對話框，對話框將繼續運行而不會停止。

Answer 1

我已經知道了問題所在。 發生錯誤的點在直線上

parHRes.Clear();

datagridview不喜歡用作數據源的列表現在為空。 在它之前添加一行以將數據源更改為其他內容可以解決此問題。