上传和下载按钮不适用于我的数据库的第三和第四列

Question

我正在使用Microsoft visual studio 2010在C＃中开发一个Windows窗体应用程序。我有一个下载和上传按钮，用于将文件附加到我的本地数据库（网格视图）。我的第二列细胞没问题。但是当上传附件到第三和第四列单元格时，我无法附加和下载文件。你怎么看？我是否也需要这些列的单独按钮。或者，您能否告诉我如何使用表单中的相同按钮上传和下载文件。

我可以将文件附加到第3和第4列，请参阅快照的链接。 http://i60.tinypic.com/xbe0bo.jpg

代码低于

 using System;
 using System.Collections.Generic;
 using System.ComponentModel;
 using System.Data;
 using System.Drawing;
 using System.Linq;
 using System.Text;
 using System.Windows.Forms;
 using System.IO;



  private void Form1_Load(object sender, EventArgs e)

   {

    // TODO: This line of code loads data into the 'cncDataSet1.CncInfo' table. You can move, or remove it, as needed.

    this.cncInfoTableAdapter.Fill(this.cncDataSet1.CncInfo);

    timer1.Start();

   }

private void btnUpload_Click(object sender, EventArgs e)

{

    try

    {

        //Throw error if attachment cell is not selected.

        //make sure user select only single cell

        if (cncInfoDataGridView.SelectedCells.Count == 1 && cncInfoDataGridView.SelectedCells[0].ColumnIndex == 1)

        {

            UploadAttachment(cncInfoDataGridView.SelectedCells[0]);

        }

        else if (cncInfoDataGridView.SelectedCells.Count == 1 && cncInfoDataGridView.SelectedCells[1].ColumnIndex == 2)

        {

            UploadAttachment(cncInfoDataGridView.SelectedCells[1]);

        }

        else if (cncInfoDataGridView.SelectedCells.Count == 1 && cncInfoDataGridView.SelectedCells[2].ColumnIndex == 3)

        {

            UploadAttachment(cncInfoDataGridView.SelectedCells[2]);

        }

        else

            MessageBox.Show("Select a single cell from Attachment column", "Error uploading file", MessageBoxButtons.OK, MessageBoxIcon.Error);

    }

    catch (Exception ex)

    {

        MessageBox.Show(ex.Message, "Error uploading file", MessageBoxButtons.OK, MessageBoxIcon.Error);

    }

}



private void btnDownload_Click(object sender, EventArgs e)

{

    //Throw error if attachment cell is not selected.

    //make sure user select only single cell

    //and the cell have a value in it

    if (cncInfoDataGridView.SelectedCells.Count == 1 &&     cncInfoDataGridView.SelectedCells[0].ColumnIndex == 1 && cncInfoDataGridView.SelectedCells[0].Value != null)

    {

        DownloadAttachment(cncInfoDataGridView.SelectedCells[0]);

    }

    else if (cncInfoDataGridView.SelectedCells.Count == 1 && cncInfoDataGridView.SelectedCells[1].ColumnIndex == 2 && cncInfoDataGridView.SelectedCells[1].Value != null)

    {

        DownloadAttachment(cncInfoDataGridView.SelectedCells[1]);

    }

    else if (cncInfoDataGridView.SelectedCells.Count == 1 && cncInfoDataGridView.SelectedCells[2].ColumnIndex == 3 && cncInfoDataGridView.SelectedCells[2].Value != null)

    {

        DownloadAttachment(cncInfoDataGridView.SelectedCells[2]);

    }

    else

        MessageBox.Show("Select a single cell from Attachment column", "Error uploading file", MessageBoxButtons.OK, MessageBoxIcon.Error);

}



private void cncInfoDataGridView_CellDoubleClick(object sender, DataGridViewCellEventArgs e)

{

    //Throw error if attachment cell is not selected.

    //make sure user select only single cell

    //and the cell have a value in it

    if (cncInfoDataGridView.SelectedCells.Count == 1 && cncInfoDataGridView.SelectedCells[0].ColumnIndex == 1 && cncInfoDataGridView.SelectedCells[0].Value != null)

    {

        DownloadAttachment(cncInfoDataGridView.SelectedCells[0]);

    }

    else if (cncInfoDataGridView.SelectedCells.Count == 1 && cncInfoDataGridView.SelectedCells[0].ColumnIndex == 2 && cncInfoDataGridView.SelectedCells[1].Value != null)

    {

        DownloadAttachment(cncInfoDataGridView.SelectedCells[1]);

    }

    else if (cncInfoDataGridView.SelectedCells.Count == 1 && cncInfoDataGridView.SelectedCells[2].ColumnIndex == 3 && cncInfoDataGridView.SelectedCells[2].Value != null)

    {

        DownloadAttachment(cncInfoDataGridView.SelectedCells[2]);

    }

    else

      MessageBox.Show("Select a single cell from Attachment column", "Error   uploading file", MessageBoxButtons.OK, MessageBoxIcon.Error);

}

        }

    }

}

}}

Answer 1

我在这里看到的一个问题是这些条件：

cncInfoDataGridView.SelectedCells.Count == 1 && cncInfoDataGridView.SelectedCells[1].ColumnIndex == 2

如果您希望只选择一个单元格（SelectedCells.Count == 1），那么就不会有SelectedCells[1]或SelectedCells[2]等......总是{ {1}}。

因此，只需在要引用所选单元格的每个位置使用SelectedCells[0]（因为您只需要选择一个单元格）。

编辑：顺便说一下，我建议您通过编写如下函数来清理您的代码：

SelectedCells[0]

然后在所有条件下使用：

private bool SelectedNonNullCellFromColumn(int columnId)
{
    return cncInfoDataGridView.SelectedCells.Count == 1 && 
            cncInfoDataGridView.SelectedCells[0].ColumnIndex == columnId 
            && cncInfoDataGridView.SelectedCells[0].Value != null
}

（上传的条件有些不同，因为它们不会检查空值，因此你可以为那些创建类似的功能）

edit2 实际上，您不需要这样做。解决原始问题后，所有if(SelectedNonNullCellFromColumn(1)) { DownloadAttachment(cncInfoDataGridView.SelectedCells[0]); } ，Download()内部条件将始终作用于Upload()因此您可以将所有条件合并为：

SelectedCells[0]