C＃-如果数据库记录为空，如何从datagridview处理图片框

Question

I am trying to get images from my datagridview and got success, but if some records dont have image or (null), than i got error ( Unable to cast object of type 'System.DBNull' to type 'System.Byte[]'.). Following is my code:

 private void dgridEmployees_SelectionChanged(object sender, EventArgs e)
    {
        DataGridViewCell cell = null;
        foreach (DataGridViewCell selectedCell in dgridEmployees.SelectedCells)
        {
            cell = selectedCell;
            break;

        }

        if (cell != null)
        {
            DataGridViewRow row = cell.OwningRow;
            lbl_ID.Text = row.Cells[0].Value.ToString();
            tboxEmployeeID.Text = row.Cells[1].Value.ToString();
            tboxEmployeeName.Text = row.Cells[2].Value.ToString();
            dtboxJoiningDate.Text = row.Cells[3].Value.ToString();
            tboxDepartment.Text = row.Cells[4].Value.ToString();
            tboxPath.Text = row.Cells[5].Value.ToString();

            byte[] img = (byte[])dgridEmployees.CurrentRow.Cells[6].Value;
            if (img == null)
                pictureBox1.Image = null;
            else
            {
                MemoryStream ms = new MemoryStream(img);
                pictureBox1.Image = Image.FromStream(ms);
            }


        }

Please suggest any solution for my above code?

Answer 1

Firstly you need to check if the cell contains no value. In this case, it's value will be DBNull.Value (the single instance of the DBNull class). You can only convert its value to a byte[] if the comparison is false.

if (dgridEmployees.CurrentRow.Cells[6].Value != DBNull.Value)
{
    byte[] img = (byte[])dgridEmployees.CurrentRow.Cells[6].Value;
    MemoryStream ms = new MemoryStream(img);
    pictureBox1.Image = Image.FromStream(ms);
}
else
{
    pictureBox1.Image = null;
}