c# Linq中数据网格视图忽略的第一行

Question

我有一个程序，基本上是创建，读取，编辑和删除linq数据库。它在不同的行上运行得很好，但是当我选择第一行删除它时，它就像没有选择row一样，所以它返回给我一个"选择行"输出警告。

另外，当我单击第一行上的modify时，它总是只编辑它下面的行。(其他行不受影响)

这是类中的'event update'代码:-

 public int UpdateEvent(int selectedRow, string name, DateTime date, string eventType, string eventVenue)
    {
        EventTicketEntities database = new EventTicketEntities();
        Event selected = database.Events.Where(x => x.EventId == selectedRow).FirstOrDefault(); //selected row will give the id of the row
        if (selected == null)
        {
            return -1;
        }
        else
        {
            selected.EventName = name;
            selected.EventDate = date;
            selected.EventType = eventType;
            selected.EventVenue = eventVenue;
            return database.SaveChanges();
        }
    }

这是类中'事件删除'的代码:-

 public int DeleteEvent(int selectedRow)
    {
        EventTicketEntities database = new EventTicketEntities();
        Event eventDelete = database.Events.Where(x => x.EventId == selectedRow).FirstOrDefault();
        database.Events.Remove(eventDelete); //We use this method to delete the particular customer 
        return database.SaveChanges(); //returns the affected rows ....
    }

这是表单按钮的代码:-

  private void btnModify_Click(object sender, EventArgs e)
    {
        if (SelectedRow != -1) //if not selected do nothing
        {
            if (MessageBox.Show("Are you sure?", "Modify", MessageBoxButtons.YesNo, MessageBoxIcon.Stop) == DialogResult.Yes)
            {
                EventBL eBL = new EventBL();
                int result = eBL.UpdateEvent(SelectedRow, eventName.Text, calendar.Value, cmbEventType.SelectedValue.ToString(), cmbEventVenue.SelectedValue.ToString());
                 MessageBox.Show(result + " rows affected!" + SelectedRow);
                 dgvEvents.DataSource = eBL.GetEvents();
                 dgvEvents.Refresh();
            }
        }
        else
        {
            EventBL eBL = new EventBL();
            MessageBox.Show("Select Row first" + SelectedRow);
            dgvEvents.DataSource = eBL.GetEvents();
            dgvEvents.Refresh();
        }
    }

这是删除按钮的代码:-

 private void btnDelete_Click(object sender, EventArgs e)
    {
        if (SelectedRow != -1) //if not selected do nothing
        {
            if (MessageBox.Show("Are you sure?", "Delete", MessageBoxButtons.YesNo, MessageBoxIcon.Stop) == DialogResult.Yes)
            {
                EventBL eBL = new EventBL();
                int result = eBL.DeleteEvent(SelectedRow);
                MessageBox.Show(result + " rows affected!");
                dgvEvents.DataSource = eBL.GetEvents();
                SelectedRow = -1;
            }
        }
        else
        {
            MessageBox.Show("Select Row first");
        }
    }

数据网格视图的事件处理程序代码:-

 private void dgvEvents_CellClick(object sender, DataGridViewCellEventArgs e)
    {
        if (e.RowIndex > 0)
        {
            SelectedRow = int.Parse(dgvEvents[0, e.RowIndex].Value.ToString());
        }
    }

非常感谢你的帮助。

照顾-HurpaDerpa

Answer 1

顺便说一下，selected总是会得到一个不能为空的值所以条件是如果选择= = null)永远都是假的因为你赋值。firstdefault