使用实体框架用相应的项目填充 Gridview 内的 DropDownList

Question

protected void GridViewTicketHistory_RowDataBound(object sender, GridViewRowEventArgs e)
{
    if (e.Row.RowType == DataControlRowType.DataRow )
    {
        DropDownList drpnop = (DropDownList)e.Row.FindControl("DropDownList1");

        if (drpnop != null)
        {
            foreach (Ticket ticket in entities.Tickets) 
            {
                foreach (State state in entities.States)
                {
                    if (ticket.StateID == state.StateID)
                    {
                        drpnop.DataTextField = state.StateName;
                        drpnop.DataValueField = state.StateID.ToString();
                    }
                }  
            }

            drpnop.DataBind();
        }
    }
}

数据绑定

protected void editCustomerTicket()
{
    GridViewTicketHistory.AutoGenerateEditButton = true;

    DataTable dat = new DataTable();
    int ticketno = Convert.ToInt32(Session["TicketNo"]);

    var a = from employee in entities.Employees
            from ticket in employee.EmployeeTicket
            select new 
            {
                employee.ID,
                employee.Name,
                ticket.TicketNo,
                ticket.Subject,
                ticket.Date,
                ticket.State.StateName
            };

    GridViewTicketHistory.DataSource = a;
    GridViewTicketHistory.DataBind();
}

问题

我使用实体框架，我有 State 和 Tickets 表。Tickets 具有指向 State.(tickets.StateID).In 的导航属性 这段代码我试图查看每个下拉列表以及相应的状态 如果我使用 Command.Writeline 我可以看到 state.StateName 和 state.StateID 不是空的和正确的值。但是我看到是空的 填写下拉列表时的值。

我的目标

我的主要目标是在 下拉列表，但也可以从这些下拉列表中选择修复项目 下列表。假设 StateID=0 StateName=Started StateID=1 StateName=%25 progress StateID=2 StateName=finished 每个单独的工单都有状态 id 和 name 并希望根据它在所有行中显示它 票。也可以从 StateID= 0,1,2 的固定列表中选择。

Answer 1

您需要做的第一件事是在获取GridViewTicketHistory 的数据时避免使用匿名类型，因为您需要将e.Row.DataItem 转换回预定义类型以设置下拉列表的选定项。我会建议以下课程

public class TicketHistory
{
    public int ID { get; set; }
    public string Name { get; set; }
    public string TicketNo { get; set; }
    public string Subject { get; set; }
    public string Date { get; set; }
    public int? StateID { get; set; }
    public string StateName { get; set; }
}

如下更改editCustomerTicket 方法，使a 的类型变为List<TicketHistory> 而不是匿名类型。

protected void editCustomerTicket()
{
    GridViewTicketHistory.AutoGenerateEditButton = true;

    var a = (from employee in entities.Employees
            from ticket in employee.EmployeeTicket
            select new TicketHistory 
            {
                ID = employee.ID,
                Name = employee.Name,
                TicketNo = ticket.TicketNo,
                Subject = ticket.Subject,
                Date = ticket.Date,
                StateID = ticket.StateID,
                StateName = ticket.State.StateName
            }).ToList();

    GridViewTicketHistory.DataSource = a;
    GridViewTicketHistory.DataBind();

}

绑定下拉列表时，您必须在调用.DataBind() 之前设置DataSource 属性或使用循环添加Items 元素。下面的代码使用循环填充下拉列表项，并根据工单的 StateID 设置下拉列表的选定值。

protected void GridViewTicketHistory_RowDataBound(object sender, GridViewRowEventArgs e)
{
    if (e.Row.RowType == DataControlRowType.DataRow)
    {
        DropDownList drpnop = (DropDownList)e.Row.FindControl("DropDownList1");

        if (drpnop != null)
        {
            // populate drpnop items
            foreach (State state in entities.States)
            {
                drpnop.Items.Add(new ListItem(state.StateName, state.StateID.ToString()));
            }

            // set the selected value of drpnop according to StateID of the ticket
            TicketHistory data = (TicketHistory)e.Row.DataItem;
            if (drpnop.Items.FindByValue(data.StateID.ToString()) != null)
            {
                drpnop.Items.FindByValue(data.StateID.ToString()).Selected = true;
            }
        }
    }
}