c# - 找不到类型 'MyType' 的默认成员

Question

我正在使用 ObjectDataSource 将对象绑定(bind)到 GridView。在 OnRowDataBound 事件处理程序中，我试图确定某个按钮是否应该可见。当运行时遇到此语句时，它会触发“未找到类型‘保证’的默认成员”。错误:

lbDel.Visible = Not (e.Row.DataItem("BillingReady"))

绑定(bind)到 GridView 的我的对象类:

public class Pledges : System.Collections.CollectionBase
{
    public Pledge this[int index]
    {
        get { return ((Pledge)(List[index])); }
        set { List[index] = value; }
    }

    public int Add(Pledge pledge)
    {
        return List.Add(pledge);
    }
}

我的 promise 类:

public class Pledge
{
    public int PledgeID { get; set; }
    public int EventID { get; set; }
    public int SponsorID { get; set; }
    public int StudentID { get; set; }
    public decimal Amount { get; set; }
    public string Type { get; set; }
    public bool IsPaid { get; set; }
    public string EventName { get; set; }
    public DateTime EventDate { get; set; }
    public bool BillingReady { get; set; }
    public string SponsorName { get; set; }
    public int Grade_level { get; set; }
    public string StudentName { get; set; }
    public string NickName { get; set; }
    public int Laps { get; set; }
    public decimal PledgeSubtotal { get; set; }
}

我的 OnRowDataBound 事件处理程序:

Protected Sub PledgeGrid_OnRowDataBound(ByVal sender As Object, ByVal e As GridViewRowEventArgs)
    If (e.Row.RowType = DataControlRowType.DataRow) And _
      Not ((e.Row.RowState = DataControlRowState.Edit) Or ((e.Row.RowState = DataControlRowState.Alternate) And (e.Row.RowState = DataControlRowState.Edit))) Then
        Dim lbDel As LinkButton
        Dim lbEd As LinkButton
        lbDel = CType(e.Row.FindControl("lbDelete"), LinkButton)
        lbEd = CType(e.Row.FindControl("lbEdit"), LinkButton)

        If ((e.Row.RowState = DataControlRowState.Normal) Or (e.Row.RowState = DataControlRowState.Alternate)) Then
            lbDel.Visible = Not (e.Row.DataItem("BillingReady"))    '<-- Problem happens here
            lbEd.Visible = Not (e.Row.DataItem("BillingReady"))
        End If
    End If
End Sub

是的，我不得不混合使用 VB 和 C#，但我认为这不是问题所在。如果我理解 C# 等效于 VB 默认属性，则称为索引器。这不应该有资格作为索引器吗？

public Pledge this[int index]
{
    get { return ((Pledge)(List[index])); }
    set { List[index] = value; }
}

Answer 1

尝试将 DataItem 转换为 Pledge:

Dim pledge = DirectCast(e.Row.DataItem, Pledge)
lbDel.Visible = Not pledge.BillingReady