c# - 使用 vb 返回 IEnumerable 时，Asp.net 4.5 模型绑定(bind)中断？

Question

我有一个 GridView 如下:

<asp:GridView ID="gv" runat="server" SelectMethod="gv_GetData" AllowPaging="true" AllowSorting="true" AutoGenerateColumns="true">
</asp:GridView>

我在 c# 中有以下有效的代码:

public IList<string> gv_GetData(int maximumRows, int startRowIndex, out int totalRowCount, string sortByExpression)
{
    List<string> l = GetTestData();
    totalRowCount = l.Count;
    return l;
}

private List<string> GetTestData()
{
    List<string> l = new List<string>();
    l.Add("a");
    l.Add("b");
    l.Add("c");
    return l;
}

现在，在 VB 中我有:

Public Function gv_GetData(maximumRows As Integer, startRowIndex As Integer, ByRef totalRowCount As Integer, sortByExpression As String) As IList(Of String)
    Dim l As List(Of String) = GetTestData()
    totalRowCount = l.Count
    Return l
End Function

Private Function GetTestData() As List(Of String)
    Dim l As New List(Of String)()
    l.Add("a")
    l.Add("b")
    l.Add("c")
    Return l
End Function

VB 版本总是产生以下错误:

When the DataBoundControl has paging enabled, either the SelectMethod should return an IQueryable or should have all these mandatory parameters : int startRowIndex, int maximumRows, out int totalRowCount

这可能是框架错误吗？还是我漏掉了一些过于明显的东西？

---

下面由 nemesv 回答。新方法是:

Public Function gv_GetData(maximumRows As Integer, startRowIndex As Integer, <System.Runtime.InteropServices.Out()> ByRef totalRowCount As Integer, sortByExpression As String) As IList(Of String)
    Dim l As List(Of String) = GetTestData()
    totalRowCount = l.Count
    Return l
End Function

Answer 1

您需要用 OutAttribute 标记 totalRowCount

<Out()> ByRef totalRowCount As Integer

这在语义上等同于 c# out 关键字。