Question

我正在处理的应用程序是Service Desk App。我有一个表单，它使用DropDownList，其中包含来自Active Directory的员工姓名。任何员工都可以提出请求并保存。

当员工离开公司并因此从Active Directory中删除其帐户时出现问题。当某个其他员工搜索数据库以查找可能属于他的相关服务票证时，当尝试打开它时会抛出一个错误，指示该名称在DropDownList项目中不存在。

我需要的是一个解决方案，以便功能保持不变（能够删除Active Directory条目），但不会抛出任何错误。

我正在使用标签，ASP.NET和VB。 C＃的解决方案也很受欢迎。

提前感谢您对我的问题的建议。

更新：

我正在添加一些代码，以便更清晰。

ASPX :(这个很大，我只提出DropDownList）

<asp:FormView ID="FormView1" runat="server" DataSourceID="SqlDataSource1" 
        DataKeyNames="ITRequestId">
        <EditItemTemplate>
            <br />
            <asp:LinkButton ID="LinkButton5" runat="server" CausesValidation="True" 
                CommandName="Update" Text="Update" CssClass="InsertLink" />
            &nbsp;&nbsp;&nbsp;<asp:LinkButton ID="LinkButton6" runat="server" 
                CausesValidation="False" CommandName="Cancel" Text="Cancel" CssClass="CancelLink" />

                    ........    

                    <div id="user" style="float: left;">
                        <label>User:<asp:RequiredFieldValidator ID="RequiredFieldValidator9" runat="server" ErrorMessage="User" Display="Dynamic" ControlToValidate="DropDownList5" Text="*" ForeColor="#FF0000"></asp:RequiredFieldValidator></label><br />
                        <asp:DropDownList ID="DropDownList5" runat="server" SelectedValue='<%# Bind("ITRequestUserName") %>'>
                            <asp:ListItem Value=""></asp:ListItem>
                            <asp:ListItem Value="All">All</asp:ListItem>
                            <asp:ListItem Value="NA">N/A</asp:ListItem>
                        </asp:DropDownList>
                    </div>

                    .........
        </EditItemTemplate>

代码后面的vb :(这是巨大的，但我将页面加载事件放在引发错误的位置）

Protected Sub Page_Load(ByVal sender As Object, ByVal e As System.EventArgs) Handles Me.Load
    If (Not IsPostBack) Then
        If Request.UrlReferrer IsNot Nothing Then
            ViewState("RefUrl") = Request.UrlReferrer.ToString()
        End If
    End If
    'Handles the mode of the FormView according to the request
    If Request.QueryString.Get("ITRequestId") IsNot Nothing Then
        FormView1.DefaultMode = FormViewMode.ReadOnly
        Dim tName As String = DirectCast(FormView1.Row.FindControl("DropDownList5"), DropDownList).SelectedValue
        Dim temptype As String = DirectCast(FormView1.Row.FindControl("DropDownList1"), DropDownList).SelectedItem.Text
        Dim myAD As New tActiveDirectory(LDAPpath)
        Dim lName As String = HttpContext.Current.User.Identity.Name.ToString()
        Dim sDisplayName As String = myAD.GetUserInfo(lName, "displayName")
        Dim cName As String = DirectCast(FormView1.Row.FindControl("Label5"), Label).Text
        If Not (User.IsInRole("Developers") Or User.IsInRole("Administrators") Or tName = sDisplayName Or cName = sDisplayName) Then
            If (temptype = "Access rights") Then
                Response.Redirect("../IT/ITAccessDenied.aspx")
            End If
        End If
        If Not (User.IsInRole("Developers") Or User.IsInRole("Administrators") Or cName = sDisplayName) Then
            If (temptype = "Account") Then
                Response.Redirect("../IT/ITAccessDenied.aspx")
            End If
        End If
        If Not (User.IsInRole("LocalIT")) Then
            If (temptype = "Internal IT Task") Then
                Response.Redirect("../IT/ITAccessDenied.aspx")
            End If
        End If
    Else
        FormView1.DefaultMode = FormViewMode.Insert
        Dim tempstatus As DropDownList = DirectCast(FormView1.Row.FindControl("DropDownList2"), DropDownList)
        tempstatus.SelectedIndex = 3
    End If
End Sub

在声明tName变量时，代码的第11行会抛出错误。而且这种情况正在发生，因为数据库中将被DropDownList限制的UserName已从ActiveDirectory中删除，因此它不存在于List的值中。

以下是填充DropDownList的代码：

Protected Sub FormView1_ItemCreated(ByVal sender As Object, ByVal e As System.EventArgs) Handles FormView1.ItemCreated
    Dim d1 As DropDownList
    Dim d2 As DropDownList
    Dim myAD As New tActiveDirectory(LDAPpath)
    Dim users As New ArrayList()
    users = myAD.GetAllUsersInfo()
    d1 = DirectCast(FormView1.Row.FindControl("DropDownList5"), DropDownList)
    d2 = DirectCast(FormView1.Row.FindControl("DropDownList7"), DropDownList)
    d1.DataSource = users
    d2.DataSource = users
End Sub

Public Function GetAllUsersInfo() As ArrayList
        Dim Users As New ArrayList()
        Dim myDirectory As New DirectoryEntry(sPath)
        Dim mySearcher As New DirectorySearcher(myDirectory)
        Dim fullName As String
        mySearcher.Filter = "(&(objectCategory=person)(objectClass=user))"
        mySearcher.PropertiesToLoad.Add("sn")
        mySearcher.PropertiesToLoad.Add("displayName")
        mySearcher.Sort.PropertyName = "sn"
        mySearcher.Sort.Direction = SortDirection.Ascending
        Users.Add("")
        Users.Add("N/A")
        Users.Add("All")
        For Each result As DirectoryServices.SearchResult In mySearcher.FindAll
            fullName = result.Properties("displayName")(0).ToString
            Users.Add(fullName)
        Next
        Return Users
    End Function

任何有关此的帮助将不胜感激。谢谢。

Answer 1

您的问题没有太多关于代码的细节。但听起来你的应用程序试图在DDL中选择一个不存在的值（不再）了。在选择之前检查一下：

Dim ddl As DropDownList
Dim item As ListItem = ddl.Items.FindByValue("Kostopoulos")
If item IsNot Nothing Then
  ddl.SelectedIndex = ddl.Items.IndexOf(item)
Else
  ddl.Items.Add(New ListItem("Not available"))
  ddl.Enabled = False
End If

Answer 2

首先你应该从Dropdownlist中找到listitem，如

  ListItem li=DropdownID.Items.FindByValue("");
  if (li != null)
  DropdownID.SelectedValue = li.Value;

有关详细信息，请参阅msdn

当ListItem不再存在时，DropDownList会引发错误

2 个答案: