看起来像这个问题was addressed here,但他的解决方案并不适用于我。我创建了一个动态下拉菜单系统,该系统使用基于第一个下拉列表中所选项目的查询结果填充辅助下拉列表。DropDownList SelectedIndex值在AutoPostback上未更新
第一个下拉列表填充得到:得到填充
Dim db As New linqclassesDataContext
Dim categories = (From c In db.faq_cats)
NewFaqDropDownCategory.DataSource = categories
NewFaqDropDownCategory.DataTextField = "category"
NewFaqDropDownCategory.DataValueField = "category_id"
NewFaqDropDownCategory.DataBind()
Unset(categories)
Unset(db)
第二个下拉:
Protected Sub NewFaqDropDownCategory_SelectedIndexChanged(ByVal sender As Object, ByVal e As System.EventArgs)
Dim temp As Integer = CInt(Val(NewFaqDropDownCategory.SelectedIndex))
MsgBox(theDrop.SelectedValue)
Return
'Dim db As New linqclassesDataContext
'Dim faqs = (From f In db.faqs Where f.category = NewFaqDropDownCategory.SelectedValue)
'NewFaqDropDownList.DataSource = faqs
'NewFaqDropDownList.DataTextField = "question"
'NewFaqDropDownList.DataValueField = "id"
'NewFaqDropDownList.DataBind()
'NewFaqLabel.Visible = True
'NewFaqDropDownList.Visible = True
'Unset(faqs)
'Unset(db)
End Sub
第一个下拉的标记......
<asp:DropDownList ID="NewFaqDropDownCategory" AutoPostBack="true" runat="server" OnSelectedIndexChanged="NewFaqDropDownCategory_SelectedIndexChanged">
</asp:DropDownList>
而第二...
<asp:DropDownList ID="NewFaqDropDownList" runat="server" Visible="false">
</asp:DropDownList>
无论我尝试了什么,我总是会得到“1”(第二个下拉列表中第一项的值)。我之前引用的文章说这与AutoPostBack有关,服务器不知道该列表已更新。
任何人都可以澄清这一点对我来说多一点?
啊哈!你是完全正确的。我把休息放在那里,发现事情在事件发生之前确实被调用了。我将DataBind封装在if.page.ispostback条件中,并且解决了它!谢谢! – Anders 2009-03-03 20:31:36