选择下拉列表的问题 [英] problem with selectedvalue of dropdownlist

问题描述

在下拉列表中选择一个值时，我会尝试将选定值

放在标签中，但我总是得到第一个值''a''。

EnableViewState默认设置为true，所以......我的代码出了什么问题？

谢谢

Chris


受保护的子Page_Load（ByVal发送者为对象，ByVal e As

System.EventArgs）处理Me.Load

Dim ddl As New DropDownList

Dim z As ListItem

Dim kz As String

ddl.AutoPostBack = True

form1.Controls.Add（ddl）


如果Page.IsPostBack那么

kz = ddl.SelectedValue

Label1.Text = kz

否则

z =新ListItem（a，a）

ddl.Items.Add（z）

z = New ListItem（" b"，" b"）

ddl.Items.Add（z）

z = New ListItem（" ; c"，" c"）

ddl.Items.Add（z）

结束如果

结束苏b

< form id =" form1" runat =" server">

< asp：Label ID =" Label1" RUNAT = QUOT;服务器" >< / asp：标签>

< / form>

Hi,

When choosing a value in the dropdownlist, i try to put that selectedvalue
in the label, but i always get the first value ''a''.
EnableViewState is by default set to true, so ... what''s wrong in my code?
Thanks
Chris

Protected Sub Page_Load(ByVal sender As Object, ByVal e As
System.EventArgs) Handles Me.Load
Dim ddl As New DropDownList
Dim z As ListItem
Dim kz As String
ddl.AutoPostBack = True
form1.Controls.Add(ddl)

If Page.IsPostBack Then
kz = ddl.SelectedValue
Label1.Text = kz
Else
z = New ListItem("a", "a")
ddl.Items.Add(z)
z = New ListItem("b", "b")
ddl.Items.Add(z)
z = New ListItem("c", "c")
ddl.Items.Add(z)
End If
End Sub
<form id="form1" runat="server">
<asp:Label ID="Label1" runat="server" ></asp:Label>
</form>

推荐答案

克里斯 < ss*@qsd.dcwrote in message

news：uT ************** @ TK2MSFTNGP05.phx.gbl ...

"Chris" <ss*@qsd.dcwrote in message
news:uT**************@TK2MSFTNGP05.phx.gbl...

在下拉列表中选择一个值时，我尝试在标签中放入选定值

，但我总是得到第一个值''a''。

EnableViewState默认设置为true，所以...我的代码有什么问题？

谢谢

克里斯


受保护的子页面_Load（ByVal发送者作为对象，ByVal e As

System.EventArgs）处理Me.Load

Dim ddl As New DropDownList

Dim z As ListItem

Dim kz As String

ddl.AutoPostBack = True

form1.Controls.Add（ddl）


如果Page.IsPostBack那么

kz = ddl.SelectedValue

Label1.Text = kz

否则

z =新ListItem（a，a）

ddl.Items.Add（z）

z = New ListItem（" b"，" b"）

ddl.Items.Add（z）

z = New ListItem（" c"，" c"）

ddl.Items.Add（z）

结束如果

End Sub


< form id =" form1" runat =" server">

< asp：Label ID =" Label1" RUNAT = QUOT;服务器" >< / asp：标签>

< / form>

Hi,

When choosing a value in the dropdownlist, i try to put that selectedvalue
in the label, but i always get the first value ''a''.
EnableViewState is by default set to true, so ... what''s wrong in my code?
Thanks
Chris

Protected Sub Page_Load(ByVal sender As Object, ByVal e As
System.EventArgs) Handles Me.Load
Dim ddl As New DropDownList
Dim z As ListItem
Dim kz As String
ddl.AutoPostBack = True
form1.Controls.Add(ddl)

If Page.IsPostBack Then
kz = ddl.SelectedValue
Label1.Text = kz
Else
z = New ListItem("a", "a")
ddl.Items.Add(z)
z = New ListItem("b", "b")
ddl.Items.Add(z)
z = New ListItem("c", "c")
ddl.Items.Add(z)
End If
End Sub
<form id="form1" runat="server">
<asp:Label ID="Label1" runat="server" ></asp:Label>
</form>

每次选择项目时都会重新创建下拉列表。由于你有自动补货功能，你应该使用SelectionChanged例程来获取信息.b
从中获取信息。为什么要在代码中创建下拉列表？


LS

You are recreating the dropdownlist every time you select an item. Since
you have AutoPostBack on you should be using a SelectionChanged routine to
pull the information from. Why are you creating the dropdown in code?

LS

将您的标签设置代码放入预先渲染事件或索引选择

更改了下拉框中的事件。


" Chris" < ss*@qsd.dcwrote in message

news：uT ************** @ TK2MSFTNGP05.phx.gbl ...

Put your label setting code in the pre-render event or the index select
changed event for the dropdown box.


"Chris" <ss*@qsd.dcwrote in message
news:uT**************@TK2MSFTNGP05.phx.gbl...

在下拉列表中选择一个值时，我尝试在标签中放入选定值

，但我总是得到第一个值''a''。

EnableViewState默认设置为true，所以...我的代码有什么问题？

谢谢

克里斯


受保护的子页面_Load（ByVal发送者作为对象，ByVal e As

System.EventArgs）处理Me.Load

Dim ddl As New DropDownList

Dim z As ListItem

Dim kz As String

ddl.AutoPostBack = True

form1.Controls.Add（ddl）


如果Page.IsPostBack那么

kz = ddl.SelectedValue

Label1.Text = kz

否则

z =新ListItem（a，a）

ddl.Items.Add（z）

z = New ListItem（" b"，" b"）

ddl.Items.Add（z）

z = New ListItem（" c"，" c"）

ddl.Items.Add（z）

结束如果

End Sub


< form id =" form1" runat =" server">

< asp：Label ID =" Label1" RUNAT = QUOT;服务器" >< / asp：标签>

< / form>

Hi,

When choosing a value in the dropdownlist, i try to put that selectedvalue
in the label, but i always get the first value ''a''.
EnableViewState is by default set to true, so ... what''s wrong in my code?
Thanks
Chris

Protected Sub Page_Load(ByVal sender As Object, ByVal e As
System.EventArgs) Handles Me.Load
Dim ddl As New DropDownList
Dim z As ListItem
Dim kz As String
ddl.AutoPostBack = True
form1.Controls.Add(ddl)

If Page.IsPostBack Then
kz = ddl.SelectedValue
Label1.Text = kz
Else
z = New ListItem("a", "a")
ddl.Items.Add(z)
z = New ListItem("b", "b")
ddl.Items.Add(z)
z = New ListItem("c", "c")
ddl.Items.Add(z)
End If
End Sub
<form id="form1" runat="server">
<asp:Label ID="Label1" runat="server" ></asp:Label>
</form>

感谢您的回复。

我事先并不知道我需要多少下拉列表。这是来自一个

数据库，所以我必须通过代码创建它们。

这样做，没有SelectionChanged程序可用......

Lloyd Sheen < [e-mail] in bericht

新闻：uV ************* @ TK2MSFTNGP02.phx.gbl ...

Thanks for replying.
I don''t know in advance how many dropdownlists i need. This is coming from a
database, so i have to create them by code.
Doing like this, there is no SelectionChanged procedure available ...
"Lloyd Sheen" <[e-mail] in bericht
news:uV*************@TK2MSFTNGP02.phx.gbl...

>

" Chris" < ss*@qsd.dcwrote in message

news：uT ************** @ TK2MSFTNGP05.phx.gbl ...

>
"Chris" <ss*@qsd.dcwrote in message
news:uT**************@TK2MSFTNGP05.phx.gbl...

>

当在下拉列表中选择一个值时，我会尝试将
selectedvalue放在标签中，但我总是得到第一个值''''。
默认情况下EnableViewState设置为true，所以......我的代码中有什么问题？
谢谢
Chris

受保护的子Page_Load（ByVal发送者作为对象，ByVal e As
System.EventArgs）处理Me.Load
Dim ddl作为新的DropDownList
Dim z作为ListItem
Dim kz As String
ddl.AutoPostBack = True
form1.Controls.Add（ddl）

如果Page.IsPostBack那么
kz = ddl.SelectedValue
Label1.Text = kz
Else
z = New ListItem（" a"，" a"）
ddl.Items.Add（z）
z = New ListItem（ b，b，ddl .Items.Add（z）
z = New ListItem（" c"，" c"）
ddl.Items.Add（z）
结束如果
End Sub

< form id =" form1" runat =" server">
< asp：Label ID =" Label1" RUNAT = QUOT;服务器" >< / asp：标签>
< / form>

>Hi,

When choosing a value in the dropdownlist, i try to put that
selectedvalue in the label, but i always get the first value ''a''.
EnableViewState is by default set to true, so ... what''s wrong in my
code?
Thanks
Chris

Protected Sub Page_Load(ByVal sender As Object, ByVal e As
System.EventArgs) Handles Me.Load
Dim ddl As New DropDownList
Dim z As ListItem
Dim kz As String
ddl.AutoPostBack = True
form1.Controls.Add(ddl)

If Page.IsPostBack Then
kz = ddl.SelectedValue
Label1.Text = kz
Else
z = New ListItem("a", "a")
ddl.Items.Add(z)
z = New ListItem("b", "b")
ddl.Items.Add(z)
z = New ListItem("c", "c")
ddl.Items.Add(z)
End If
End Sub
<form id="form1" runat="server">
<asp:Label ID="Label1" runat="server" ></asp:Label>
</form>

每次选择项目时都要重新创建下拉列表。由于你有自动补货功能，你应该使用SelectionChanged例程来获取信息.b
从中获取信息。你为什么要在代码中创建下拉列表？


LS

You are recreating the dropdownlist every time you select an item. Since
you have AutoPostBack on you should be using a SelectionChanged routine to
pull the information from. Why are you creating the dropdown in code?

LS

这篇关于选择下拉列表的问题的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！