Dropdownlist in a repeater, selected index changed

2019-07-20 11:16发布

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I have a repeater with a dropdownlist in it. When a user changes its index, I would like a label to change its value. (the ddlSizes values come from a MySQL DB)

Sizes.aspx

<asp:DropDownList ID="ddlSizes" runat="server" AutoPostBack="True" DataSourceID="objdsSizes"  DataTextField="SizeName" DataValueField="SizeID" />

<asp:Label ID="lbldummy" runat="server" Text=""></asp:Label>

Sizes.aspx.vb

Protected Sub ddlSizes_SelectedIndexChanged(ByVal sender As Object, ByVal e As System.EventArgs) Handles ddlSizes.SelectedIndexChanged
    lbldummy = ddlSizes.value
End Sub

But the ddlSizes.SelectedIndexChanged isn't recognized. So the value of lbldummy won't change.

Any suggestions? Thank you.

3条回答
混吃等死
2楼-- · 2019-07-20 11:36

Here's an example (C# but easily adaptable to VB.NET). Notice how inside the DdlSizes_SelectedIndexChanged I use FindControl to find the corresponding label:

<%@ Page Language="C#" %>
<script type="text/c#" runat="server">
    protected void Page_Load(object sender, EventArgs e)
    {
        if (!IsPostBack)
        {
            rep.DataSource = Enumerable.Range(1, 5);
            rep.DataBind();
        }
    }

    protected void DdlSizes_SelectedIndexChanged(object sender, EventArgs e)
    {
        var ddl = (DropDownList)sender;
        var lbl = (Label)ddl.FindControl("lbldummy");
        lbl.Text = ddl.SelectedValue;
    }
</script>
<!DOCTYPE html>
<html>
<head id="Head1" runat="server">
    <title></title>
</head>
<body>
    <form id="Form1" runat="server">
        <asp:Repeater ID="rep" runat="server">
            <ItemTemplate>
                <asp:DropDownList ID="ddlSizes" runat="server" AutoPostBack="True" OnSelectedIndexChanged="DdlSizes_SelectedIndexChanged">
                    <asp:ListItem Value="1" Text="item 1" />
                    <asp:ListItem Value="2" Text="item 2" />
                    <asp:ListItem Value="3" Text="item 3" />
                </asp:DropDownList>
                <asp:Label ID="lbldummy" runat="server" />
            </ItemTemplate>
        </asp:Repeater>
    </form>
</body>
</html>
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beautiful°
3楼-- · 2019-07-20 11:51

You will want to create the handler for the DropDownList, within this you need to have code which will convert the sender into a DropDownList then get the parent control and convert it into the RepeaterItem. From this you can then reference any other controls within the RepeaterItem

Public Sub ddlSizes_SelectedIndexChanged(sender As Object, e As EventArgs)
    Dim ddlSizes As DropDownList = DirectCast(sender, DropDownList)
    Dim ri As RepeaterItem = DirectCast(ddlSizes.Parent, RepeaterItem)
    Dim lbldummy As Label = DirectCast(ri.FindControl("lbldummy"), Label)
    lbldummy.Text = ddlSizes.SelectedValue
End Sub

Then on your ddlSizes DropDownList add OnSelectedIndexChanged="ddlSizes_SelectedIndexChanged" and make sure it has AutoPostBack="True" set

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【Aperson】
4楼-- · 2019-07-20 11:59

Text is probably the default property, but I'd still specify it:

lbldummy.Text = ddlSizes.value

but for this, you really don't need to do a postback, you can accomplish this through Javascript as well. doing something like this:

<asp:DropDownList ID="ddlSizes" runat="server" onchange="return ddlSizes_change(this);" DataSourceID="objdsSizes"  DataTextField="SizeName" DataValueField="SizeID" />


function ddlSizes_change(dropdown)
{
     document.getElementById('<%= lbldummy.ClientID %>').innerHTML = 
         dropdown.options[myindex].value

    return true;
}
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