ASP.NET Textbox DropDownExtender

Question

ASP.NET Textbox DropDownExtender

16.7k views Asked by Troy Mitchel At 02 March 2011 at 17:33

How to get the value from the dropdown to return to the TextBox? The following does not work. You can select the item from list though.

<body>
<form id="form1" runat="server">
<script type="text/javascript">
    function pageLoad() {
        //Same Width
        $get('ListBox1').style.width = $get('TextBox1').clientWidth;
    }
</script>
<ajax:ToolkitScriptManager ID="ToolkitScriptManager1" runat="server">
</ajax:ToolkitScriptManager>
<div>
    <asp:TextBox ID="TextBox1" runat="server"></asp:TextBox>
    <ajax:DropDownExtender ID="TextBox1_DropDownExtender" DropDownControlID="ListBox1"
        runat="server" DynamicServicePath="" Enabled="True" TargetControlID="TextBox1"
        HighlightBackColor="WhiteSmoke">
    </ajax:DropDownExtender>
</div>
<asp:ListBox ID="ListBox1" runat="server" AutoPostBack="True">
    <asp:ListItem>Item 1</asp:ListItem>
    <asp:ListItem>Item 2</asp:ListItem>
    <asp:ListItem>Item 3</asp:ListItem>
</asp:ListBox>
</form>

Original Q&A

There are 2 answers

Dillie-O On 02 March 2011 at 18:08

You'll want to wire up the onchange event to your ListItem to call a JavaScript method that gets the text from the item that was selected. Your JavaScript code would look something like this (not tested):

    function setOptionText()
    {
       var ddl = $get('ListBox1');
       var index = ddl.selectedIndex

       $get('TextBox1').value = ddl.options[index].value;
    }

Then you wire up your ListBox control accordingly. Note that you no longer need the AutoPostBack option since JavaScript is handling setting the text.

<asp:ListBox ID="ListBox1" runat="server" onchange="return setOptionText()">

**PhilPursglove** · Accepted Answer · 2011-03-02 18:08:56

You can put the selected item's text into the TextBox if you add a handler for the ListBox's SelectedIndexChanged event:

Markup:

<div>
    <asp:TextBox ID="TextBox1" runat="server"></asp:TextBox>    
    <ajaxtoolkit:dropdownextender id="TextBox1_DropDownExtender" dropdowncontrolid="ListBox1"
        runat="server" enabled="True" targetcontrolid="TextBox1"
        highlightbackcolor="WhiteSmoke" />
</div>
<asp:ListBox ID="ListBox1" runat="server" AutoPostBack="True" OnSelectedIndexChanged="ListBox_SelectedIndexChanged">
    <asp:ListItem>Item 1</asp:ListItem>
    <asp:ListItem>Item 2</asp:ListItem>
    <asp:ListItem>Item 3</asp:ListItem>
</asp:ListBox>

Code:

protected void ListBox_SelectedIndexChanged(object sender, EventArgs e)
{
    TextBox1.Text = ListBox1.SelectedItem.Text;
}

However, this could get really problematic to manage if you have a number of TextBoxes, Extenders and ListBoxes on the page so you might want to consider wrapping the TextBox, Extender and ListBox all up together in a UserControl.

TechQA.

ASP.NET Textbox DropDownExtender

There are 2 answers

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