The XmlDataSource Control
The XmlDataSource control allows a data bound control to bind the data from a XML document. This control also supports XPath expressions that allows to return only certain nodes from the XML document.
Public Properties of XmlDataSource class
DataFile : Specifies the file name of an XML file that the data source binds to.
Advantage of XML File
- Its a Text file.
- Use for carry data.
- Build hierarchy of user defined tags.
- Best use in transformation.
The DropDownList Control
The DropDownList control displays the list of data as a drop-down list from which you can make a single selection. The DropDownList control exists within the System.Web.UI.WebControls namespace. You cannot select multiple items in this control because when you make a selection from the list, the list closes automatically.
The DropDownList control has no non-inherited methods or events. This class inherited the ListControl class.
Public Properties of DropDownList Class
SelectedIndex : Obtains or sets the index of the selected item in the control.
Application of DropDownList Control
- In Registration page where you can select your country in given DropDownList.
- In management project where you can select single option in given options.
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Lets take simple example
<%@ Page Language="C#" %>
<!DOCTYPE html>
<script runat="server">
protected void DropDownList1_SelectedIndexChanged(object sender, EventArgs e)
{
Label1.Text = "Your Selected Url is <br/>" + DropDownList1.SelectedValue;
}
</script>
<html xmlns="http://www.w3.org/1999/xhtml">
<head runat="server">
<title></title>
</head>
<body>
<form id="form1" runat="server">
<div>
<asp:DropDownList ID="DropDownList1" runat="server" AutoPostBack="True" DataSourceID="XmlDataSource1" DataTextField="Text" DataValueField="url" OnSelectedIndexChanged="DropDownList1_SelectedIndexChanged">
</asp:DropDownList>
<asp:XmlDataSource ID="XmlDataSource1" runat="server" DataFile="~/XMLFile.xml"></asp:XmlDataSource>
</div>
<asp:Label ID="Label1" runat="server"></asp:Label>
</form>
</body>
</html>
Output<!DOCTYPE html>
<script runat="server">
protected void DropDownList1_SelectedIndexChanged(object sender, EventArgs e)
{
Label1.Text = "Your Selected Url is <br/>" + DropDownList1.SelectedValue;
}
</script>
<html xmlns="http://www.w3.org/1999/xhtml">
<head runat="server">
<title></title>
</head>
<body>
<form id="form1" runat="server">
<div>
<asp:DropDownList ID="DropDownList1" runat="server" AutoPostBack="True" DataSourceID="XmlDataSource1" DataTextField="Text" DataValueField="url" OnSelectedIndexChanged="DropDownList1_SelectedIndexChanged">
</asp:DropDownList>
<asp:XmlDataSource ID="XmlDataSource1" runat="server" DataFile="~/XMLFile.xml"></asp:XmlDataSource>
</div>
<asp:Label ID="Label1" runat="server"></asp:Label>
</form>
</body>
</html>
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