Filtering Data Using the XmlDataSource Control

Filtering Data Using the XmlDataSou...

This page is specific to

Microsoft Visual Studio 2005/.NET Framework 2.0

Other versions are also available for the following:

ASP.NET

Filtering Data Using the XmlDataSource Control

You can filter the XML data exposed by an XmlDataSource control by setting the control's XPath property to an XPath filtering expression. If you have specified an Extensible Stylesheet Language (XSL) style sheet to transform the data exposed by your XmlDataSource control, the XPath filtering expression is applied after the transformation takes place.

The following code example shows an XmlDataSource control bound to a TreeView control. The XML data is filtered using an XPath query.

Visual Basic

<%@ Page Language="VB" %>
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">

<script runat="server">

Sub SelectRegion(sender As Object, e As EventArgs)
  If RegionDropDownList.SelectedValue = "(Show All)" Then
    PeopleDataSource.XPath = "/People/Person"
  Else
    Dim selectedValue As String = ""

    Select Case RegionDropDownList.SelectedValue
      Case "CA"
        selectedValue = "CA"
      Case "HI"
        selectedValue = "HI"
      Case "WA"
        selectedValue = "WA"
      Case Else
        ' Invalid value.
    End Select

    PeopleDataSource.XPath = "/People/Person[Address/Region='" & selectedValue & "']"
  End If

  PeopleTreeView.DataBind()
End Sub

</script>

<html  >
  <head runat="server">
    <title>ASP.NET Example</title>
</head>
<body>
    <form id="form1" runat="server">
      <table border="0" cellpadding="3">
        <tr>
          <td valign="top">
            <b>Select Region:</b>
            <asp:DropDownList runat="server" id="RegionDropDownList" AutoPostBack="True"
                              OnSelectedIndexChanged="SelectRegion">                              
              <asp:ListItem Selected="True">(Show All)</asp:ListItem>
              <asp:ListItem>CA</asp:ListItem>
              <asp:ListItem>HI</asp:ListItem>
              <asp:ListItem>WA</asp:ListItem>
            </asp:DropDownList>
          </td>
          <td valign="top">
            <asp:XmlDataSource
              id="PeopleDataSource"
              runat="server"
              XPath="/People/Person"
              DataFile="~/App_Data/people.xml" />

            <asp:TreeView
              id="PeopleTreeView"
              runat="server"
              DataSourceID="PeopleDataSource">
              <DataBindings>
                <asp:TreeNodeBinding DataMember="LastName"    TextField="#InnerText" />
                <asp:TreeNodeBinding DataMember="FirstName"   TextField="#InnerText" />
                <asp:TreeNodeBinding DataMember="Street"      TextField="#InnerText" />
                <asp:TreeNodeBinding DataMember="City"        TextField="#InnerText" />
                <asp:TreeNodeBinding DataMember="Region"      TextField="#InnerText" />
                <asp:TreeNodeBinding DataMember="ZipCode"     TextField="#InnerText" />
                <asp:TreeNodeBinding DataMember="Title"       TextField="#InnerText" />
                <asp:TreeNodeBinding DataMember="Description" TextField="#InnerText" />
              </DataBindings>
            </asp:TreeView>
          </td>
        </tr>
      </table>
    </form>
  </body>
</html>

<%@ Page Language="C#" %>
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">

<script runat="server">

void SelectRegion(object sender, EventArgs e)
{
  if (RegionDropDownList.SelectedValue == "(Show All)")
    PeopleDataSource.XPath = "/People/Person";
  else
  {
    string selectedValue = "";

    switch (RegionDropDownList.SelectedValue)
    {
      case "CA":
        selectedValue = "CA";
        break;
      case "HI":
        selectedValue = "HI";
        break;
      case "WA":
        selectedValue = "WA";
        break;
      default:
        // Invalid value.
        break;
    }

    PeopleDataSource.XPath = "/People/Person[Address/Region='" + selectedValue + "']";
  }

  PeopleTreeView.DataBind();
}

</script>

<html  >
  <head runat="server">
    <title>ASP.NET Example</title>
</head>
<body>
    <form id="form1" runat="server">
      <table border="0" cellpadding="3">
        <tr>
          <td valign="top">
            <b>Select Region:</b>
            <asp:DropDownList runat="server" id="RegionDropDownList" AutoPostBack="True"
                              OnSelectedIndexChanged="SelectRegion">                              
              <asp:ListItem Selected="True">(Show All)</asp:ListItem>
              <asp:ListItem>CA</asp:ListItem>
              <asp:ListItem>HI</asp:ListItem>
              <asp:ListItem>WA</asp:ListItem>
            </asp:DropDownList>
          </td>
          <td valign="top">
            <asp:XmlDataSource
              id="PeopleDataSource"
              runat="server"
              XPath="/People/Person"
              DataFile="~/App_Data/people.xml" />

            <asp:TreeView
              id="PeopleTreeView"
              runat="server"
              DataSourceID="PeopleDataSource">
              <DataBindings>
                <asp:TreeNodeBinding DataMember="LastName"    TextField="#InnerText" />
                <asp:TreeNodeBinding DataMember="FirstName"   TextField="#InnerText" />
                <asp:TreeNodeBinding DataMember="Street"      TextField="#InnerText" />
                <asp:TreeNodeBinding DataMember="City"        TextField="#InnerText" />
                <asp:TreeNodeBinding DataMember="Region"      TextField="#InnerText" />
                <asp:TreeNodeBinding DataMember="ZipCode"     TextField="#InnerText" />
                <asp:TreeNodeBinding DataMember="Title"       TextField="#InnerText" />
                <asp:TreeNodeBinding DataMember="Description" TextField="#InnerText" />
              </DataBindings>
            </asp:TreeView>
          </td>
        </tr>
      </table>
    </form>
  </body>
</html>

See Also

Other Resources