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Filtrage de données à l'aide du contrôle XmlDataSource

  • Article

Mise à jour : novembre 2007

Vous pouvez filtrer les données XML exposées par un contrôle XmlDataSource en affectant à la propriété XPath du contrôle une expression de filtre XPath. Si vous avez spécifié une feuille de style XSL (Extensible Stylesheet Language) pour transformer les données exposées par votre contrôle XmlDataSource, l'expression de filtre XPath est appliquée une fois la transformation terminée.

L'exemple de code suivant illustre la liaison d'un contrôle XmlDataSource à un contrôle TreeView. Les données XML sont filtrées à l'aide d'une requête XPath.

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

<script >

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 xmlns="http://www.w3.org/1999/xhtml" >
  <head >
    <title>ASP.NET Example</title>
</head>
<body>
    <form id="form1" >
      <table border="0" cellpadding="3">
        <tr>
          <td valign="top">
            <b>Select Region:</b>
            <asp:DropDownList  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"
              
              XPath="/People/Person"
              DataFile="~/App_Data/people.xml" />

            <asp:TreeView
              id="PeopleTreeView"
              
              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 >

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 xmlns="http://www.w3.org/1999/xhtml" >
  <head >
    <title>ASP.NET Example</title>
</head>
<body>
    <form id="form1" >
      <table border="0" cellpadding="3">
        <tr>
          <td valign="top">
            <b>Select Region:</b>
            <asp:DropDownList  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"
              
              XPath="/People/Person"
              DataFile="~/App_Data/people.xml" />

            <asp:TreeView
              id="PeopleTreeView"
              
              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>

Voir aussi

Concepts

Vue d'ensemble du contrôle serveur Web XmlDataSource