ASP.NET Tutorial/Cache/File Dependency

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Creating a Page Output Cache File Dependency

   <source lang="csharp">

You can create a dependency between a cached page and a file (or set of files) on your hard drive. When the file is modified, the cached page is automatically dropped and regenerated with the next page request. <%@ Page Language="C#" %> <%@ OutputCache Duration="9999" VaryByParam="none" %> <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"> <script runat="server">

   void Page_Load()
   {
       Response.AddFileDependency(MapPath("Data.xml"));
   }

</script> <html xmlns="http://www.w3.org/1999/xhtml" > <head id="Head1" runat="server">

   <title>Output Cache File Dependency</title>

</head> <body>

   <form id="form1" runat="server">
   <%= DateTime.Now.ToString("T") %>

   <asp:GridView
       id="grdProducts"
       DataSourceID="srcProducts"
       Runat="server" />
   <asp:XmlDataSource
       id="srcProducts"
       DataFile="Data.xml"
       Runat="server" />
   </form>

</body> </html></source>


Object Caching File Dependency

   <source lang="csharp">

<%@ Page Language="C#" AutoEventWireup="true" CodeFile="Default.aspx.cs" Inherits="Default_aspx" %> <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.1//EN" "http://www.w3.org/TR/xhtml11/DTD/xhtml11.dtd"> <html xmlns="http://www.w3.org/1999/xhtml" > <head runat="server">

   <title>Object Caching</title>

</head> <body>

   <form id="form1" runat="server">

Object Caching

File Dependency

    <asp:Label ID="lblMessage" runat="server" />
    

<asp:GridView ID="gv" runat="server" />
<asp:Button ID="btnClear" runat="server" Text="Clear Cache" OnClick="btnClear_Click" /> <asp:Button ID="btnPost" runat="server" Text="Post" />
   </form>

</body> </html> File: Default.aspx.cs using System; using System.Data; using System.Configuration; using System.Web; using System.Web.Security; using System.Web.UI; using System.Web.UI.WebControls; using System.Web.UI.WebControls.WebParts; using System.Web.UI.HtmlControls; using System.Web.Caching; using System.Xml; public partial class Default_aspx : System.Web.UI.Page {

   protected void Page_Load(object sender, EventArgs e)
   {
    CreateGridView();
  }
  private void CreateGridView()
  {
    DataSet dsGrid;
    dsGrid = (DataSet)Cache["GridViewDataSet"];
    if (dsGrid == null)
    {
      dsGrid = GetDataSet();
      CacheDependency fileDepends = new CacheDependency(Server.MapPath("NorthWind.xml"));
      Cache.Insert("GridViewDataSet", dsGrid, fileDepends);
      lblMessage.Text = "Data from XML file.";
    }
    else
    {
      lblMessage.Text = "Data from cache.";
    }
    gv.DataSource = dsGrid.Tables[0];
    gv.DataBind();
  }
  private DataSet GetDataSet()
  {
    DataSet dsData = new DataSet();
    XmlDataDocument doc = new XmlDataDocument();
    doc.DataSet.ReadXml(Server.MapPath("NorthWind.xml"));
    dsData = doc.DataSet;
    return dsData;
  }
 protected void btnClear_Click(object sender, EventArgs e)
  {
     Cache.Remove("GridViewDataSet");
   CreateGridView();
  }
}

File: NorthWind.xml <?xml version="1.0" encoding="UTF-16" ?> <ROOT>

 <Customers CustomerID="A" CompanyName="A" ContactName="Dan" ContactTitle="Sales" Address="Str. 57" City="Berlin" PostalCode="11111" Country="Germany" Phone="030-0074321" Fax="030-0076545" /> 
 <Customers CustomerID="B" CompanyName="B" ContactName="Ana" ContactTitle="Owner" Address="Road 22" City="New York" PostalCode="00000" Country="Mexico" Phone="(555) 555-4729" Fax="(5) 555-3745" /> 

</ROOT></source>