ObjectDataSource.CacheDuration Property (System.Web.UI.WebControls)

CacheDuration Property

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Microsoft Visual Studio 2008/.NET Framework 3.5

Other versions are also available for the following:

.NET Framework Class Library

ObjectDataSource..::.CacheDuration Property

Gets or sets the length of time, in seconds, that the data source control caches data that is retrieved by the SelectMethod property.

Namespace: System.Web.UI.WebControls
Assembly: System.Web (in System.Web.dll)

Syntax

Visual Basic (Declaration)

<TypeConverterAttribute(GetType(DataSourceCacheDurationConverter))> _
Public Overridable Property CacheDuration As Integer

Visual Basic (Usage)

Dim instance As ObjectDataSource
Dim value As Integer

value = instance.CacheDuration

instance.CacheDuration = value

[TypeConverterAttribute(typeof(DataSourceCacheDurationConverter))]
public virtual int CacheDuration { get; set; }

Visual C++

[TypeConverterAttribute(typeof(DataSourceCacheDurationConverter))]
public:
virtual property int CacheDuration {
    int get ();
    void set (int value);
}

JScript

public function get CacheDuration () : int
public function set CacheDuration (value : int)

ASP.NET

<asp:ObjectDataSource CacheDuration="Int32" />

Property Value

Type: System..::.Int32
The number of seconds that the ObjectDataSource caches the results of a SelectMethod property invocation. The default is 0. The value cannot be negative.

Remarks

The ObjectDataSource control supports data caching. While data is cached, calls to the Select method retrieve data from the cache rather than from the business object that the ObjectDataSource works with. When the cache expires, the Select method retrieves data from the business object, and then caches the data again.

The ObjectDataSource control automatically caches data when the EnableCaching property is set to true and the CacheDuration property is set to a value greater than 0, which indicates the number of seconds that the cache stores data before the cache entry is discarded. A value of 0 indicates an infinitely long cache.

The cache is regulated by a combination of the duration and the CacheExpirationPolicy setting. If the CacheExpirationPolicy property is set to the Absolute value, the ObjectDataSource caches data on the first call to the Select method and holds it in memory for, at most, the amount of time that is specified by the CacheDuration property. The data might be released before the duration time, if the memory is needed. The cache is then refreshed during the next call to the Select method. If the CacheExpirationPolicy property is set to Sliding value, the data source control caches data on the first call to the Select method, but resets the time window for which it holds the cache on each subsequent call to the Select method. The cache expires if there is no activity for a time that is equal to the CacheDuration property since the last call to the Select method.

Examples

This section contains two code examples. The first code example demonstrates how an ObjectDataSource object supports caching. The second code example demonstrates how to implement a wrapper method that returns a DataSet object to enable caching with an ObjectDataSource object.

The following code example demonstrates how an ObjectDataSource control supports caching. To enable caching, you must implement the method that retrieves data, which is identified by the SelectMethod property, to return the data as a DataSet object. In this example, the EnableCaching property is set to true, and the CacheDuration and CacheExpirationPolicy properties are set. The ObjectDataSource caches data that is returned by the SelectMethod property for 30 seconds.

Visual Basic

<%@ Register TagPrefix="aspSample" Namespace="Samples.AspNet.VB" Assembly="Samples.AspNet.VB" %>
<%@ Page language="vb" %>
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN"
    "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html  >
  <head>
    <title>ObjectDataSource - VB Example</title>
  </head>
  <body>
    <form id="Form1" method="post" runat="server">

        <asp:gridview
          id="GridView1"
          runat="server"
          datasourceid="ObjectDataSource1" />

        <asp:objectdatasource
          id="ObjectDataSource1"
          runat="server"
          typename="Samples.AspNet.VB.EmployeeLogic"
          selectmethod="GetAllEmployeesAsDataSet"
          enablecaching="True"
          cacheduration="30"
          cacheexpirationpolicy="Absolute" />

    </form>
  </body>
</html>

<%@ Register TagPrefix="aspSample" Namespace="Samples.AspNet.CS" Assembly="Samples.AspNet.CS" %>
<%@ Page language="c#" %>
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN"
    "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html  >
  <head>
    <title>ObjectDataSource - C# Example</title>
  </head>
  <body>
    <form id="Form1" method="post" runat="server">

        <asp:gridview
          id="GridView1"
          runat="server"
          datasourceid="ObjectDataSource1" />

        <asp:objectdatasource
          id="ObjectDataSource1"
          runat="server"
          typename="Samples.AspNet.CS.EmployeeLogic"
          selectmethod="GetAllEmployeesAsDataSet"
          enablecaching="True"
          cacheduration="30"
          cacheexpirationpolicy="Absolute" />

    </form>
  </body>
</html>

The following code example demonstrates how to implement a wrapper method that returns a DataSet object to enable caching with an ObjectDataSource control. In the base implementation of the EmployeeLogic class, the GetAllEmployees method returns an ArrayList object. Instead of refactoring the object completely to work with the ObjectDataSource on a Web Forms page, a wrapper method named GetAllEmployeesAsDataSet is added that returns a set of NorthwindEmployee data as a DataSet.

This code example is part of a larger example provided for the ObjectDataSource class.

Visual Basic

' To support basic filtering, the employees cannot
' be returned as an array of objects, rather as a
' DataSet of the raw data values.
Public Shared Function GetAllEmployeesAsDataSet() As DataSet
   Dim employees As ICollection = GetAllEmployees()

   Dim ds As New DataSet("Table")

   ' Create the schema of the DataTable.
   Dim dt As New DataTable()
   Dim dc As DataColumn
   dc = New DataColumn("FirstName", GetType(String))
   dt.Columns.Add(dc)
   dc = New DataColumn("LastName", GetType(String))
   dt.Columns.Add(dc)
   dc = New DataColumn("Title", GetType(String))
   dt.Columns.Add(dc)
   dc = New DataColumn("Courtesy", GetType(String))
   dt.Columns.Add(dc)
   dc = New DataColumn("Supervisor", GetType(Int32))
   dt.Columns.Add(dc)

   ' Add rows to the DataTable.
   Dim emplEnum As IEnumerator = employees.GetEnumerator()
   Dim row As DataRow
   Dim ne As NorthwindEmployee
   While emplEnum.MoveNext()
      ne = CType(emplEnum.Current, NorthwindEmployee)
      row = dt.NewRow()
      row("FirstName") = ne.FirstName
      row("LastName") = ne.LastName
      row("Title") = ne.Title
      row("Courtesy") = ne.Courtesy
      row("Supervisor") = ne.Supervisor
      dt.Rows.Add(row)
   End While
   ' Add the complete DataTable to the DataSet.
   ds.Tables.Add(dt)

   Return ds
End Function 'GetAllEmployeesAsDataSet

//
// To support basic filtering, the employees cannot
// be returned as an array of objects, rather as a
// DataSet of the raw data values.
public static DataSet GetAllEmployeesAsDataSet () {
  ICollection employees = GetAllEmployees();

  DataSet ds = new DataSet("Table");

  // Create the schema of the DataTable.
  DataTable dt = new DataTable();
  DataColumn dc;
  dc = new DataColumn("FirstName", typeof(string)); dt.Columns.Add(dc);
  dc = new DataColumn("LastName",  typeof(string)); dt.Columns.Add(dc);
  dc = new DataColumn("Title",     typeof(string)); dt.Columns.Add(dc);
  dc = new DataColumn("Courtesy",  typeof(string)); dt.Columns.Add(dc);
  dc = new DataColumn("Supervisor",typeof(Int32));  dt.Columns.Add(dc);

  // Add rows to the DataTable.
  IEnumerator emplEnum = employees.GetEnumerator();
  DataRow row;
  NorthwindEmployee ne;
  while (emplEnum.MoveNext()) {
    ne = emplEnum.Current as NorthwindEmployee;
    row = dt.NewRow();
    row["FirstName"]  = ne.FirstName;
    row["LastName"]   = ne.LastName;
    row["Title"]      = ne.Title;
    row["Courtesy"]   = ne.Courtesy;
    row["Supervisor"] = ne.Supervisor;
    dt.Rows.Add(row);
  }
  // Add the complete DataTable to the DataSet.
  ds.Tables.Add(dt);

  return ds;
}

Platforms

Windows 7, Windows Vista, Windows XP SP2, Windows XP Media Center Edition, Windows XP Professional x64 Edition, Windows XP Starter Edition, Windows Server 2008 R2, Windows Server 2008, Windows Server 2003, Windows Server 2000 SP4, Windows Millennium Edition, Windows 98

The .NET Framework and .NET Compact Framework do not support all versions of every platform. For a list of the supported versions, see .NET Framework System Requirements.

Version Information

.NET Framework

Supported in: 3.5, 3.0, 2.0

Reference

ObjectDataSource Class

ObjectDataSource Members

System.Web.UI.WebControls Namespace

CacheExpirationPolicy

EnableCaching

Other Resources

ASP.NET Data Access Overview

Data Source Web Server Controls

ObjectDataSource Web Server Control Overview

Creating an ObjectDataSource Control Source Object