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ObjectDataSource.SqlCacheDependency Property

Note: This property is new in the .NET Framework version 2.0.

Gets or sets a semicolon-delimited string that indicates which databases and tables to use for the Microsoft SQL Server cache dependency.

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

public virtual string SqlCacheDependency { get; set; }
/** @property */
public String get_SqlCacheDependency ()

/** @property */
public void set_SqlCacheDependency (String value)

public function get SqlCacheDependency () : String

public function set SqlCacheDependency (value : String)

Property Value

A string that indicates which databases and tables to use for the SQL Server cache dependency.

The ObjectDataSource control supports an optional expiration policy that is based on the SqlCacheDependency object for the data cache (the service must be configured for the database server).

SQL Server supports two mechanisms for cache invalidation—polling and notification. Each has a different syntax for the SqlCacheDependency object.

The ObjectDataSource supports only polling. The SqlCacheDependency string is used to create a SqlDependency object that is passed to the DbCommand constructor before the Select method is executed. The SqlCacheDependency string identifies databases and tables according to the same format that is used by the @ Page directive, where the first part of the string is a connection string to a SQL Server database, followed by a colon delimiter, and finally the name of the database table (for example, "connectionstring1:table1"). If the SqlCacheDependency property depends on more than one table, the connection string-and-table name pairs are separated by semi-colons (for example, "connectionstring1:table1";connectionstring2:table2").

To support notification, you must write the cache logic in the implementation of your SelectMethod method and handle the construction of the SqlCacheDependency object in your code.

This section contains two code examples. The first code example demonstrates how to create a SQL Server cache dependency and set the SqlCacheDependency property of a ObjectDataSource object. The second code example demonstrates how to implement a wrapper method that returns a DataSet object to enable caching and filtering with an ObjectDataSource object.

The following code example demonstrates how to create a SQL Server cache dependency and set the SqlCacheDependency property of a ObjectDataSource control. In this example, the database is polled every 120 seconds. If the data in the Northwind Traders Employees table changes during that time, any data that is cached by the ObjectDataSource control and displayed by the GridView control is expired and a new set of data is retrieved on the next request for the page.

<%@ Register TagPrefix="aspSample" Namespace="Samples.AspNet.CS" Assembly="Samples.AspNet.CS" %>
<%@ Page language="c#" %>

<!--
The page uses an example configuration that includes
connection strings and a defined SqlCacheDependecy.

<?xml version="1.0"?>
<configuration>

  <connectionStrings>
    <add name="MyNorthwind"
         connectionString="Data Source=localhost;Integrated Security=SSPI;Initial Catalog=Northwind"
         providerName="System.Data.SqlClient" />
  </connectionStrings>

  <system.web>
    <cache>
      <sqlCacheDependency enabled="true">
        <databases>
          <add
            name="Northwind"
            connectionStringName="MyNorthwind"
            pollTime="120000" />
        </databases>
      </sqlCacheDependency>
    </cache>

  </system.web>
</configuration>
-->



<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="300"
          cacheexpirationpolicy="Absolute"
          sqlcachedependency="Northwind:Employees" />

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

<%@ Register TagPrefix="aspSample" Namespace="Samples.AspNet.JSL" Assembly="Samples.AspNet.JSL" %>
<%@ Page language="VJ#" %>

<!--

The page uses an example configuration that includes
connection strings and a defined SqlCacheDependecy.

<?xml version="1.0"?>
<configuration>

  <connectionStrings>
    <add name = "NorthwindConnection" connectionString = "Data Source=localhost;Integrated Security=SSPI;Initial Catalog=Northwind" />
  </connectionStrings>

  <system.web>

    ...

    <cache>
      <sqlCacheDependency enabled="true">
        <databases>
          <add
            name="Northwind_Remote"
            connectionStringName="NorthwindConnection"
            pollTime="120000" />
        </databases>
      </sqlCacheDependency>
    </cache>

  </system.web>
</configuration>
-->



<html>
  <head>
    <title>ObjectDataSource - VJ# 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.JSL.EmployeeLogic"
          selectmethod="GetAllEmployeesAsDataSet"
          enablecaching="True"
          cacheduration="300"
          cacheexpirationpolicy="Absolute"
          sqlcachedependency="Northwind_Remote:Employees" />

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

The following code example demonstrates how to implement a wrapper method that returns a DataSet object to enable caching and filtering 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.

namespace Samples.AspNet.CS {

using System;
using System.Collections;
using System.Configuration;
using System.Data;
using System.Data.SqlClient;
using System.Web.UI;
using System.Web.UI.WebControls;
  //
  // EmployeeLogic is a stateless business object that encapsulates
  // the operations one can perform on a NorthwindEmployee object.
  //
  public class EmployeeLogic {

    // Returns a collection of NorthwindEmployee objects.
    public static ICollection GetAllEmployees () {
      ArrayList al = new ArrayList();

      ConnectionStringSettings cts = ConfigurationManager.ConnectionStrings["NorthwindConnection"];

      SqlDataSource sds
        = new SqlDataSource(cts.ConnectionString,
                            "SELECT EmployeeID FROM Employees");
      try {
        IEnumerable IDs = sds.Select(DataSourceSelectArguments.Empty);

        // Iterate through the Enumeration and create a
        // NorthwindEmployee object for each ID.
        IEnumerator enumerator = IDs.GetEnumerator();
        while (enumerator.MoveNext()) {
          // The IEnumerable contains DataRowView objects.
          DataRowView row = enumerator.Current as DataRowView;
          string id = row["EmployeeID"].ToString();
          NorthwindEmployee nwe = new NorthwindEmployee(id);
          // Add the NorthwindEmployee object to the collection.
          al.Add(nwe);
        }
      }
      finally {
        // If anything strange happens, clean up.
        sds.Dispose();
      }

      return al;
    }

    //
    // 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;
    }
    public static NorthwindEmployee GetEmployee(object anID) {
      if (anID.Equals("-1") ||
          anID.Equals(DBNull.Value) ) {
        return new NorthwindEmployee();
      }
      else {
        return new NorthwindEmployee(anID);
      }
    }

    public static void UpdateEmployeeInfo(NorthwindEmployee ne) {
      bool retval = ne.Save();
      if (! retval) { throw new NorthwindDataException("UpdateEmployee failed."); }
    }

    public static void DeleteEmployee(NorthwindEmployee ne) {
      bool retval = ne.Delete();
      if (! retval) { throw new NorthwindDataException("DeleteEmployee failed."); }
    }
  }

  public class NorthwindEmployee {

    public NorthwindEmployee () {
      ID = DBNull.Value;
      lastName = "";
      firstName = "";
      title="";
      titleOfCourtesy = "";
      reportsTo = -1;
    }

    public NorthwindEmployee (object anID) {
      this.ID = anID;

      SqlConnection conn
        = new SqlConnection (ConfigurationManager.ConnectionStrings["NorthwindConnection"].ConnectionString);
      SqlCommand sc =
        new SqlCommand(" SELECT FirstName,LastName,Title,TitleOfCourtesy,ReportsTo " +
                       " FROM Employees " +
                       " WHERE EmployeeID = @empId",
                       conn);
      // Add the employee ID parameter and set its value.
      sc.Parameters.Add(new SqlParameter("@empId",SqlDbType.Int)).Value = Int32.Parse(anID.ToString());
      SqlDataReader sdr = null;

      try {
        conn.Open();
        sdr = sc.ExecuteReader();

        // Only loop once.
        if (sdr != null && sdr.Read()) {
          // The IEnumerable contains DataRowView objects.
          this.firstName        = sdr["FirstName"].ToString();
          this.lastName         = sdr["LastName"].ToString();
          this.title            = sdr["Title"].ToString();
          this.titleOfCourtesy  = sdr["TitleOfCourtesy"].ToString();
          if (! sdr.IsDBNull(4)) {
            this.reportsTo        = sdr.GetInt32(4);
          }
        }
        else {
          throw new NorthwindDataException("Data not loaded for employee id.");
        }
      }
      finally {
        try {
          if (sdr != null) sdr.Close();
          conn.Close();
        }
        catch (SqlException) {
          // Log an event in the Application Event Log.
          throw;
        }
      }
    }

    private object ID;
    public string EmpID {
      get { return ID.ToString();  }
    }

    private string lastName;
    public string LastName {
      get { return lastName; }
      set { lastName = value; }
    }

    private string firstName;
    public string FirstName {
      get { return firstName; }
      set { firstName = value;  }
    }

    public string FullName {
      get { return FirstName + " " + LastName; }
    }

    private string title;
    public String Title {
      get { return title; }
      set { title = value; }
    }

    private string titleOfCourtesy;
    public string Courtesy {
      get { return titleOfCourtesy; }
      set { titleOfCourtesy = value; }
    }

    private int    reportsTo;
    public int Supervisor {
      get { return reportsTo; }
      set { reportsTo = value; }
    }

    public bool Save () {
      // Implement persistence logic.
      return true;
    }

    public bool Delete () {
      // Implement delete logic.
      return true;
    }
  }

  internal class NorthwindDataException: Exception {
    public NorthwindDataException(string msg) : base (msg) { }
  }
}

package Samples.AspNet.JSL;

import System.*;
import System.Collections.*;
import System.Configuration.*;
import System.Data.*;
import System.Data.SqlClient.*;
import System.Web.UI.*;
import System.Web.UI.WebControls.*;

//
// EmployeeLogic is a stateless business object that encapsulates
// the operations one can perform on a NorthwindEmployee object.
//
public class EmployeeLogic
{
    // Returns a collection of NorthwindEmployee objects.
    public static ICollection GetAllEmployees() throws NorthwindDataException
    {
        ArrayList al = new ArrayList();

		ConnectionStringSettings cts =
			ConfigurationManager.get_ConnectionStrings().get_Item("NorthwindConnection");

        SqlDataSource sds = new SqlDataSource(cts.get_ConnectionString(),
            "SELECT EmployeeID FROM Employees");
        try {
            IEnumerable ids = sds.Select(DataSourceSelectArguments.get_Empty());
            // Iterate through the Enumeration and create a
            // NorthwindEmployee object for each ID.
            IEnumerator enumerator = ids.GetEnumerator();
            while (enumerator.MoveNext()) {
                // The IEnumerable contains DataRowView objects.
                DataRowView row = (DataRowView)enumerator.get_Current();
                String idObj = row.get_Item("EmployeeID").ToString();
                NorthwindEmployee nwe = new NorthwindEmployee(idObj);
                // Add the NorthwindEmployee object to the collection.
                al.Add(nwe);
            }
        }
        finally {
            // If anything strange happens, clean up.
            sds.Dispose();
        }
        return al;
    } //GetAllEmployees

    //
    // 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() throws NorthwindDataException
    {
        ICollection employees = GetAllEmployees();

        DataSet ds = new DataSet("Table");
        // Create the schema of the DataTable.
        DataTable dt = new DataTable();
        DataColumn dc;
        dc = new DataColumn("FirstName", String.class.ToType());
        dt.get_Columns().Add(dc);
        dc = new DataColumn("LastName", String.class.ToType());
        dt.get_Columns().Add(dc);
        dc = new DataColumn("Title", String.class.ToType());
        dt.get_Columns().Add(dc);
        dc = new DataColumn("Courtesy", String.class.ToType());
        dt.get_Columns().Add(dc);
        dc = new DataColumn("Supervisor", Int32.class.ToType());
        dt.get_Columns().Add(dc);
        // Add rows to the DataTable.
        IEnumerator emplEnum = employees.GetEnumerator();
        DataRow row;
        NorthwindEmployee ne;
        while (emplEnum.MoveNext()) {
            ne = (NorthwindEmployee)emplEnum.get_Current();
            row = dt.NewRow();
            row.set_Item("FirstName", ne.get_FirstName());
            row.set_Item("LastName", ne.get_LastName());
            row.set_Item("Title", ne.get_Title());
            row.set_Item("Courtesy", ne.get_Courtesy());
            row.set_Item("Supervisor", (Int32)ne.get_Supervisor());
            dt.get_Rows().Add(row);
        }
        // Add the complete DataTable to the DataSet.
        ds.get_Tables().Add(dt);

        return ds;
    } //GetAllEmployeesAsDataSet

    public static NorthwindEmployee GetEmployee(Object anID)
        throws NorthwindDataException
    {
        if (anID.Equals("-1") || anID.Equals(DBNull.Value)) {
            return new NorthwindEmployee();
        }
        else {
            return new NorthwindEmployee(anID);
        }
    } //GetEmployee

    public static void UpdateEmployeeInfo(NorthwindEmployee ne)
        throws NorthwindDataException
    {
        boolean retVal = ne.Save();
        if (!(retVal)) {
            throw new NorthwindDataException("UpdateEmployee failed.");
        }
    } //UpdateEmployeeInfo

    public static void DeleteEmployee(NorthwindEmployee ne)
        throws NorthwindDataException
    {
        boolean retVal = ne.Delete();
        if (!(retVal)) {
            throw new NorthwindDataException("DeleteEmployee failed.");
        }
    } //DeleteEmployee
} //EmployeeLogic

public class NorthwindEmployee
{
    public NorthwindEmployee()
    {
        id = DBNull.Value;
        lastName = "";
        firstName = "";
        title = "";
        titleOfCourtesy = "";
        reportsTo = -1;
    } //NorthwindEmployee

    public NorthwindEmployee(Object anID) throws NorthwindDataException
    {
        this.id = anID;

		SqlConnection conn = new SqlConnection(ConfigurationManager.
			get_ConnectionStrings().get_Item("NorthwindConnection").
			get_ConnectionString());
        SqlCommand sc = new SqlCommand(" SELECT FirstName,LastName,Title,"
            + "TitleOfCourtesy,ReportsTo " + " FROM Employees "
            + " WHERE EmployeeID = @empId", conn);
        // Add the employee ID parameter and set its value.
        sc.get_Parameters().Add(new SqlParameter("@empId", SqlDbType.Int)).
            set_Value(anID.ToString());
        SqlDataReader sdr = null;

        try {
            conn.Open();
            sdr = sc.ExecuteReader();
            // Only loop once.
            if (sdr != null && sdr.Read()) {
                // The IEnumerable contains DataRowView objects.
                this.firstName = sdr.get_Item("FirstName").ToString();
                this.lastName = sdr.get_Item("LastName").ToString();
                this.title = sdr.get_Item("Title").ToString();
                this.titleOfCourtesy = sdr.get_Item("TitleOfCourtesy").ToString();
                if (!(sdr.IsDBNull(4))) {
                    this.reportsTo = sdr.GetInt32(4);
                }
            }
            else {
                throw new NorthwindDataException("Data not loaded for"
                    + " employee id.");
            }
        }
        finally {
            try {
                if (sdr != null) {
                    sdr.Close();
                }
                conn.Close();
            }
            catch (SqlException exp) {
                // Log an event in the Application Event Log.
            }
        }
    } //NorthwindEmployee

    private Object id;

    /** @property 
     */
    public String get_EmpID()
    {
        return id.ToString();
    } //get_EmpID

    private String lastName;

    /** @property 
     */
    public String get_LastName()
    {
        return lastName;
    } //get_LastName

    /** @property 
     */
    public void set_LastName(String value)
    {
        lastName = value;
    } //set_LastName

    private String firstName;

    /** @property 
     */
    public String get_FirstName()
    {
        return firstName;
    } //get_FirstName

    /** @property 
     */
    public void set_FirstName(String value)
    {
        firstName = value;
    } //set_FirstName

    /** @property 
     */
    public String get_FullName()
    {
        return get_FirstName() + " " + get_LastName();
    } //get_FullName

    private String title;

    /** @property 
     */
    public String get_Title()
    {
        return title;
    } //get_Title

    /** @property 
     */
    public void set_Title(String value)
    {
        title = value;
    } //set_Title

    private String titleOfCourtesy;

    /** @property 
     */
    public String get_Courtesy()
    {
        return titleOfCourtesy;
    } //get_Courtesy

    /** @property 
     */
    public void set_Courtesy(String value)
    {
        titleOfCourtesy = value;
    } //set_Courtesy

    private int reportsTo;

    /** @property 
     */
    public int get_Supervisor()
    {
        return reportsTo;
    } //get_Supervisor

    /** @property 
     */
    public void set_Supervisor(int value)
    {
        reportsTo = value;
    } //set_Supervisor

    public boolean Save()
    {
        // Implement persistence logic.
        return true;
    } //Save

    public boolean Delete()
    {
        // Implement delete logic.
        return true;
    } //Delete
} //NorthwindEmployee

class NorthwindDataException extends Exception
{
    public NorthwindDataException(String msg)
    {
        super(msg);
    } //NorthwindDataException
} //NorthwindDataException

Windows 98, Windows 2000 SP4, Windows Server 2003, Windows XP Media Center Edition, Windows XP Professional x64 Edition, Windows XP SP2, Windows XP Starter Edition

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

.NET Framework

Supported in: 2.0
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