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ObjectDataSource.SqlCacheDependency Propiedad

Definición

Obtiene o establece una cadena delimitada por puntos y comas que indica las bases de datos y las tablas que deben utilizarse para la dependencia de caché de Microsoft SQL Server.

public:
 virtual property System::String ^ SqlCacheDependency { System::String ^ get(); void set(System::String ^ value); };
public virtual string SqlCacheDependency { get; set; }
member this.SqlCacheDependency : string with get, set
Public Overridable Property SqlCacheDependency As String

Valor de propiedad

Cadena que indica las bases de datos y las tablas que deben utilizarse para la dependencia de caché de SQL Server.

Ejemplos

Esta sección contiene dos ejemplos de código. En el primer ejemplo de código se muestra cómo crear una dependencia de caché de SQL Server y establecer la SqlCacheDependency propiedad de un ObjectDataSource objeto . En el segundo ejemplo de código se muestra cómo implementar un método contenedor que devuelve un DataSet objeto para habilitar el almacenamiento en caché y el filtrado con un ObjectDataSource objeto .

En el ejemplo de código siguiente se muestra cómo crear una dependencia de caché de SQL Server y establecer la SqlCacheDependency propiedad de un ObjectDataSource control . En este ejemplo, la base de datos se sondea cada 120 segundos. Si los datos de la tabla Empleados de Northwind Traders cambian durante ese tiempo, los datos almacenados en caché por el ObjectDataSource control y mostrados por el GridView control expiran y se recupera un nuevo conjunto de datos en la siguiente solicitud de la página.

<%@ 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>
-->



<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN"
    "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml" >
  <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.VB" Assembly="Samples.AspNet.VB" %>
<%@ Page language="vb" %>

<!--

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>
-->



<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN"
    "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml" >
  <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="300"
          cacheexpirationpolicy="Absolute"
          sqlcachedependency="Northwind:Employees" />

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

En el ejemplo de código siguiente se muestra cómo implementar un método contenedor que devuelve un DataSet objeto para habilitar el almacenamiento en caché y el filtrado con un ObjectDataSource control . En la implementación base de la EmployeeLogic clase , el GetAllEmployees método devuelve un ArrayList objeto . En lugar de refactorizar completamente el objeto para trabajar con ObjectDataSource en una página de Formularios Web Forms, se agrega un método contenedor denominado GetAllEmployeesAsDataSet que devuelve un conjunto de NorthwindEmployee datos como .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) { }
  }
}
Imports System.Collections
Imports System.Configuration
Imports System.Data
Imports System.Data.SqlClient
Imports System.Web.UI
Imports System.Web.UI.WebControls

Namespace Samples.AspNet.VB

' 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 Shared Function GetAllEmployees() As ICollection
      Dim al As New ArrayList()

      Dim cts As ConnectionStringSettings = ConfigurationManager.ConnectionStrings("NorthwindConnection")

      Dim sds As New SqlDataSource(cts.ConnectionString, "SELECT EmployeeID FROM Employees")

      Try
         Dim IDs As IEnumerable = sds.Select(DataSourceSelectArguments.Empty)

         ' Iterate through the Enumeration and create a
         ' NorthwindEmployee object for each ID.
         Dim enumerator As IEnumerator = IDs.GetEnumerator()
         While enumerator.MoveNext()
            ' The IEnumerable contains DataRowView objects.
            Dim row As DataRowView = CType(enumerator.Current,DataRowView)
            Dim id As String = row("EmployeeID").ToString()
            Dim nwe As New NorthwindEmployee(id)
            ' Add the NorthwindEmployee object to the collection.
            al.Add(nwe)
         End While
      Finally
         ' If anything strange happens, clean up.
         sds.Dispose()
      End Try

      Return al
   End Function '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 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

   Public Shared Function GetEmployee(anID As Object) As NorthwindEmployee
      If anID.Equals("-1") OrElse anID.Equals(DBNull.Value) Then
         Return New NorthwindEmployee()
      Else
         Return New NorthwindEmployee(anID)
      End If
   End Function 'GetEmployee


   Public Shared Sub UpdateEmployeeInfo(ne As NorthwindEmployee)
      Dim retval As Boolean = ne.Save()
      If Not retval Then
         Throw New NorthwindDataException("UpdateEmployee failed.")
      End If
   End Sub

   Public Shared Sub DeleteEmployee(ne As NorthwindEmployee)
      Dim retval As Boolean = ne.Delete()
      If Not retval Then
         Throw New NorthwindDataException("DeleteEmployee failed.")
      End If
   End Sub
End Class


Public Class NorthwindEmployee


   Public Sub New()
      ID = DBNull.Value
      aLastName = ""
      aFirstName = ""
      aTitle = ""
      titleOfCourtesy = ""
      reportsTo = - 1
   End Sub


   Public Sub New(anID As Object)
      Me.ID = anID

      Dim cts As ConnectionStringSettings = ConfigurationManager.ConnectionStrings("NorthwindConnection")

      Dim conn As New SqlConnection(cts.ConnectionString)

      Dim sc As 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())
      Dim sdr As SqlDataReader = Nothing

      Try
         conn.Open()
         sdr = sc.ExecuteReader()

         ' Only loop once.
         If Not (sdr Is Nothing) AndAlso sdr.Read() Then
            ' The IEnumerable contains DataRowView objects.
            Me.aFirstName = sdr("FirstName").ToString()
            Me.aLastName = sdr("LastName").ToString()
            Me.aTitle = sdr("Title").ToString()
            Me.titleOfCourtesy = sdr("TitleOfCourtesy").ToString()
            If Not sdr.IsDBNull(4) Then
               Me.reportsTo = sdr.GetInt32(4)
            End If
         Else
            Throw New NorthwindDataException("Data not loaded for employee id.")
         End If
      Finally
         Try
            If Not (sdr Is Nothing) Then
               sdr.Close()
            End If
            conn.Close()
         Catch se As SqlException
            ' Log an event in the Application Event Log.
            Throw
         End Try
      End Try
   End Sub

   Private ID As Object
   Public ReadOnly Property EmpID() As String
      Get
         Return ID.ToString()
      End Get
   End Property

   Private aLastName As String
   Public Property LastName() As String
      Get
         Return aLastName
      End Get
      Set
         aLastName = value
      End Set
   End Property

   Private aFirstName As String
   Public Property FirstName() As String
      Get
         Return aFirstName
      End Get
      Set
         aFirstName = value
      End Set
   End Property

   Public ReadOnly Property FullName() As String
      Get
         Return FirstName & " " & LastName
      End Get
   End Property

   Private aTitle As String
   Public Property Title() As String
      Get
         Return aTitle
      End Get
      Set
         aTitle = value
      End Set
   End Property

   Private titleOfCourtesy As String
   Public Property Courtesy() As String
      Get
         Return titleOfCourtesy
      End Get
      Set
         titleOfCourtesy = value
      End Set
   End Property

   Private reportsTo As Integer
   Public Property Supervisor() As Integer
      Get
         Return reportsTo
      End Get
      Set
         reportsTo = value
      End Set
   End Property

   Public Function Save() As Boolean

      ' Implement persistence logic.
      Return True

   End Function 'Save


   Public Function Delete() As Boolean

      ' Implement delete logic.
      Return True

   End Function 'Delete
End Class


Friend Class NorthwindDataException
   Inherits Exception

   Public Sub New(msg As String)
      MyBase.New(msg)
   End Sub
End Class
End Namespace

Comentarios

El ObjectDataSource control admite una directiva de expiración opcional basada en el SqlCacheDependency objeto de la caché de datos (el servicio debe configurarse para el servidor de bases de datos).

SQL Server admite dos mecanismos para la invalidación de caché: sondeo y notificación. Cada mecanismo tiene una sintaxis diferente para el SqlCacheDependency objeto .

solo ObjectDataSource admite sondeos. La SqlCacheDependency cadena se usa para crear un SqlDependency objeto que se pasa al DbCommand constructor antes de ejecutar el Select método. La SqlCacheDependency cadena identifica las bases de datos y las tablas según el mismo formato que usa la @ Page directiva , donde la primera parte de la cadena es una cadena de conexión a una base de datos de SQL Server, seguida de un delimitador de dos puntos y, por último, el nombre de la tabla de base de datos (por ejemplo, "connectionstring1:table1"). Si la SqlCacheDependency propiedad depende de más de una tabla, los pares de cadena de conexión y nombre de tabla se separan por punto y coma (por ejemplo, "connectionstring1:table1";connectionstring2:table2").

Para admitir la notificación, debe escribir la lógica de caché en la implementación de SelectMethod la propiedad y controlar la construcción del objeto en el SqlCacheDependency código.

Se aplica a

Consulte también