ObjectDataSource.SqlCacheDependency 属性
定义
重要
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获取或设置一个用分号分隔的字符串，指示用于 Microsoft SQL Server 缓存依赖项的数据库和表。
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, setPublic Overridable Property SqlCacheDependency As String属性值
一个字符串，指示用于 SQL Server 缓存依赖项的数据库和表。
示例
本部分包含两个代码示例。 第一个代码示例演示如何创建SQL Server缓存依赖项并设置SqlCacheDependency对象的属性ObjectDataSource。 第二个代码示例演示如何实现返回对象 DataSet 以启用对象缓存和筛选的 ObjectDataSource 包装方法。
下面的代码示例演示如何创建SQL Server缓存依赖项并设置SqlCacheDependency控件的属性ObjectDataSource。 在此示例中，每 120 秒轮询一次数据库。 如果 Northwind Traders Employees 表中的数据在该时间发生更改，则控件缓存 ObjectDataSource 并由控件显示 GridView 的任何数据都已过期，并在页面的下一个请求中检索一组新数据。
<%@ 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>
下面的代码示例演示如何实现返回对象 DataSet 以使用控件启用缓存和筛选 ObjectDataSource 的包装方法。 在类的 EmployeeLogic 基实现中，该方法 GetAllEmployees 返回一个 ArrayList 对象。 添加名为GetAllEmployeesAsDataSet的包装方法，而不是完全重构对象以ObjectDataSource在Web Forms页上使用。该方法将返回一组NorthwindEmployee数据作为一个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
注解
该控件支持一个可选的过期策略，该 ObjectDataSource 策略基于 SqlCacheDependency 数据缓存的对象， (必须为数据库服务器配置服务) 。
SQL Server支持两种缓存无效机制：轮询和通知。 每个机制都有 SqlCacheDependency 一个不同的对象语法。
仅 ObjectDataSource 支持轮询。 该SqlCacheDependency字符串用于创建在SqlDependency执行方法之前Select传递给DbCommand构造函数的对象。 该SqlCacheDependency字符串根据指令使用的@ Page相同格式标识数据库和表，其中字符串的第一部分是SQL Server数据库的连接字符串，后跟冒号分隔符，最后是数据库表的名称 (例如 "connectionstring1:table1") 。 SqlCacheDependency如果属性依赖于多个表，则连接字符串和表名对由分号分隔 (，例如 "connectionstring1:table1";connectionstring2:table2" ，) 。
若要支持通知，必须在属性的 SelectMethod 实现中编写缓存逻辑，并在代码中处理对象的构造 SqlCacheDependency 。