Retrieving Values of Cached Items

ASP.NET Web Applications ASP .NET Caching Features Caching Application Data

Retrieving data from the Cache is simple; you need only to specify the key that represents the data. You then write code to display the data on your page.

The following code retrieves data that is assigned a key of myDataSet and assigns its value to a local variable named myData, verifies that the data still exists in the cache, and then displays the data in a DataGrid control.

DataView myData;
myData = ( DataView ) Cache [ "myDataSet" ];

if ( myData != null )
   myGrid.DataSource = myData;
   myGrid.DataBind ( );
}

Dim myData As DataView
myData = CType ( Cache ( "myDataSet" ), DataView )

If Not ( myData Is Nothing ) Then
   myGrid.DataSource = myData
   myGrid.DataBind ( )
End If

A more complex situation is how your application responds when the data is not in the cache. The following example modifies the code in the previous procedure to check for the cached data, and if it is not in the cache, the example recreates it and adds it to the cache.

DataView myData = ( DataView ) Cache [ "myDataSet" ];
if ( myData == null )
   SqlConnection myConn = new SqlConnection ( 
      "server=localhost;uid=sa;pwd=;database=pubs" );
   SqlDataAdapter myCommand = new SqlDataAdapter ( "select * from Authors", myConn );

   DataSet ds = new DataSet ( );
   myCommand.Fill ( ds, "Authors" );

   myData = new DataView ( ds.Tables [ "Authors" ] );
   Cache [ "myDataSet" ] = myData;
}
myGrid.DataSource=myData;
myGrid.DataBind ( );

Dim myData As DataView = CType ( Cache ( "myDataSet" ), DataView )
If myData Is Nothing Then
   Dim myConn As New SqlConnection ( _
      "server=localhost;uid=sa;pwd=;database=pubs" )
   Dim myCommand As New SqlDataAdapter ( "select * from Authors", myConn )

   Dim ds As New DataSet ( )
   myCommand.Fill ( ds, "Authors" )

   myData = New DataView ( ds.Tables ( "Authors" ) )
   Cache ( "myDataSet" ) = myData
End If
myGrid.DataSource = myData
myGrid.DataBind ( )

Adding Items to the Cache Deleting Items from the Cache Notifying Applications When an Item is Deleted from the Cache

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Retrieving Values of Cached Items

To retrieve the value of a cached item

To check for the existence of an item in the cache

See Also