19.3 Collections Reference | ASP.NET in a Nutshell, Second Edition

Contents

HttpSessionState = Session.Contents

Returns a reference to the current HttpSessionState instance.

Parameter

HttpSessionState: A variable of type HttpSessionState that will receive the Contents reference.

Example

The example below calls the RemoveAll method through the Contents collection reference and then writes a message:

Sub Page_Load( )    Session.Contents.RemoveAll( )    Message.Text = "Removed all items from current Session." End Sub

Notes

This property is provided for backward compatibility with classic ASP. Properties such as the Item property and methods such as Remove and RemoveAll were accessed via the Contents property in classic ASP. In new ASP.NET development, you should access these members directly.

Keys

KeysCollection = Session.Keys

Returns a NameObjectCollectionBase.KeysCollection containing the string keys associated with all of the values stored in the Session collection.

Parameter

KeysCollection: A variable of type NameObjectCollectionBase.KeysCollection that will receive the Keys property value.

Example

The example loops through the collection of keys in the Session collection and then displays the key name and the value associated with it by using the Text property of the Message label control:

Sub Page_Load( )    Dim Key As String    Message.Text = "Session Keys:"    For Each Key in Session.Keys       Message.Text &= "<br/>Key:&nbsp;&nbsp;&nbsp;" & Key       Message.Text &= "<br/>Value:&nbsp;&nbsp;&nbsp;" & _                       CStr(Session(Key))    Next End Sub

Notes

The Keys property provides one of many ways to iterate over the contents of the Session collection.

StaticObjects

HttpStaticObjectsCollection = Session.StaticObjects

Returns an HttpStaticObjectsCollection containing all objects instantiated in global.asax by using the <object runat="server"> syntax whose scope is set to Session.

Parameter

HttpStaticObjectsCollection: A variable of type HttpStaticObjectsCollection that will receive the StaticObjects property value.

Example

The example uses the Count property of the HttpStaticObjectsCollection class to display the number of objects in the current application declared with the <object scope="session" runat="server"/> syntax in global.asax. It then checks the type of each object and, if it is a TextBox web control, adds it to the Controls collection of the form:

Sub Page_Load( )    Message.Text = "There are " & Session.StaticObjects.Count & _       " objects declared with the " & _       "&lt;object runat=&quot;server&quot;&gt; syntax in Session scope."    Dim myobj As Object    For Each myObj in Session.StaticObjects       If myObj.Value.GetType.ToString( ) = _          "System.Web.UI.WebControls.TextBox" Then          myForm.Controls.Add(myObj.Value)       End If    Next End Sub

You also need to modify the <body> section of the document as follows:

<body>    <form  runat="server">       <asp:label  runat="server"/>    </form> </body>

Notes

This property is provided for backward compatibility with classic ASP. You should think carefully before instantiating objects with Session or Application scope because of the impact such objects have on resource usage and application scalability. In most cases, it is advisable to limit objects to page scope.

Each object in the collection is represented by the DictionaryEntry structure, so its key and value are not directly accessible. To access the key and/or value, use the Key and/or Value members of the DictionaryEntry structure, as shown in the example.