13.3 Collections Reference

AllKeys

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Dim StateVars(Application.Count) As String StateVars = Application.AllKeys

Returns a string array of key names stored in the HttpApplicationState object.

Parameter

StateVars

A variable of type String array that will receive the array of key names.

Example

The example displays all keys of data stored to the Application object:

Sub Page_Load( )    Dim I as Integer    Dim StateVars(Application.Count - 1) As String    StateVars = Application.AllKeys    For I = 0 to StateVars.Length - 1        Message.Text = Message.Text + StateVars(I) + "<br/>"    Next I End Sub

Notes

This property provides a list of key names assigned to all current Application variables.

Contents

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HttpApplicationState = Application.Contents

Returns a reference to the current HttpApplicationState instance.

Parameter

HttpApplicationState

A variable of type HttpApplicaitonState 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( ) Application.Contents.RemoveAll( ) Message.Text = "Removed all items from current Application." 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. For example, instead of calling the RemoveAll method through the Contents property, you can call RemoveAll method directly:

Application.RemoveAll( )

Keys

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KeysCollection = Application.Keys

Returns a NameObjectCollectionBase.KeysCollection containing the string keys associated with all values stored in the Application 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 Application collection, and then displays the key name and the value associated with it by using the Text property of the Message control:

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

Notes

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

StaticObjects

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HttpStaticObjectsCollection = Application.StaticObjects

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

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="Application" runat="server"/> syntax in global.asax. It then checks the type of each object, and if it is a Web TextBox control, adds it to the Controls collection of the current page.

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

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.

Note that 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.