Substitution Class
 

Specifies a section on an output-cached Web page that is exempt from caching. At this location, dynamic content is retrieved and substituted for the Substitution control.

Namespace:   System.Web.UI.WebControls
Assembly:  System.Web (in System.Web.dll)

SystemObject
   System.Web.UIControl
    System.Web.UI.WebControlsSubstitution

public class Substitution : Control
public ref class Substitution : Control
type Substitution = 
    class
        inherit Control
    end
Public Class Substitution
	Inherits Control
NameDescription
System_CAPS_pubmethod Substitution

Initializes a new instance of the Substitution class.

NameDescription
System_CAPS_protproperty

Gets the browser-specific adapter for the control.(Inherited from Control.)

System_CAPS_pubproperty

Gets or sets the application-relative virtual directory of the Page or UserControl object that contains this control.(Inherited from Control.)

System_CAPS_pubproperty

This API supports the product infrastructure and is not intended to be used directly from your code. Gets the control that contains this control's data binding.(Inherited from Control.)

System_CAPS_protproperty

Gets a value that indicates whether the server control's child controls have been created.(Inherited from Control.)

System_CAPS_pubproperty

Gets the control ID for HTML markup that is generated by ASP.NET.(Inherited from Control.)

System_CAPS_pubproperty

Gets or sets the algorithm that is used to generate the value of the property.(Inherited from Control.)

System_CAPS_protproperty

Gets a character value representing the separator character used in the property.(Inherited from Control.)

System_CAPS_protproperty

Gets the HttpContext object associated with the server control for the current Web request.(Inherited from Control.)

System_CAPS_pubproperty

Gets a ControlCollection object that represents the child controls for a specified server control in the UI hierarchy.(Inherited from Control.)

System_CAPS_pubproperty

Gets a reference to the naming container if the naming container implements IDataItemContainer.(Inherited from Control.)

System_CAPS_pubproperty

Gets a reference to the naming container if the naming container implements IDataKeysControl.(Inherited from Control.)

System_CAPS_protproperty

Gets a value indicating whether a control is being used on a design surface.(Inherited from Control.)

System_CAPS_pubproperty

Gets or sets a value indicating whether themes apply to this control.(Inherited from Control.)

System_CAPS_pubproperty

Gets or sets a value indicating whether the server control persists its view state, and the view state of any child controls it contains, to the requesting client.(Inherited from Control.)

System_CAPS_protproperty

Gets a list of event handler delegates for the control. This property is read-only.(Inherited from Control.)

System_CAPS_protproperty

Gets a value indicating whether the current server control's child controls have any saved view-state settings.(Inherited from Control.)

System_CAPS_pubproperty

Gets or sets the programmatic identifier assigned to the server control.(Inherited from Control.)

System_CAPS_protproperty

This API supports the product infrastructure and is not intended to be used directly from your code. Gets the character used to separate control identifiers.(Inherited from Control.)

System_CAPS_protproperty

Gets a value indicating whether controls contained within this control have control state.(Inherited from Control.)

System_CAPS_protproperty

Gets a value that indicates whether the server control is saving changes to its view state.(Inherited from Control.)

System_CAPS_protproperty

Gets a value indicating whether view state is enabled for this control.(Inherited from Control.)

System_CAPS_protproperty

Gets a value indicating whether the control participates in loading its view state by instead of index. (Inherited from Control.)

System_CAPS_pubproperty

Gets or sets the name of the callback method to invoke when the Substitution control executes.

System_CAPS_pubproperty

Gets a reference to the server control's naming container, which creates a unique namespace for differentiating between server controls with the same property value.(Inherited from Control.)

System_CAPS_pubproperty

Gets a reference to the Page instance that contains the server control.(Inherited from Control.)

System_CAPS_pubproperty

Gets a reference to the server control's parent control in the page control hierarchy.(Inherited from Control.)

System_CAPS_pubproperty

Gets a value that specifies the ASP.NET version that rendered HTML will be compatible with.(Inherited from Control.)

System_CAPS_pubproperty

Gets information about the container that hosts the current control when rendered on a design surface.(Inherited from Control.)

System_CAPS_pubproperty

Gets or sets the skin to apply to the control.(Inherited from Control.)

System_CAPS_pubproperty

Gets or sets a reference to the template that contains this control. (Inherited from Control.)

System_CAPS_pubproperty

Gets the virtual directory of the Page or UserControl that contains the current server control.(Inherited from Control.)

System_CAPS_pubproperty

Gets the unique, hierarchically qualified identifier for the server control.(Inherited from Control.)

System_CAPS_pubproperty

Gets or sets a value that indicates whether the control checks client input from the browser for potentially dangerous values.(Inherited from Control.)

System_CAPS_protproperty

Gets a dictionary of state information that allows you to save and restore the view state of a server control across multiple requests for the same page.(Inherited from Control.)

System_CAPS_protproperty

Gets a value that indicates whether the StateBag object is case-insensitive.(Inherited from Control.)

System_CAPS_pubproperty

Gets or sets the view-state mode of this control.(Inherited from Control.)

System_CAPS_pubproperty

Gets or sets a value that indicates whether a server control is rendered as UI on the page.(Inherited from Control.)

NameDescription
System_CAPS_protmethod AddedControl

Called after a child control is added to the collection of the Control object.(Inherited from Control.)

System_CAPS_protmethod AddParsedSubObject

Notifies the server control that an element, either XML or HTML, was parsed, and adds the element to the server control's ControlCollection object.(Inherited from Control.)

System_CAPS_pubmethod ApplyStyleSheetSkin

Applies the style properties defined in the page style sheet to the control.(Inherited from Control.)

System_CAPS_protmethod BeginRenderTracing

Begins design-time tracing of rendering data.(Inherited from Control.)

System_CAPS_protmethod BuildProfileTree

This API supports the product infrastructure and is not intended to be used directly from your code. Gathers information about the server control and delivers it to the property to be displayed when tracing is enabled for the page.(Inherited from Control.)

System_CAPS_protmethod ClearCachedClientID

This API supports the product infrastructure and is not intended to be used directly from your code. Sets the cached value to null.(Inherited from Control.)

System_CAPS_protmethod ClearChildControlState

Deletes the control-state information for the server control's child controls. (Inherited from Control.)

System_CAPS_protmethod ClearChildState

Deletes the view-state and control-state information for all the server control's child controls.(Inherited from Control.)

System_CAPS_protmethod ClearChildViewState

Deletes the view-state information for all the server control's child controls.(Inherited from Control.)

System_CAPS_protmethod ClearEffectiveClientIDMode

This API supports the product infrastructure and is not intended to be used directly from your code. Sets the property of the current control instance and of any child controls to Inherit.(Inherited from Control.)

System_CAPS_protmethod CreateChildControls

Called by the ASP.NET page framework to notify server controls that use composition-based implementation to create any child controls they contain in preparation for posting back or rendering.(Inherited from Control.)

System_CAPS_protmethod CreateControlCollection

Returns an EmptyControlCollection object, indicating that the Substitution control does not support child controls.(Overrides ControlCreateControlCollection.)

System_CAPS_pubmethod DataBind

Binds a data source to the invoked server control and all its child controls.(Inherited from Control.)

System_CAPS_protmethod DataBind

Binds a data source to the invoked server control and all its child controls with an option to raise the DataBinding event. (Inherited from Control.)

System_CAPS_protmethod DataBindChildren

Binds a data source to the server control's child controls.(Inherited from Control.)

System_CAPS_pubmethod Dispose

Enables a server control to perform final clean up before it is released from memory.(Inherited from Control.)

System_CAPS_protmethod EndRenderTracing

Ends design-time tracing of rendering data.(Inherited from Control.)

System_CAPS_protmethod EnsureChildControls

Determines whether the server control contains child controls. If it does not, it creates child controls.(Inherited from Control.)

System_CAPS_protmethod EnsureID

Creates an identifier for controls that do not have an identifier assigned.(Inherited from Control.)

System_CAPS_pubmethod Equals

Determines whether the specified object is equal to the current object.(Inherited from Object.)

System_CAPS_protmethod Finalize

Allows an object to try to free resources and perform other cleanup operations before it is reclaimed by garbage collection.(Inherited from Object.)

System_CAPS_pubmethod FindControl

Searches the current naming container for a server control with the specified id parameter.(Inherited from Control.)

System_CAPS_protmethod FindControl

This API supports the product infrastructure and is not intended to be used directly from your code. Searches the current naming container for a server control with the specified id and an integer, specified in the pathOffset parameter, which aids in the search. You should not override this version of the FindControl method.(Inherited from Control.)

System_CAPS_pubmethod Focus

Sets input focus to a control.(Inherited from Control.)

System_CAPS_protmethod GetDesignModeState

This API supports the product infrastructure and is not intended to be used directly from your code. Gets design-time data for a control.(Inherited from Control.)

System_CAPS_pubmethod GetHashCode

Serves as the default hash function. (Inherited from Object.)

System_CAPS_pubmethod GetRouteUrl

Gets the URL that corresponds to a set of route parameters.(Inherited from Control.)

System_CAPS_pubmethod GetRouteUrl

Gets the URL that corresponds to a set of route parameters.(Inherited from Control.)

System_CAPS_pubmethod GetRouteUrl

Gets the URL that corresponds to a set of route parameters and a route name.(Inherited from Control.)

System_CAPS_pubmethod GetRouteUrl

Gets the URL that corresponds to a set of route parameters and a route name.(Inherited from Control.)

System_CAPS_pubmethod GetType

Gets the Type of the current instance.(Inherited from Object.)

System_CAPS_pubmethod GetUniqueIDRelativeTo

Returns the prefixed portion of the property of the specified control.(Inherited from Control.)

System_CAPS_pubmethod HasControls

Determines if the server control contains any child controls.(Inherited from Control.)

System_CAPS_protmethod HasEvents

Returns a value indicating whether events are registered for the control or any child controls.(Inherited from Control.)

System_CAPS_protmethod IsLiteralContent

This API supports the product infrastructure and is not intended to be used directly from your code. Determines if the server control holds only literal content.(Inherited from Control.)

System_CAPS_protmethod LoadControlState

Restores control-state information from a previous page request that was saved by the SaveControlState method.(Inherited from Control.)

System_CAPS_protmethod LoadViewState

Restores view-state information from a previous page request that was saved by the SaveViewState method.(Inherited from Control.)

System_CAPS_protmethod MapPathSecure

Retrieves the physical path that a virtual path, either absolute or relative, maps to.(Inherited from Control.)

System_CAPS_protmethod MemberwiseClone

Creates a shallow copy of the current Object.(Inherited from Object.)

System_CAPS_protmethod OnBubbleEvent

Determines whether the event for the server control is passed up the page's UI server control hierarchy.(Inherited from Control.)

System_CAPS_protmethod OnDataBinding

Raises the DataBinding event.(Inherited from Control.)

System_CAPS_protmethod OnInit

Raises the Init event.(Inherited from Control.)

System_CAPS_protmethod OnLoad

Raises the Load event.(Inherited from Control.)

System_CAPS_protmethod OnPreRender

Raises the PreRender event.(Overrides ControlOnPreRender.)

System_CAPS_protmethod OnUnload

Raises the Unload event.(Inherited from Control.)

System_CAPS_protmethod OpenFile

Gets a Stream used to read a file.(Inherited from Control.)

System_CAPS_protmethod RaiseBubbleEvent

Assigns any sources of the event and its information to the control's parent.(Inherited from Control.)

System_CAPS_protmethod RemovedControl

Called after a child control is removed from the collection of the Control object.(Inherited from Control.)

System_CAPS_protmethod Render

Sends server control content to a provided HtmlTextWriter object, which writes the content to be rendered on the clien(Overrides ControlRender.)

System_CAPS_protmethod RenderChildren

Outputs the content of a server control's children to a provided HtmlTextWriter object, which writes the content to be rendered on the client.(Inherited from Control.)

System_CAPS_pubmethod RenderControl

Outputs server control content to a provided HtmlTextWriter object and stores tracing information about the control if tracing is enabled.(Inherited from Control.)

System_CAPS_protmethod RenderControl

Outputs server control content to a provided HtmlTextWriter object using a provided ControlAdapter object.(Inherited from Control.)

System_CAPS_protmethod ResolveAdapter

Gets the control adapter responsible for rendering the specified control.(Inherited from Control.)

System_CAPS_pubmethod ResolveClientUrl

Gets a URL that can be used by the browser.(Inherited from Control.)

System_CAPS_pubmethod ResolveUrl

Converts a URL into one that is usable on the requesting client.(Inherited from Control.)

System_CAPS_protmethod SaveControlState

Saves any server control state changes that have occurred since the time the page was posted back to the server.(Inherited from Control.)

System_CAPS_protmethod SaveViewState

Saves any server control view-state changes that have occurred since the time the page was posted back to the server.(Inherited from Control.)

System_CAPS_protmethod SetDesignModeState

Sets design-time data for a control.(Inherited from Control.)

System_CAPS_pubmethod SetRenderMethodDelegate

This API supports the product infrastructure and is not intended to be used directly from your code. Assigns an event handler delegate to render the server control and its content into its parent control.(Inherited from Control.)

System_CAPS_pubmethod SetTraceData

Sets trace data for design-time tracing of rendering data, using the trace data key and the trace data value.(Inherited from Control.)

System_CAPS_pubmethod SetTraceData

Sets trace data for design-time tracing of rendering data, using the traced object, the trace data key, and the trace data value.(Inherited from Control.)

System_CAPS_pubmethod ToString

Returns a string that represents the current object.(Inherited from Object.)

System_CAPS_protmethod TrackViewState

Causes tracking of view-state changes to the server control so they can be stored in the server control's StateBag object. This object is accessible through the property.(Inherited from Control.)

NameDescription
System_CAPS_pubevent DataBinding

Occurs when the server control binds to a data source.(Inherited from Control.)

System_CAPS_pubevent Disposed

Occurs when a server control is released from memory, which is the last stage of the server control lifecycle when an ASP.NET page is requested.(Inherited from Control.)

System_CAPS_pubevent Init

Occurs when the server control is initialized, which is the first step in its lifecycle.(Inherited from Control.)

System_CAPS_pubevent Load

Occurs when the server control is loaded into the Page object.(Inherited from Control.)

System_CAPS_pubevent PreRender

Occurs after the Control object is loaded but prior to rendering.(Inherited from Control.)

System_CAPS_pubevent Unload

Occurs when the server control is unloaded from memory.(Inherited from Control.)

NameDescription
System_CAPS_pubinterface System_CAPS_privmethod IControlDesignerAccessorGetDesignModeState

For a description of this member, see IControlDesignerAccessorGetDesignModeState.(Inherited from Control.)

System_CAPS_pubinterface System_CAPS_privmethod IControlDesignerAccessorSetDesignModeState

For a description of this member, see IControlDesignerAccessorSetDesignModeState. (Inherited from Control.)

System_CAPS_pubinterface System_CAPS_privmethod IControlDesignerAccessorSetOwnerControl

This API supports the product infrastructure and is not intended to be used directly from your code. For a description of this member, see IControlDesignerAccessorSetOwnerControl. (Inherited from Control.)

System_CAPS_pubinterface System_CAPS_privmethod IParserAccessorAddParsedSubObject

For a description of this member, see IParserAccessorAddParsedSubObject. (Inherited from Control.)

System_CAPS_pubinterface System_CAPS_privproperty

For a description of this member, see . (Inherited from Control.)

System_CAPS_pubinterface System_CAPS_privproperty

For a description of this member, see . (Inherited from Control.)

System_CAPS_pubinterface System_CAPS_privproperty

For a description of this member, see . (Inherited from Control.)

System_CAPS_pubinterface System_CAPS_privproperty

For a description of this member, see . (Inherited from Control.)

System_CAPS_pubinterface System_CAPS_privproperty

For a description of this member, see . (Inherited from Control.)

System_CAPS_pubinterface System_CAPS_privproperty

For a description of this member, see . (Inherited from Control.)

NameDescription
System_CAPS_pubmethod FindDataSourceControl

Returns the data source that is associated with the data control for the specified control.(Defined by DynamicDataExtensions.)

System_CAPS_pubmethod FindFieldTemplate

Returns the field template for the specified column in the specified control's naming container.(Defined by DynamicDataExtensions.)

System_CAPS_pubmethod FindMetaTable

Returns the metatable object for the containing data control.(Defined by DynamicDataExtensions.)

In this topic:

  • Introduction

  • Declarative Syntax

Use the Substitution control to specify a section on an output-cached Web page where you want dynamic content substituted for the control. The Substitution control offers a simplified solution to partial page caching for pages where the majority of the content is cached. You can output-cache the entire page, and then use Substitution controls to specify the parts of the page that are exempt from caching. Cached regions execute only once and are replayed from the cache until the cache entry expires or is purged. Dynamic regions execute each time the page is requested. This caching model simplifies the code for pages that are primarily static, because you do not have to encapsulate the sections to cache in Web user controls. For example, this caching model is useful in a scenario where you have a page that contains static content, such as news stories, and an AdRotator control that displays advertisements. The news stories do not change, which means that they can be cached. However, each time a user requests the page, you want to display a new advertisement. The AdRotator control directly supports post-cache substitution and renders a new advertisement each time the page posts back, regardless of whether the page is cached.

System_CAPS_noteNote

You can place a Substitution control in a user control that is contained in a cached page. However, you cannot place a Substitution control in an output-cached user control.

When the Substitution control executes, it calls a method that returns a string. The string that the method returns is the content to display on the page at the location of the Substitution control. Use the property to specify the name of the callback method to invoke when the Substitution control executes. The callback method that you specify must be a static method on the page or user control that contains the Substitution control. The signature for the callback method must match the signature for an HttpResponseSubstitutionCallback delegate that takes an HttpContext parameter and returns a string.

To manipulate the output cache for a page, you can use the @ OutputCache directive, the HttpCachePolicy class, or the property. For more information on caching pages, see Caching ASP.NET Pages and Caching Portions of an ASP.NET Page.

As an alternative to using the Substitution control, you can also get substitution caching behavior using a HttpResponseSubstitutionCallback delegate. In addition, you can get substitution caching behavior on controls, such as the AdRotator control, that directly support this feature. For more information, see Dynamically Updating Portions of a Cached Page.

<asp:Substitution
    EnableTheming="True|False"
    EnableViewState="True|False"
    ID="string"
    MethodName="string"
    OnDataBinding="DataBinding event handler"
    OnDisposed="Disposed event handler"
    OnInit="Init event handler"
    OnLoad="Load event handler"
    OnPreRender="PreRender event handler"
    OnUnload="Unload event handler"
    runat="server"
    SkinID="string"
    Visible="True|False"
/>

The following code example demonstrates how to add a Substitution control declaratively to an output-cached Web page. When the page loads, the current date and time are displayed to the user in a label. This section of the page is cached and updated only every 60 seconds. When the Substitution control executes, it calls the GetCurrentDateTime method. The string returned by GetCurrentDateTime is displayed to the user. This section of the page is not cached and is updated each time the page is refreshed.

<%@ outputcache duration="60" varybyparam="none" %>
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN"
    "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<script runat="server" language="C#">  

  void Page_Load(object sender, System.EventArgs e)
  {
    // Display the current date and time in the label.
    // Output caching applies to this section of the page.
    CachedDateLabel.Text = DateTime.Now.ToString();    
  }

  // The Substitution control calls this method to retrieve
  // the current date and time. This section of the page
  // is exempt from output caching. 
  public static string GetCurrentDateTime (HttpContext context)
  {
    return DateTime.Now.ToString ();
  }

</script>

<html xmlns="http://www.w3.org/1999/xhtml" >
<head runat="server">
  <title>Substitution Class Example</title>
</head>
<body>
  <form id="form1" runat="server">

    <h3>Substitution Class Example</h3>  

    <p>This section of the page is not cached:</p>

    <asp:substitution id="Substitution1"
      methodname="GetCurrentDateTime"
      runat="Server">
    </asp:substitution>

    <br />

    <p>This section of the page is cached:</p>

    <asp:label id="CachedDateLabel"
      runat="Server">
    </asp:label>

    <br /><br />

    <asp:button id="RefreshButton"
      text="Refresh Page"
      runat="Server">
    </asp:button>     

  </form>
</body>
</html>
<%@ outputcache duration="60" varybyparam="none" %>
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN"
    "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<script runat="server" language="VB">  

  Sub Page_Load(ByVal sender As Object, ByVal e As System.EventArgs)
    ' Display the current date and time in the label.
    ' Output caching applies to this section of the page.
    CachedDateLabel.Text = DateTime.Now.ToString()
  End Sub

  ' The Substitution control calls this method to retrieve
  ' the current date and time. This section of the page
  ' is exempt from output caching. 
  Shared Function GetCurrentDateTime(ByVal context As HttpContext) As String
    Return DateTime.Now.ToString()
  End Function

</script>

<html xmlns="http://www.w3.org/1999/xhtml" >
<head id="Head1" runat="server">
  <title>Substitution Class Example</title>
</head>
<body>
  <form id="Form1" runat="server">

    <h3>Substitution Class Example</h3>  

    <p>This section of the page is not cached:</p>

    <asp:substitution id="Substitution1"
      methodname="GetCurrentDateTime"
      runat="Server">
    </asp:substitution>

    <br />

    <p>This section of the page is cached:</p>

    <asp:label id="CachedDateLabel"
      runat="Server">
    </asp:label>

    <br /><br />

    <asp:button id="RefreshButton"
      text="Refresh Page"
      runat="Server">
    </asp:button>     

  </form>
</body>
</html>
.NET Framework
Available since 2.0

Any public static ( Shared in Visual Basic) members of this type are thread safe. Any instance members are not guaranteed to be thread safe.

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