ASP.NET Directives

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ASP.NET directives are instructions to specify optional settings, such as registering a custom control and page language. These settings describe how the web forms (.aspx) or user controls (.ascx) pages are processed by the .Net framework.

The syntax for declaring a directive is:
<%@  directive_name attribute=value  [attribute=value]  %>

In this section, we will just introduce the ASP.NET directives and we will use most of these directives throughout the tutorials.

The Application Directive


The Application directive defines application-specific attributes. It is provided at the top of the global.aspx file.

The basic syntax of Application directive is:
<%@ Application Language="C#" %>

The attributes of the Application directive are:



















AttributesDescription
InheritsThe name of the class from which to inherit.
DescriptionThe text description of the application. Parsers and compilers ignore this.
LanguageThe language used in code blocks.

The Assembly Directive


The Assembly directive links an assembly to the page or the application at parse time. This could appear either in the global.asax file for application-wide linking, in the page file, a user control file for linking to a page or user control.

The basic syntax of Assembly directive is:
<%@ Assembly Name ="myassembly" %>

The attributes of the Assembly directive are:















AttributesDescription
NameThe name of the assembly to be linked.
SrcThe path to the source file to be linked and compiled dynamically.

The Control Directive


The control directive is used with the user controls and appears in the user control (.ascx) files.

The basic syntax of Control directive is:
<%@ Control Language="C#"  EnableViewState="false" %>

The attributes of the Control directive are:















































AttributesDescription
AutoEventWireupThe Boolean value that enables or disables automatic association of events to handlers.
ClassNameThe file name for the control.
DebugThe Boolean value that enables or disables compiling with debug symbols.
DescriptionThe text description of the control page, ignored by compiler.
EnableViewStateThe Boolean value that indicates whether view state is maintained across page requests.
ExplicitFor VB language, tells the compiler to use option explicit mode.
InheritsThe class from which the control page inherits.
LanguageThe language for code and script.
SrcThe filename for the code-behind class.
StrictFor VB language, tells the compiler to use the option strict mode.

The Implements Directive


The Implement directive indicates that the web page, master page or user control page must implement the specified .Net framework interface.

The basic syntax for implements directive is:
<%@ Implements  Interface="interface_name" %>

The Import Directive


The Import directive imports a namespace into a web page, user control page of application. If the Import directive is specified in the global.asax file, then it is applied to the entire application. If it is in a page of user control page, then it is applied to that page or control.

The basic syntax for import directive is:
<%@ namespace="System.Drawing" %>

The Master Directive


The Master directive specifies a page file as being the mater page.

The basic syntax of sample MasterPage directive is:
<%@ MasterPage Language="C#"  AutoEventWireup="true"  CodeFile="SiteMater.master.cs" Inherits="SiteMaster"  %>

The MasterType Directive


The MasterType directive assigns a class name to the Master property of a page, to make it strongly typed.

The basic syntax of MasterType directive is:
<%@ MasterType attribute="value"[attribute="value" ...]  %>

The OutputCache Directive


The OutputCache directive controls the output caching policies of a web page or a user control.

The basic syntax of OutputCache directive is:
<%@ OutputCache Duration="15" VaryByParam="None"  %>

The Page Directive


The Page directive defines the attributes specific to the page file for the page parser and the compiler.

The basic syntax of Page directive is:
<%@ Page Language="C#"  AutoEventWireup="true" CodeFile="Default.aspx.cs"  Inherits="_Default"  Trace="true" %>

The attributes of the Page directive are:











































































AttributesDescription
AutoEventWireupThe Boolean value that enables or disables page events that are being automatically bound to methods; for example, Page_Load.
BufferThe Boolean value that enables or disables HTTP response buffering.
ClassNameThe class name for the page.
ClientTargetThe browser for which the server controls should render content.
CodeFileThe name of the code behind file.
DebugThe Boolean value that enables or disables compilation with debug symbols.
DescriptionThe text description of the page, ignored by the parser.
EnableSessionStateIt enables, disables, or makes session state read-only.
EnableViewStateThe Boolean value that enables or disables view state across page requests.
ErrorPageURL for redirection if an unhandled page exception occurs.
InheritsThe name of the code behind or other class.
LanguageThe programming language for code.
SrcThe file name of the code behind class.
TraceIt enables or disables tracing.
TraceModeIt indicates how trace messages are displayed, and sorted by time or category.
TransactionIt indicates if transactions are supported.
ValidateRequestThe Boolean value that indicates whether all input data is validated against a hardcoded list of values.

The PreviousPageType Directive


The PreviousPageType directive assigns a class to a page, so that the page is strongly typed.

The basic syntax for a sample PreviousPagetype directive is:
<%@ PreviousPageType attribute="value"[attribute="value" ...]   %>

The Reference Directive


The Reference directive indicates that another page or user control should be compiled and linked to the current page.

The basic syntax of Reference directive is:
<%@ Reference Page ="somepage.aspx" %>

The Register Directive


The Register derivative is used for registering the custom server controls and user controls.

The basic syntax of Register directive is:
<%@ Register Src="~/footer.ascx" TagName="footer" TagPrefix="Tfooter" %>

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