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Class TOutputCache

TOutputCache class.

TOutputCache enables caching a portion of a Web page, also known as partial caching. The content being cached can be either static or dynamic.

To use TOutputCache, simply enclose the content to be cached within the TOutputCache component tag on a template, e.g.,

<com:TOutputCache>
  content to be cached
</com:TOutputCache>

where content to be cached can be static text and/or component tags.

The validity of the cached content is determined based on two factors: the setDuration Duration and the cache dependency. The former specifies the number of seconds that the data can remain valid in cache (defaults to 60s), while the latter specifies conditions that the cached data depends on. If a dependency changes, (e.g. relevant data in DB are updated), the cached data will be invalidated.

There are two ways to specify cache dependency. One may write event handlers to respond to the onCheckDependency OnCheckDependency event and set the event parameter's TOutputCacheCheckDependencyEventParameter::getIsValid IsValid property to indicate whether the cached data remains valid or not. One can also extend TOutputCache and override its TOutputCache::getCacheDependency() function. While the former is easier to use, the latter offers more extensibility.

The content fetched from cache may be variated with respect to some parameters. It supports variation with respect to request parameters, which is specified by setVaryByParam VaryByParam property. If a specified request parameter is different, a different version of cached content is used. This is extremely useful if a page's content may be variated according to some GET parameters. The content being cached may also be variated with user sessions if setVaryBySession VaryBySession is set true. To variate the cached content by other factors, override TOutputCache::calculateCacheKey() method.

Output caches can be nested. An outer cache takes precedence over an inner cache. This means, if the content cached by the inner cache expires or is invalidated, while that by the outer cache not, the outer cached content will be used.

Note, TOutputCache is effective only for non-postback page requests and when cache module is enabled.

Do not attempt to address child controls of TOutputCache when the cached content is to be used. Use getContentCached ContentCached property to determine whether the content is cached or not.

TComponent
Extended by TApplicationComponent
Extended by TControl implements IRenderable, IBindable
Extended by TOutputCache implements INamingContainer
Package: System\Web\UI\WebControls
Copyright: Copyright © 2005-2014 PradoSoft
License: http://www.pradosoft.com/license/
Author: Qiang Xue <qiang.xue@gmail.com>
Since: 3.1
Located at Web/UI/WebControls/TOutputCache.php
Methods summary
public boolean
# getAllowChildControls( )

Returns a value indicating whether body contents are allowed for this control. This method overrides the parent implementation by checking if cached content is available or not. If yes, it returns false, otherwise true.

Returns a value indicating whether body contents are allowed for this control. This method overrides the parent implementation by checking if cached content is available or not. If yes, it returns false, otherwise true.

Returns

boolean
whether body contents are allowed for this control. Defaults to true.

Overrides

TControl::getAllowChildControls()
protected
# initRecursive( TControl $namingContainer = null )

Performs the Init step for the control and all its child controls. This method overrides the parent implementation by setting up the stack of the output cache in the page. Only framework developers should use this method.

Performs the Init step for the control and all its child controls. This method overrides the parent implementation by setting up the stack of the output cache in the page. Only framework developers should use this method.

Parameters

$namingContainer
TControl
the naming container control

Overrides

TControl::initRecursive()
protected
# loadRecursive( )

Performs the Load step for the control and all its child controls. This method overrides the parent implementation by setting up the stack of the output cache in the page. If the data is restored from cache, it also recovers the actions associated with the cached data. Only framework developers should use this method.

Performs the Load step for the control and all its child controls. This method overrides the parent implementation by setting up the stack of the output cache in the page. If the data is restored from cache, it also recovers the actions associated with the cached data. Only framework developers should use this method.

Overrides

TControl::loadRecursive()
protected
# preRenderRecursive( )

Performs the PreRender step for the control and all its child controls. This method overrides the parent implementation by setting up the stack of the output cache in the page. Only framework developers should use this method.

Performs the PreRender step for the control and all its child controls. This method overrides the parent implementation by setting up the stack of the output cache in the page. Only framework developers should use this method.

Overrides

TControl::preRenderRecursive()
protected
# loadStateRecursive( array & $state, boolean $needViewState = true )

Loads state (viewstate and controlstate) into a control and its children. This method overrides the parent implementation by loading cached state if available. This method should only be used by framework developers.

Loads state (viewstate and controlstate) into a control and its children. This method overrides the parent implementation by loading cached state if available. This method should only be used by framework developers.

Parameters

$state
array
the collection of the state
$needViewState
boolean
whether the viewstate should be loaded

Overrides

TControl::loadStateRecursive()
protected array &
# saveStateRecursive( boolean $needViewState = true )

Saves all control state (viewstate and controlstate) as a collection. This method overrides the parent implementation by saving state into cache if needed. This method should only be used by framework developers.

Saves all control state (viewstate and controlstate) as a collection. This method overrides the parent implementation by saving state into cache if needed. This method should only be used by framework developers.

Parameters

$needViewState
boolean
whether the viewstate should be saved

Returns

array
the collection of the control state (including its children's state).

Overrides

TControl::saveStateRecursive()
public
# registerAction( string $context, string $funcName, array $funcParams )

Registers an action associated with the content being cached. The registered action will be replayed if the content stored in the cache is served to end-users.

Registers an action associated with the content being cached. The registered action will be replayed if the content stored in the cache is served to end-users.

Parameters

$context
string
context of the action method. This is a property-path referring to the context object (e.g. Page, Page.ClientScript)
$funcName
string
method name of the context object
$funcParams
array
list of parameters to be passed to the action method
public
# getCacheKey( )
protected string
# calculateCacheKey( )

Calculates the cache key. The key is calculated based on the unique ID of this control and the request parameters specified via setVaryByParam VaryByParam. If getVaryBySession VaryBySession is true, the session ID will also participate in the key calculation. This method may be overriden to support other variations in the calculated cache key.

Calculates the cache key. The key is calculated based on the unique ID of this control and the request parameters specified via setVaryByParam VaryByParam. If getVaryBySession VaryBySession is true, the session ID will also participate in the key calculation. This method may be overriden to support other variations in the calculated cache key.

Returns

string
cache key
protected string
# getBaseCacheKey( )

Returns

string
basic cache key without variations
public string
# getCacheModuleID( )

Returns

string
the ID of the cache module. Defaults to '', meaning the primary cache module is used.
public
# setCacheModuleID( string $value )

Parameters

$value
string
the ID of the cache module. If empty, the primary cache module will be used.
public
# setCacheKeyPrefix( string $value )

Sets the prefix of the cache key. This method is used internally by TTemplate.

Sets the prefix of the cache key. This method is used internally by TTemplate.

Parameters

$value
string
key prefix
public integer
# getCacheTime( )

Returns

integer
the timestamp of the cached content. This is only valid if the content is being cached.

Since

3.1.1
protected ICacheDependency
# getCacheDependency( )

Returns the dependency of the data to be cached. The default implementation simply returns null, meaning no specific dependency. This method may be overriden to associate the data to be cached with additional dependencies.

Returns the dependency of the data to be cached. The default implementation simply returns null, meaning no specific dependency. This method may be overriden to associate the data to be cached with additional dependencies.

Returns

ICacheDependency
public boolean
# getContentCached( )

Returns

boolean
whether content enclosed is cached or not
public integer
# getDuration( )

Returns

integer
number of seconds that the data can remain in cache. Defaults to 60 seconds. Note, if cache dependency changes or cache space is limited, the data may be purged out of cache earlier.
public
# setDuration( integer $value )

Parameters

$value
integer
number of seconds that the data can remain in cache. If 0, it means data is not cached.

Throws

TInvalidDataValueException
if the value is smaller than 0.
public string
# getVaryByParam( )

Returns

string
a semicolon-separated list of strings used to vary the output cache. Defaults to ''.
public string
# setVaryByParam( mixed $value )

Sets the names of the request parameters that should be used in calculating the cache key. The names should be concatenated by semicolons. By setting this value, the output cache will use different cached data for each different set of request parameter values.

Sets the names of the request parameters that should be used in calculating the cache key. The names should be concatenated by semicolons. By setting this value, the output cache will use different cached data for each different set of request parameter values.

Returns

string
a semicolon-separated list of strings used to vary the output cache.
public boolean
# getVaryBySession( )

Returns

boolean
whether the content being cached should be differentiated according to user sessions. Defaults to false.
public
# setVaryBySession( boolean $value )

Parameters

$value
boolean
whether the content being cached should be differentiated according to user sessions.
public boolean
# getCachingPostBack( )

Returns

boolean
whether cached output will be used on postback requests. Defaults to false.
public
# setCachingPostBack( boolean $value )

Sets a value indicating whether cached output will be used on postback requests. By default, this is disabled. Be very cautious when enabling it. If the cached content including interactive user controls such as TTextBox, TDropDownList, your page may fail to render on postbacks.

Sets a value indicating whether cached output will be used on postback requests. By default, this is disabled. Be very cautious when enabling it. If the cached content including interactive user controls such as TTextBox, TDropDownList, your page may fail to render on postbacks.

Parameters

$value
boolean
whether cached output will be used on postback requests.
public
# onCheckDependency( TOutputCacheCheckDependencyEventParameter $param )

This event is raised when the output cache is checking cache dependency. An event handler may be written to check customized dependency conditions. The checking result should be saved by setting TOutputCacheCheckDependencyEventParameter::setIsValid IsValid property of the event parameter (which defaults to true).

This event is raised when the output cache is checking cache dependency. An event handler may be written to check customized dependency conditions. The checking result should be saved by setting TOutputCacheCheckDependencyEventParameter::setIsValid IsValid property of the event parameter (which defaults to true).

Parameters

$param
TOutputCacheCheckDependencyEventParameter
event parameter
public
# onCalculateKey( TOutputCacheCalculateKeyEventParameter $param )

This event is raised when the output cache is calculating cache key. By varying cache keys, one can obtain different versions of cached content. An event handler may be written to add variety of the key calculation. The value set in TOutputCacheCalculateKeyEventParameter::setCacheKey CacheKey of this event parameter will be appended to the default key calculation scheme.

This event is raised when the output cache is calculating cache key. By varying cache keys, one can obtain different versions of cached content. An event handler may be written to add variety of the key calculation. The value set in TOutputCacheCalculateKeyEventParameter::setCacheKey CacheKey of this event parameter will be appended to the default key calculation scheme.

Parameters

$param
TOutputCacheCalculateKeyEventParameter
event parameter
public
# render( THtmlWriter $writer )

Renders the output cache control. This method overrides the parent implementation by capturing the output from its child controls and saving it into cache, if output cache is needed.

Renders the output cache control. This method overrides the parent implementation by capturing the output from its child controls and saving it into cache, if output cache is needed.

Parameters

$writer
THtmlWriter

Overrides

TControl::render()
Methods inherited from TControl
__construct(), __get(), addParsedObject(), addToPostDataLoader(), addedControl(), applyStyleSheetSkin(), autoBindProperty(), autoDataBindProperties(), bindProperty(), broadcastEvent(), bubbleEvent(), clearChildState(), clearControlState(), clearNamingContainer(), clearViewState(), convertUniqueIdToClientId(), createChildControls(), createControlCollection(), dataBind(), dataBindChildren(), dataBindProperties(), ensureChildControls(), findControl(), findControlsByID(), findControlsByType(), focus(), getAdapter(), getAttribute(), getAttributes(), getChildControlsCreated(), getClientID(), getControlStage(), getControlState(), getControls(), getCustomData(), getEnableTheming(), getEnableViewState(), getEnabled(), getHasAdapter(), getHasAttributes(), getHasChildInitialized(), getHasControls(), getHasInitialized(), getHasLoaded(), getHasLoadedPostData(), getHasPreRendered(), getID(), getIsSkinApplied(), getNamingContainer(), getPage(), getParent(), getRegisteredObject(), getSkinID(), getSourceTemplateControl(), getTemplateControl(), getUniqueID(), getViewState(), getVisible(), hasAttribute(), isDescendentOf(), isObjectRegistered(), loadState(), onDataBinding(), onInit(), onLoad(), onPreRender(), onUnload(), raiseBubbleEvent(), registerObject(), removeAttribute(), removedControl(), renderChildren(), renderControl(), saveState(), setAdapter(), setAttribute(), setChildControlsCreated(), setControlStage(), setControlState(), setCustomData(), setEnableTheming(), setEnableViewState(), setEnabled(), setID(), setPage(), setSkinID(), setTemplateControl(), setViewState(), setVisible(), trackViewState(), traverseChildControls(), unbindProperty(), unloadRecursive(), unregisterObject()
Methods inherited from TApplicationComponent
getApplication(), getRequest(), getResponse(), getService(), getSession(), getUser(), publishAsset(), publishFilePath()
Methods inherited from TComponent
__call(), __destruct(), __isset(), __set(), __sleep(), __unset(), __wakeup(), asa(), attachBehavior(), attachBehaviors(), attachClassBehavior(), attachEventHandler(), canGetProperty(), canSetProperty(), clearBehaviors(), createdOnTemplate(), detachBehavior(), detachBehaviors(), detachClassBehavior(), detachEventHandler(), disableBehavior(), disableBehaviors(), enableBehavior(), enableBehaviors(), evaluateExpression(), evaluateStatements(), fxAttachClassBehavior(), fxDetachClassBehavior(), getAutoGlobalListen(), getBehaviorsEnabled(), getClassHierarchy(), getEventHandlers(), getListeningToGlobalEvents(), getSubProperty(), hasEvent(), hasEventHandler(), hasProperty(), isa(), listen(), raiseEvent(), setSubProperty(), unlisten()
Constants summary
string CACHE_ID_PREFIX 'prado:outputcache'
#
Constants inherited from TControl
AUTOMATIC_ID_PREFIX, CLIENT_ID_SEPARATOR, CS_CHILD_INITIALIZED, CS_CONSTRUCTED, CS_INITIALIZED, CS_LOADED, CS_PRERENDERED, CS_STATE_LOADED, ID_FORMAT, ID_SEPARATOR, IS_CHILD_CREATED, IS_CREATING_CHILD, IS_DISABLE_THEMING, IS_DISABLE_VIEWSTATE, IS_ID_SET, IS_SKIN_APPLIED, IS_STYLESHEET_APPLIED, RF_ADAPTER, RF_AUTO_BINDINGS, RF_CHILD_STATE, RF_CONTROLS, RF_CONTROLSTATE, RF_DATA_BINDINGS, RF_EVENTS, RF_NAMED_CONTROLS, RF_NAMED_CONTROLS_ID, RF_NAMED_OBJECTS, RF_SKIN_ID
Constants inherited from TComponent
GLOBAL_RAISE_EVENT_LISTENER
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