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., 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 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 event and set the event parameter's TOutputCacheCheckDependencyEventParameter::getIsValid property to indicate whether the cached data remains valid or not. One can also extend TOutputCache and override its 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 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 VaryBySession is set true. To variate the cached content by other factors, override 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 ContentCached property to determine whether the content is cached or not.
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,
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Method Summary |
protected
string
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Calculates the cache key.
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void
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Returns a value indicating whether body contents are allowed for this control.
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protected
string
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protected
ICacheDependency
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Returns the dependency of the data to be cached.
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string
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integer
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boolean
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boolean
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integer
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string
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boolean
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protected
void
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Performs the Init step for the control and all its child controls.
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protected
void
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Performs the Load step for the control and all its child controls.
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protected
void
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Loads state (viewstate and controlstate) into a control and its children.
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void
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This event is raised when the output cache is calculating cache key.
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void
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This event is raised when the output cache is checking cache dependency.
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protected
void
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Performs the PreRender step for the control and all its child controls.
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void
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registerAction
( string $context, string $funcName, array $funcParams)
Registers an action associated with the content being cached.
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void
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Renders the output cache control.
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protected
array
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Saves all control state (viewstate and controlstate) as a collection.
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void
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Sets the prefix of the cache key.
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void
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void
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Sets a value indicating whether cached output will be used on postback requests.
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void
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string
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Sets the names of the request parameters that should be used in calculating the cache key.
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void
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Methods Inherited From TControl |
TControl::addedControl(), TControl::addParsedObject(), TControl::addToPostDataLoader(), TControl::applyStyleSheetSkin(), TControl::autoBindProperty(), TControl::autoDataBindProperties(), TControl::bindProperty(), TControl::broadcastEvent(), TControl::bubbleEvent(), TControl::clearChildState(), TControl::clearControlState(), TControl::clearNamingContainer(), TControl::clearViewState(), TControl::convertUniqueIdToClientId(), TControl::createChildControls(), TControl::createControlCollection(), TControl::dataBind(), TControl::dataBindChildren(), TControl::dataBindProperties(), TControl::ensureChildControls(), TControl::findControl(), TControl::findControlsByID(), TControl::findControlsByType(), TControl::focus(), TControl::getAdapter(), TControl::getAllowChildControls(), TControl::getAttribute(), TControl::getAttributes(), TControl::getChildControlsCreated(), TControl::getClientID(), TControl::getControls(), TControl::getControlStage(), TControl::getControlState(), TControl::getCustomData(), TControl::getEnabled(), TControl::getEnableTheming(), TControl::getEnableViewState(), TControl::getHasAdapter(), TControl::getHasAttributes(), TControl::getHasChildInitialized(), TControl::getHasControls(), TControl::getHasInitialized(), TControl::getHasLoaded(), TControl::getHasLoadedPostData(), TControl::getHasPreRendered(), TControl::getID(), TControl::getNamingContainer(), TControl::getPage(), TControl::getParent(), TControl::getRegisteredObject(), TControl::getSkinID(), TControl::getSourceTemplateControl(), TControl::getTemplateControl(), TControl::getUniqueID(), TControl::getViewState(), TControl::getVisible(), TControl::hasAttribute(), TControl::initRecursive(), TControl::isDescendentOf(), TControl::isObjectRegistered(), TControl::loadRecursive(), TControl::loadState(), TControl::loadStateRecursive(), TControl::onDataBinding(), TControl::onInit(), TControl::onLoad(), TControl::onPreRender(), TControl::onUnload(), TControl::preRenderRecursive(), TControl::raiseBubbleEvent(), TControl::registerObject(), TControl::removeAttribute(), TControl::removedControl(), TControl::render(), TControl::renderChildren(), TControl::renderControl(), TControl::saveState(), TControl::saveStateRecursive(), TControl::setAdapter(), TControl::setAttribute(), TControl::setChildControlsCreated(), TControl::setControlStage(), TControl::setControlState(), TControl::setCustomData(), TControl::setEnabled(), TControl::setEnableTheming(), TControl::setEnableViewState(), TControl::setID(), TControl::setPage(), TControl::setSkinID(), TControl::setTemplateControl(), TControl::setViewState(), TControl::setVisible(), TControl::trackViewState(), TControl::traverseChildControls(), TControl::unbindProperty(), TControl::unloadRecursive(), TControl::unregisterObject(), TControl::__get()
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Methods Inherited From TComponent |
TComponent::addParsedObject(), TComponent::attachEventHandler(), TComponent::canGetProperty(), TComponent::canSetProperty(), TComponent::createdOnTemplate(), TComponent::detachEventHandler(), TComponent::evaluateExpression(), TComponent::evaluateStatements(), TComponent::getEventHandlers(), TComponent::getSubProperty(), TComponent::hasEvent(), TComponent::hasEventHandler(), TComponent::hasProperty(), TComponent::raiseEvent(), TComponent::setSubProperty(), TComponent::__get(), TComponent::__set()
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Method Details |
calculateCacheKey
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 VaryByParam. If 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.
Output |
string
| cache key |
Exception |
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getAllowChildControls
public void getAllowChildControls |
(boolean 0 ) |
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.
Input |
boolean | 0 | whether body contents are allowed for this control. |
Output |
Exception |
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getBaseCacheKey
protected string getBaseCacheKey |
() |
Output |
string
| basic cache key without variations |
Exception |
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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.
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getCacheModuleID
public string getCacheModuleID |
() |
Output |
string
| the ID of the cache module. Defaults to '', meaning the primary cache module is used. |
Exception |
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getCacheTime
public integer getCacheTime |
() |
Output |
integer
| the timestamp of the cached content. This is only valid if the content is being cached. |
Exception |
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getCachingPostBack
public boolean getCachingPostBack |
() |
Output |
boolean
| whether cached output will be used on postback requests. Defaults to false. |
Exception |
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getContentCached
public boolean getContentCached |
() |
Output |
boolean
| whether content enclosed is cached or not |
Exception |
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getDuration
public integer getDuration |
() |
Output |
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. |
Exception |
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getVaryByParam
public string getVaryByParam |
() |
Output |
string
| a semicolon-separated list of strings used to vary the output cache. Defaults to ''. |
Exception |
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getVaryBySession
public boolean getVaryBySession |
() |
Output |
boolean
| whether the content being cached should be differentiated according to user sessions. Defaults to false. |
Exception |
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initRecursive
protected void initRecursive |
(TControl $namingContainer ) |
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.
Input |
TControl | $namingContainer | the naming container control |
Output |
Exception |
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loadRecursive
protected void loadRecursive |
(TControl 0 ) |
Performs the Load step for the control and all its child controls.
This method overrides the parent implementation by setting up the stack of the output cache in the page. If the data is restored from cache, it also recovers the actions associated with the cached data. Only framework developers should use this method.
Input |
TControl | 0 | the naming container control |
Output |
Exception |
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loadStateRecursive
protected void loadStateRecursive |
(array &$state , boolean $needViewState ) |
Loads state (viewstate and controlstate) into a control and its children.
This method overrides the parent implementation by loading cached state if available. This method should only be used by framework developers.
Input |
array | &$state | the collection of the state |
boolean | $needViewState | whether the viewstate should be loaded |
Output |
Exception |
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onCalculateKey
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 of this event parameter will be appended to the default key calculation scheme.
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onCheckDependency
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 property of the event parameter (which defaults to true).
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preRenderRecursive
protected void preRenderRecursive |
(TControl 0 ) |
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.
Input |
TControl | 0 | the naming container control |
Output |
Exception |
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registerAction
public void 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.
Input |
string | $context | context of the action method. This is a property-path referring to the context object (e.g. Page, Page.ClientScript) |
string | $funcName | method name of the context object |
array | $funcParams | list of parameters to be passed to the action method |
Output |
Exception |
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render
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.
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saveStateRecursive
protected array saveStateRecursive |
(boolean $needViewState ) |
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.
Input |
boolean | $needViewState | whether the viewstate should be saved |
Output |
array
| the collection of the control state (including its children's state). |
Exception |
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setCacheKeyPrefix
public void setCacheKeyPrefix |
(string $value ) |
Sets the prefix of the cache key.
This method is used internally by TTemplate.
Input |
string | $value | key prefix |
Output |
Exception |
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setCacheModuleID
public void setCacheModuleID |
(string $value ) |
Input |
string | $value | the ID of the cache module. If empty, the primary cache module will be used. |
Output |
Exception |
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setCachingPostBack
public void 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.
Input |
boolean | $value | whether cached output will be used on postback requests. |
Output |
Exception |
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setDuration
public void setDuration |
(integer $value ) |
Input |
integer | $value | number of seconds that the data can remain in cache. If 0, it means data is not cached. |
Output |
Exception |
throws | TInvalidDataValueException if the value is smaller than 0. |
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setVaryByParam
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.
Input |
mixed | $value | |
Output |
string
| a semicolon-separated list of strings used to vary the output cache. |
Exception |
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setVaryBySession
public void setVaryBySession |
(boolean $value ) |
Input |
boolean | $value | whether the content being cached should be differentiated according to user sessions. |
Output |
Exception |
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Constant Details |
CACHE_ID_PREFIX
Type:
string
Value:
'prado:outputcache'
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