# Class yii\widgets\FragmentCache

Inheritance | yii\widgets\FragmentCache » yii\base\Widget » yii\base\Component » yii\base\BaseObject
Implements | yii\base\Configurable, yii\base\DynamicContentAwareInterface, yii\base\ViewContextInterface
Uses Traits | yii\base\DynamicContentAwareTrait
Available since version | 2.0
Source Code | https://github.com/yiisoft/yii2/blob/master/framework/widgets/FragmentCache.php

FragmentCache is used by yii\base\View to provide caching of page fragments.

## Public Properties

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Property | Type | Description | Defined By
--- | --- | --- | ---
$autoIdPrefix | string | The prefix to the automatically generated widget IDs. | yii\base\Widget
$behaviors | yii\base\Behavior[] | List of behaviors attached to this component. This property is read-only. | yii\base\Component
$cache | yii\caching\CacheInterface|array|string | The cache object or the application component ID of the cache object. | yii\widgets\FragmentCache
$cachedContent | string|false | The cached content. False is returned if valid content is not found in the cache. This property is read-only. | yii\widgets\FragmentCache
$counter | integer | A counter used to generate $id for widgets. | yii\base\Widget
$dependency | array|yii\caching\Dependency | The dependency that the cached content depends on. | yii\widgets\FragmentCache
$duration | integer | Number of seconds that the data can remain valid in cache. | yii\widgets\FragmentCache
$dynamicPlaceholders | array | A list of placeholders. | yii\base\DynamicContentAwareTrait
$enabled | boolean | Whether to enable the fragment cache. | yii\widgets\FragmentCache
$id | string|null | ID of the widget. Note that the type of this property differs in getter and setter. See getId() and setId() for details. | yii\base\Widget
$stack | yii\base\Widget[] | The widgets that are currently being rendered (not ended). | yii\base\Widget
$variations | string[]|string | List of factors that would cause the variation of the content being cached. | yii\widgets\FragmentCache
$view | yii\web\View | The view object that can be used to render views or view files. Note that the type of this property differs in getter and setter. See getView() and setView() for details. | yii\base\Widget
$viewPath | string | The directory containing the view files for this widget. This property is read-only. | yii\base\Widget

## Public Methods

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Method | Description | Defined By
--- | --- | ---
__call() | Calls the named method which is not a class method. | yii\base\Component
__clone() | This method is called after the object is created by cloning an existing one. | yii\base\Component
__construct() | Constructor. | yii\base\BaseObject
__get() | Returns the value of a component property. | yii\base\Component
__isset() | Checks if a property is set, i.e. defined and not null. | yii\base\Component
__set() | Sets the value of a component property. | yii\base\Component
__unset() | Sets a component property to be null. | yii\base\Component
addDynamicPlaceholder() | Adds a placeholder for dynamic content. | yii\base\DynamicContentAwareTrait
afterRun() | This method is invoked right after a widget is executed. | yii\base\Widget
attachBehavior() | Attaches a behavior to this component. | yii\base\Component
attachBehaviors() | Attaches a list of behaviors to the component. | yii\base\Component
beforeRun() | This method is invoked right before the widget is executed. | yii\base\Widget
begin() | Begins a widget. | yii\base\Widget
behaviors() | Returns a list of behaviors that this component should behave as. | yii\base\Component
canGetProperty() | Returns a value indicating whether a property can be read. | yii\base\Component
canSetProperty() | Returns a value indicating whether a property can be set. | yii\base\Component
className() | Returns the fully qualified name of this class. | yii\base\BaseObject
detachBehavior() | Detaches a behavior from the component. | yii\base\Component
detachBehaviors() | Detaches all behaviors from the component. | yii\base\Component
end() | Ends a widget. | yii\base\Widget
ensureBehaviors() | Makes sure that the behaviors declared in behaviors() are attached to this component. | yii\base\Component
getBehavior() | Returns the named behavior object. | yii\base\Component
getBehaviors() | Returns all behaviors attached to this component. | yii\base\Component
getCachedContent() | Returns the cached content if available. | yii\widgets\FragmentCache
getDynamicPlaceholders() | Returns a list of placeholders for dynamic content. This method is used internally to implement the content caching feature. | yii\base\DynamicContentAwareTrait
getId() | Returns the ID of the widget. | yii\base\Widget
getViewPath() | Returns the directory containing the view files for this widget. | yii\base\Widget
hasEventHandlers() | Returns a value indicating whether there is any handler attached to the named event. | yii\base\Component
hasMethod() | Returns a value indicating whether a method is defined. | yii\base\Component
hasProperty() | Returns a value indicating whether a property is defined for this component. | yii\base\Component
init() | Initializes the FragmentCache object. | yii\widgets\FragmentCache
off() | Detaches an existing event handler from this component. | yii\base\Component
on() | Attaches an event handler to an event. | yii\base\Component
render() | Renders a view. | yii\base\Widget
renderFile() | Renders a view file. | yii\base\Widget
run() | Marks the end of content to be cached. | yii\widgets\FragmentCache
setDynamicPlaceholders() | Sets a list of placeholders for dynamic content. This method is used internally to implement the content caching feature. | yii\base\DynamicContentAwareTrait
setId() | Sets the ID of the widget. | yii\base\Widget
setView() | Sets the view object to be used by this widget. | yii\base\Widget
trigger() | Triggers an event. | yii\base\Component
widget() | Creates a widget instance and runs it. | yii\base\Widget

## Protected Methods

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Method | Description | Defined By
--- | --- | ---
calculateKey() | Generates a unique key used for storing the content in cache. | yii\widgets\FragmentCache
getView() | Returns the view object that can be used to render views or view files using dynamic contents. | yii\base\DynamicContentAwareTrait
updateDynamicContent() | Replaces placeholders in $content with results of evaluated dynamic statements. | yii\base\DynamicContentAwareTrait

## Events

Hide inherited events

Event | Type | Description | Defined By
--- | --- | --- | ---
EVENT_AFTER_RUN | yii\base\WidgetEvent | An event raised right after executing a widget. (available since version 2.0.11) | yii\base\Widget
EVENT_BEFORE_RUN | yii\base\WidgetEvent | An event raised right before executing a widget. (available since version 2.0.11) | yii\base\Widget
EVENT_INIT | yii\base\Event | An event that is triggered when the widget is initialized via init(). (available since version 2.0.11) | yii\base\Widget

## Property Details

$cache public property

The cache object or the application component ID of the cache object. After the FragmentCache object is created, if you want to change this property, you should only assign it with a cache object. Starting from version 2.0.2, this can also be a configuration array for creating the object.

public yii\caching\CacheInterface|array|string $cache = 'cache'
$cachedContent public property

The cached content. False is returned if valid content is not found in the cache. This property is read-only.

public string|false $cachedContent = null
$dependency public property

The dependency that the cached content depends on. This can be either a yii\caching\Dependency object or a configuration array for creating the dependency object. For example,

    [
        'class' => 'yii\caching\DbDependency',
        'sql' => 'SELECT MAX(updated_at) FROM post',
    ]

would make the output cache depends on the last modified time of all posts. If any post has its modification time changed, the cached content would be invalidated.

public array|yii\caching\Dependency $dependency = null
$duration public property

Number of seconds that the data can remain valid in cache. Use 0 to indicate that the cached data will never expire.

public integer $duration = 60
$enabled public property

Whether to enable the fragment cache. You may use this property to turn on and off the fragment cache according to specific setting (e.g. enable fragment cache only for GET requests).

public boolean $enabled = true
$variations public property

List of factors that would cause the variation of the content being cached. Each factor is a string representing a variation (e.g. the language, a GET parameter). The following variation setting will cause the content to be cached in different versions according to the current application language:

    [
        Yii::$app->language,
    ]

public string[]|string $variations = null

## Method Details

calculateKey() protected method

Generates a unique key used for storing the content in cache.

The key generated depends on both $id and $variations.

protected mixed calculateKey ( )
return | mixed | A valid cache key

getCachedContent() public method

Returns the cached content if available.

public string|false getCachedContent ( )
return | string|false | The cached content. False is returned if valid content is not found in the cache.

init() public method

Initializes the FragmentCache object.

public void init ( )

run() public method

Marks the end of content to be cached.

Content displayed before this method call and after init() will be captured and saved in cache. This method does nothing if valid content is already found in cache.

public void run ( )