# Class yii\caching\TagDependency

Inheritance | yii\caching\TagDependency » yii\caching\Dependency » yii\base\BaseObject
Implements | yii\base\Configurable
Available since version | 2.0
Source Code | https://github.com/yiisoft/yii2/blob/master/framework/caching/TagDependency.php

TagDependency associates a cached data item with one or multiple $tags.

By calling invalidate(), you can invalidate all cached data items that are associated with the specified tag name(s).

    // setting multiple cache keys to store data forever and tagging them with "user-123"
    Yii::$app->cache->set('user_42_profile', '', 0, new TagDependency(['tags' => 'user-123']));
    Yii::$app->cache->set('user_42_stats', '', 0, new TagDependency(['tags' => 'user-123']));

    // invalidating all keys tagged with "user-123"
    TagDependency::invalidate(Yii::$app->cache, 'user-123');

For more details and usage information on Cache, see the guide article on caching.

## Public Properties

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Property | Type | Description | Defined By
--- | --- | --- | ---
$data | mixed | The dependency data that is saved in cache and later is compared with the latest dependency data. | yii\caching\Dependency
$reusable | boolean | Whether this dependency is reusable or not. | yii\caching\Dependency
$tags | string|array | A list of tag names for this dependency. | yii\caching\TagDependency

## Public Methods

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Method | Description | Defined By
--- | --- | ---
__call() | Calls the named method which is not a class method. | yii\base\BaseObject
__construct() | Constructor. | yii\base\BaseObject
__get() | Returns the value of an object property. | yii\base\BaseObject
__isset() | Checks if a property is set, i.e. defined and not null. | yii\base\BaseObject
__set() | Sets value of an object property. | yii\base\BaseObject
__unset() | Sets an object property to null. | yii\base\BaseObject
canGetProperty() | Returns a value indicating whether a property can be read. | yii\base\BaseObject
canSetProperty() | Returns a value indicating whether a property can be set. | yii\base\BaseObject
className() | Returns the fully qualified name of this class. | yii\base\BaseObject
evaluateDependency() | Evaluates the dependency by generating and saving the data related with dependency. | yii\caching\Dependency
getHasChanged() | Returns a value indicating whether the dependency has changed. | yii\caching\Dependency
hasMethod() | Returns a value indicating whether a method is defined. | yii\base\BaseObject
hasProperty() | Returns a value indicating whether a property is defined. | yii\base\BaseObject
init() | Initializes the object. | yii\base\BaseObject
invalidate() | Invalidates all of the cached data items that are associated with any of the specified $tags. | yii\caching\TagDependency
isChanged() | Checks whether the dependency is changed. | yii\caching\TagDependency
resetReusableData() | Resets all cached data for reusable dependencies. | yii\caching\Dependency

## Protected Methods

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Method | Description | Defined By
--- | --- | ---
generateDependencyData() | Generates the data needed to determine if dependency has been changed. | yii\caching\TagDependency
generateReusableHash() | Generates a unique hash that can be used for retrieving reusable dependency data. | yii\caching\Dependency
getTimestamps() | Returns the timestamps for the specified tags. | yii\caching\TagDependency
touchKeys() | Generates the timestamp for the specified cache keys. | yii\caching\TagDependency

## Property Details

$tags public property

A list of tag names for this dependency. For a single tag, you may specify it as a string.

public string|array $tags = []

## Method Details

generateDependencyData() protected method

Generates the data needed to determine if dependency has been changed.

This method does nothing in this class.

protected mixed generateDependencyData ( $cache )
$cache | yii\caching\CacheInterface | The cache component that is currently evaluating this dependency
return | mixed | The data needed to determine if dependency has been changed.

getTimestamps() protected method

Returns the timestamps for the specified tags.

protected array getTimestamps ( $cache, $tags )
$cache | yii\caching\CacheInterface |
$tags | string[] |
return | array | The timestamps indexed by the specified tags.

invalidate() public static method

Invalidates all of the cached data items that are associated with any of the specified $tags.

public static void invalidate ( $cache, $tags )
$cache | yii\caching\CacheInterface | The cache component that caches the data items
$tags | string|array |

isChanged() public method (available since version 2.0.11)

Checks whether the dependency is changed.

public boolean isChanged ( $cache )
$cache | yii\caching\CacheInterface | The cache component that is currently evaluating this dependency
return | boolean | Whether the dependency has changed.

touchKeys() protected static method

Generates the timestamp for the specified cache keys.

protected static array touchKeys ( $cache, $keys )
$cache | yii\caching\CacheInterface |
$keys | string[] |
return | array | The timestamp indexed by cache keys