# Class yii\mongodb\Cache

Inheritance | yii\mongodb\Cache » yii\caching\Cache » yii\base\Component » yii\base\BaseObject
Implements | yii\base\Configurable, yii\caching\CacheInterface
Available since version | 2.0
Source Code | https://github.com/yiisoft/yii2-mongodb/blob/master/Cache.php

Cache implements a cache application component by storing cached data in a MongoDB.

By default, Cache stores session data in a MongoDB collection named 'cache' inside the default database. This collection is better to be pre-created with fields 'id' and 'expire' indexed. The collection name can be changed by setting $cacheCollection.

Please refer to yii\caching\Cache for common cache operations that are supported by Cache.

The following example shows how you can configure the application to use Cache:

    'cache' => [
        'class' => 'yii\mongodb\Cache',
        // 'db' => 'mymongodb',
        // 'cacheCollection' => 'my_cache',
    ]

## Public Properties

Hide inherited properties

Property | Type | Description | Defined By
--- | --- | --- | ---
$behaviors | yii\base\Behavior[] | List of behaviors attached to this component. This property is read-only. | yii\base\Component
$cacheCollection | string|array | The name of the MongoDB collection that stores the cache data. | yii\mongodb\Cache
$db | yii\mongodb\Connection|array|string | The MongoDB connection object or the application component ID of the MongoDB connection. | yii\mongodb\Cache
$defaultDuration | integer | Default duration in seconds before a cache entry will expire. | yii\caching\Cache
$gcProbability | integer | The probability (parts per million) that garbage collection (GC) should be performed when storing a piece of data in the cache. | yii\mongodb\Cache
$keyPrefix | string | A string prefixed to every cache key so that it is unique globally in the whole cache storage. | yii\caching\Cache
$serializer | null|array|false | The functions used to serialize and unserialize cached data. | yii\caching\Cache

## Public Methods

Hide inherited methods

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
add() | Stores a value identified by a key into cache if the cache does not contain this key. | yii\caching\Cache
attachBehavior() | Attaches a behavior to this component. | yii\base\Component
attachBehaviors() | Attaches a list of behaviors to the component. | yii\base\Component
behaviors() | Returns a list of behaviors that this component should behave as. | yii\base\Component
buildKey() | Builds a normalized cache key from a given key. | yii\caching\Cache
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
delete() | Deletes a value with the specified key from cache. | yii\caching\Cache
detachBehavior() | Detaches a behavior from the component. | yii\base\Component
detachBehaviors() | Detaches all behaviors from the component. | yii\base\Component
ensureBehaviors() | Makes sure that the behaviors declared in behaviors() are attached to this component. | yii\base\Component
exists() | Checks whether a specified key exists in the cache. | yii\caching\Cache
flush() | Deletes all values from cache. | yii\caching\Cache
gc() | Removes the expired data values. | yii\mongodb\Cache
get() | Retrieves a value from cache with a specified key. | yii\caching\Cache
getBehavior() | Returns the named behavior object. | yii\base\Component
getBehaviors() | Returns all behaviors attached to this component. | yii\base\Component
getOrSet() | Method combines both set() and get() methods to retrieve value identified by a $key, or to store the result of $callable execution if there is no cache available for the $key. | yii\caching\Cache
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 Cache component. | yii\mongodb\Cache
madd() | Stores multiple items in cache. Each item contains a value identified by a key. | yii\caching\Cache
mget() | Retrieves multiple values from cache with the specified keys. | yii\caching\Cache
mset() | Stores multiple items in cache. Each item contains a value identified by a key. | yii\caching\Cache
multiAdd() | Stores multiple items in cache. Each item contains a value identified by a key. | yii\caching\Cache
multiGet() | Retrieves multiple values from cache with the specified keys. | yii\caching\Cache
multiSet() | Stores multiple items in cache. Each item contains a value identified by a key. | yii\caching\Cache
off() | Detaches an existing event handler from this component. | yii\base\Component
offsetExists() | Returns whether there is a cache entry with a specified key. | yii\caching\Cache
offsetGet() | Retrieves the value from cache with a specified key. | yii\caching\Cache
offsetSet() | Stores the value identified by a key into cache. | yii\caching\Cache
offsetUnset() | Deletes the value with the specified key from cache This method is required by the interface ArrayAccess. | yii\caching\Cache
on() | Attaches an event handler to an event. | yii\base\Component
set() | Stores a value identified by a key into cache. | yii\caching\Cache
trigger() | Triggers an event. | yii\base\Component

## Protected Methods

Hide inherited methods

Method | Description | Defined By
--- | --- | ---
addValue() | Stores a value identified by a key into cache if the cache does not contain this key. | yii\mongodb\Cache
addValues() | Adds multiple key-value pairs to cache. | yii\caching\Cache
deleteValue() | Deletes a value with the specified key from cache This method should be implemented by child classes to delete the data from actual cache storage. | yii\mongodb\Cache
flushValues() | Deletes all values from cache. | yii\mongodb\Cache
getValue() | Retrieves a value from cache with a specified key. | yii\mongodb\Cache
getValues() | Retrieves multiple values from cache with the specified keys. | yii\caching\Cache
setValue() | Stores a value identified by a key in cache. | yii\mongodb\Cache
setValues() | Stores multiple key-value pairs in cache. | yii\caching\Cache

## Property Details

$cacheCollection public property

The name of the MongoDB collection that stores the cache data. Please refer to yii\mongodb\Connection::getCollection() on how to specify this parameter. This collection is better to be pre-created with fields 'id' and 'expire' indexed.

public string|array $cacheCollection = 'cache'
$db public property

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

public yii\mongodb\Connection|array|string $db = 'mongodb'
$gcProbability public property

The probability (parts per million) that garbage collection (GC) should be performed when storing a piece of data in the cache. Defaults to 100, meaning 0.01% chance. This number should be between 0 and 1000000. A value 0 meaning no GC will be performed at all.

public integer $gcProbability = 100

## Method Details

addValue() protected method

Stores a value identified by a key into cache if the cache does not contain this key.

This method should be implemented by child classes to store the data in specific cache storage.

protected boolean addValue ( $key, $value, $expire )
$key | string | The key identifying the value to be cached
$value | string | The value to be cached
$expire | integer | The number of seconds in which the cached value will expire. 0 means never expire.
return | boolean | True if the value is successfully stored into cache, false otherwise

deleteValue() protected method

Deletes a value with the specified key from cache This method should be implemented by child classes to delete the data from actual cache storage.

protected boolean deleteValue ( $key )
$key | string | The key of the value to be deleted
return | boolean | If no error happens during deletion

flushValues() protected method

Deletes all values from cache.

Child classes may implement this method to realize the flush operation.

protected boolean flushValues ( )
return | boolean | Whether the flush operation was successful.

gc() public method

Removes the expired data values.

public void gc ( $force = false )
$force | boolean | Whether to enforce the garbage collection regardless of $gcProbability. Defaults to false, meaning the actual deletion happens with the probability as specified by $gcProbability.

getValue() protected method

Retrieves a value from cache with a specified key.

This method should be implemented by child classes to retrieve the data from specific cache storage.

protected string|boolean getValue ( $key )
$key | string | A unique key identifying the cached value
return | string|boolean | The value stored in cache, false if the value is not in the cache or expired.

init() public method

Initializes the Cache component.

This method will initialize the $db property to make sure it refers to a valid MongoDB connection.

public void init ( )
throws | yii\base\InvalidConfigException | if $db is invalid.

setValue() protected method

Stores a value identified by a key in cache.

This method should be implemented by child classes to store the data in specific cache storage.

protected boolean setValue ( $key, $value, $expire )
$key | string | The key identifying the value to be cached
$value | string | The value to be cached
$expire | integer | The number of seconds in which the cached value will expire. 0 means never expire.
return | boolean | True if the value is successfully stored into cache, false otherwise