$key = 'demo';
$data = $cache->get($key);
if ($data === false) {
    // ...generate $data here...
    $cache->set($key, $data, $duration, $dependency);
}

$cache['foo'] = 'some data';
echo $cache['foo'];

public integer $defaultDuration = 0

public string $keyPrefix = null

public null|array|false $serializer = null

add() public method

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

Nothing will be done if the cache already contains the key.

public boolean add ( $key, $value, $duration = 0, $dependency = null )
$key	mixed	A key identifying the value to be cached. This can be a simple string or a complex data structure consisting of factors representing the key.
$value	mixed	The value to be cached
$duration	integer	The number of seconds in which the cached value will expire. 0 means never expire.
$dependency	yii\caching\Dependency	Dependency of the cached item. If the dependency changes, the corresponding value in the cache will be invalidated when it is fetched via get(). This parameter is ignored if $serializer is false.
return	boolean	Whether the value is successfully stored into cache

addValue() protected abstract 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 abstract boolean addValue ( $key, $value, $duration )
$key	string	The key identifying the value to be cached
$value	mixed	The value to be cached. Most often it's a string. If you have disabled $serializer, it could be something else.
$duration	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

addValues() protected method

Adds multiple key-value pairs to cache.

The default implementation calls addValue() multiple times add values one by one. If the underlying cache storage supports multi-add, this method should be overridden to exploit that feature.

protected array addValues ( $data, $duration )
$data	array	Array where key corresponds to cache key while value is the value stored.
$duration	integer	The number of seconds in which the cached values will expire. 0 means never expire.
return	array	Array of failed keys

buildKey() public method

Builds a normalized cache key from a given key.

If the given key is a string containing alphanumeric characters only and no more than 32 characters, then the key will be returned back prefixed with $keyPrefix. Otherwise, a normalized key is generated by serializing the given key, applying MD5 hashing, and prefixing with $keyPrefix.

public string buildKey ( $key )
$key	mixed	The key to be normalized
return	string	The generated cache key

delete() public method

Deletes a value with the specified key from cache

public boolean delete ( $key )
$key	mixed	A key identifying the value to be deleted from cache. This can be a simple string or a complex data structure consisting of factors representing the key.
return	boolean	If no error happens during deletion

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

exists() public method

Checks whether a specified key exists in the cache.

This can be faster than getting the value from the cache if the data is big. In case a cache does not support this feature natively, this method will try to simulate it but has no performance improvement over getting it. Note that this method does not check whether the dependency associated with the cached data, if there is any, has changed. So a call to get() may return false while exists returns true.

public boolean exists ( $key )
$key	mixed	A key identifying the cached value. This can be a simple string or a complex data structure consisting of factors representing the key.
return	boolean	True if a value exists in cache, false if the value is not in the cache or expired.

flush() public method

Deletes all values from cache.

Be careful of performing this operation if the cache is shared among multiple applications.

public boolean flush ( )
return	boolean	Whether the flush operation was successful.

flushValues() protected abstract method

Deletes all values from cache.

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

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

get() public method

Retrieves a value from cache with a specified key.

public mixed get ( $key )
$key	mixed	A key identifying the cached value. This can be a simple string or a complex data structure consisting of factors representing the key.
return	mixed	The value stored in cache, false if the value is not in the cache, expired, or the dependency associated with the cached data has changed.

getOrSet() public method (available since version 2.0.11)

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.

Usage example:

public function getTopProducts($count = 10) {
    $cache = $this->cache; // Could be Yii::$app->cache
    return $cache->getOrSet(['top-n-products', 'n' => $count], function ($cache) use ($count) {
        return Products::find()->mostPopular()->limit(10)->all();
    }, 1000);
}

public mixed getOrSet ( $key, $callable, $duration = null, $dependency = null )
$key	mixed	A key identifying the value to be cached. This can be a simple string or a complex data structure consisting of factors representing the key.
$callable	callable|Closure	The callable or closure that will be used to generate a value to be cached. In case $callable returns false, the value will not be cached.
$duration	integer	Default duration in seconds before the cache will expire. If not set, $defaultDuration value will be used.
$dependency	yii\caching\Dependency	Dependency of the cached item. If the dependency changes, the corresponding value in the cache will be invalidated when it is fetched via get(). This parameter is ignored if $serializer is false.
return	mixed	Result of $callable execution

getValue() protected abstract 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 abstract mixed|false getValue ( $key )
$key	string	A unique key identifying the cached value
return	mixed|false	The value stored in cache, false if the value is not in the cache or expired. Most often value is a string. If you have disabled $serializer, it could be something else.

getValues() protected method

Retrieves multiple values from cache with the specified keys.

The default implementation calls getValue() multiple times to retrieve the cached values one by one. If the underlying cache storage supports multiget, this method should be overridden to exploit that feature.

protected array getValues ( $keys )
$keys	array	A list of keys identifying the cached values
return	array	A list of cached values indexed by the keys

madd() public method

Deprecated This method is an alias for multiAdd() and will be removed in 2.1.0.

Stores multiple items in cache. Each item contains a value identified by a key.

If the cache already contains such a key, the existing value and expiration time will be preserved.

public array madd ( $items, $duration = 0, $dependency = null )
$items	array	The items to be cached, as key-value pairs.
$duration	integer	Default number of seconds in which the cached values will expire. 0 means never expire.
$dependency	yii\caching\Dependency	Dependency of the cached items. If the dependency changes, the corresponding values in the cache will be invalidated when it is fetched via get(). This parameter is ignored if $serializer is false.
return	array	Array of failed keys

mget() public method

Deprecated This method is an alias for multiGet() and will be removed in 2.1.0.

Retrieves multiple values from cache with the specified keys.

Some caches (such as memcache, apc) allow retrieving multiple cached values at the same time, which may improve the performance. In case a cache does not support this feature natively, this method will try to simulate it.

public array mget ( $keys )
$keys	string[]	List of string keys identifying the cached values
return	array	List of cached values corresponding to the specified keys. The array is returned in terms of (key, value) pairs. If a value is not cached or expired, the corresponding array value will be false.

mset() public method

Deprecated This method is an alias for multiSet() and will be removed in 2.1.0.

Stores multiple items in cache. Each item contains a value identified by a key.

If the cache already contains such a key, the existing value and expiration time will be replaced with the new ones, respectively.

public array mset ( $items, $duration = 0, $dependency = null )
$items	array	The items to be cached, as key-value pairs.
$duration	integer	Default number of seconds in which the cached values will expire. 0 means never expire.
$dependency	yii\caching\Dependency	Dependency of the cached items. If the dependency changes, the corresponding values in the cache will be invalidated when it is fetched via get(). This parameter is ignored if $serializer is false.
return	array	Array of failed keys

multiAdd() public method (available since version 2.0.7)

Stores multiple items in cache. Each item contains a value identified by a key.

If the cache already contains such a key, the existing value and expiration time will be preserved.

public array multiAdd ( $items, $duration = 0, $dependency = null )
$items	array	The items to be cached, as key-value pairs.
$duration	integer	Default number of seconds in which the cached values will expire. 0 means never expire.
$dependency	yii\caching\Dependency	Dependency of the cached items. If the dependency changes, the corresponding values in the cache will be invalidated when it is fetched via get(). This parameter is ignored if $serializer is false.
return	array	Array of failed keys

multiGet() public method (available since version 2.0.7)

Retrieves multiple values from cache with the specified keys.

Some caches (such as memcache, apc) allow retrieving multiple cached values at the same time, which may improve the performance. In case a cache does not support this feature natively, this method will try to simulate it.

public array multiGet ( $keys )
$keys	string[]	List of string keys identifying the cached values
return	array	List of cached values corresponding to the specified keys. The array is returned in terms of (key, value) pairs. If a value is not cached or expired, the corresponding array value will be false.

multiSet() public method (available since version 2.0.7)

Stores multiple items in cache. Each item contains a value identified by a key.

If the cache already contains such a key, the existing value and expiration time will be replaced with the new ones, respectively.

public array multiSet ( $items, $duration = 0, $dependency = null )
$items	array	The items to be cached, as key-value pairs.
$duration	integer	Default number of seconds in which the cached values will expire. 0 means never expire.
$dependency	yii\caching\Dependency	Dependency of the cached items. If the dependency changes, the corresponding values in the cache will be invalidated when it is fetched via get(). This parameter is ignored if $serializer is false.
return	array	Array of failed keys

offsetExists() public method

Returns whether there is a cache entry with a specified key.

This method is required by the interface ArrayAccess.

public boolean offsetExists ( $key )
$key	string	A key identifying the cached value

offsetGet() public method

Retrieves the value from cache with a specified key.

This method is required by the interface ArrayAccess.

public mixed offsetGet ( $key )
$key	string	A key identifying the cached value
return	mixed	The value stored in cache, false if the value is not in the cache or expired.

offsetSet() public method

Stores the value identified by a key into cache.

If the cache already contains such a key, the existing value will be replaced with the new ones. To add expiration and dependencies, use the set() method. This method is required by the interface ArrayAccess.

public void offsetSet ( $key, $value )
$key	string	The key identifying the value to be cached
$value	mixed	The value to be cached

offsetUnset() public method

Deletes the value with the specified key from cache This method is required by the interface ArrayAccess.

public void offsetUnset ( $key )
$key	string	The key of the value to be deleted

set() public method

Stores a value identified by a key into cache.

If the cache already contains such a key, the existing value and expiration time will be replaced with the new ones, respectively.

public boolean set ( $key, $value, $duration = null, $dependency = null )
$key	mixed	A key identifying the value to be cached. This can be a simple string or a complex data structure consisting of factors representing the key.
$value	mixed	The value to be cached
$duration	integer	Default duration in seconds before the cache will expire. If not set, default $defaultDuration value is used.
$dependency	yii\caching\Dependency	Dependency of the cached item. If the dependency changes, the corresponding value in the cache will be invalidated when it is fetched via get(). This parameter is ignored if $serializer is false.
return	boolean	Whether the value is successfully stored into cache

setValue() protected abstract 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 abstract boolean setValue ( $key, $value, $duration )
$key	string	The key identifying the value to be cached
$value	mixed	The value to be cached. Most often it's a string. If you have disabled $serializer, it could be something else.
$duration	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

setValues() protected method

Stores multiple key-value pairs in cache.

The default implementation calls setValue() multiple times store values one by one. If the underlying cache storage supports multi-set, this method should be overridden to exploit that feature.

protected array setValues ( $data, $duration )
$data	array	Array where key corresponds to cache key while value is the value stored
$duration	integer	The number of seconds in which the cached values will expire. 0 means never expire.
return	array	Array of failed keys