DbQueryDependency

API reference › yii › caching › DbQueryDependency

class	`yii\caching\DbQueryDependency`
Extends	`Dependency` » `yii\base\BaseObject`
Implements	`yii\base\Configurable`
Since	2.0.12
Source	`framework/caching/DbQueryDependency.php`

DbQueryDependency represents a dependency based on the query result of an QueryInterface instance.

If the query result changes, the dependency is considered as changed. The query is specified via the $query property.

Object of any class which matches QueryInterface can be used, so this dependency can be used not only with regular relational databases but with MongoDB, Redis and so on as well.

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

Properties

Property	Type	Description	Defined by
`$data`	`mixed`	The dependency data that is saved in cache and later is compared with the latest dependency data. Default: `null`.	`Dependency`
`$db`	`string\|array\|object`	The application component ID of the database connection, connection object or its array configuration. Default: `null`.	`DbQueryDependency`
`$method`	`string\|callable\|null`	Method which should be invoked in over the `$query` object. Default: `null`.	`DbQueryDependency`
`$query`	`yii\db\QueryInterface`	The query which result is used to determine if the dependency has been changed. Default: `null`.	`DbQueryDependency`
`$reusable`	`bool`	Whether this dependency is reusable or not. Default: `false`.	`Dependency`

Methods

Method	Description	Defined by
`__construct()`	Constructor.	`yii\base\BaseObject`
`__call()`	Calls the named method which is not a class method.	`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()` static	Returns the fully qualified name of this class.	`yii\base\BaseObject`
`evaluateDependency()`	Evaluates the dependency by generating and saving the data related with dependency.	`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`
`isChanged()`	Checks whether the dependency is changed.	`Dependency`
`resetReusableData()` static	Resets all cached data for reusable dependencies.	`Dependency`
`generateDependencyData()` protected	Generates the data needed to determine if dependency is changed.	`DbQueryDependency`
`generateReusableHash()` protected	Generates a unique hash that can be used for retrieving reusable dependency data.	`Dependency`

Property details

$db

public string|array|object $db = null

The application component ID of the database connection, connection object or its array configuration.

This field can be left blank, allowing query to determine connection automatically.

$method

public string|callable|null $method = null

Method which should be invoked in over the $query object.

If specified as a string an own query method with such name will be invoked, passing $db value as its first argument. For example: exists, all.

This field can be specified as a PHP callback of following signature:

function (QueryInterface $query, mixed $db) {
    //return mixed;
}

If not set - QueryInterface::one() will be used.

$query

public yii\db\QueryInterface $query = null

The query which result is used to determine if the dependency has been changed.

Actual query method to be invoked is determined by $method.

Method details

generateDependencyData()

protected function generateDependencyData(yii\caching\CacheInterface $cache): mixed

Generates the data needed to determine if dependency is changed.

This method returns the query result.

Parameters

Parameter	Type	Description
`$cache`	`CacheInterface`	The cache component that is currently evaluating this dependency

Returns

mixed: The data needed to determine if dependency has been changed.

Throws

yii\base\InvalidConfigException: on invalid configuration.