CDbCacheDependency

Package	system.caching.dependencies
Inheritance	class CDbCacheDependency » CCacheDependency » CComponent
Implements	ICacheDependency
Since	1.0
Source Code	framework/caching/dependencies/CDbCacheDependency.php

CDbCacheDependency represents a dependency based on the query result of a SQL statement.

If the query result (a scalar) changes, the dependency is considered as changed. To specify the SQL statement, set sql property. The connectionID property specifies the ID of a CDbConnection application component. It is this DB connection that is used to perform the query.

Public Properties

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Property	Type	Description	Defined By
connectionID	string	the ID of a CDbConnection application component.	CDbCacheDependency
dependentData	mixed	the data used to determine if dependency has been changed.	CCacheDependency
hasChanged	boolean	whether the dependency has changed.	CCacheDependency
params	array	parameters (name=>value) to be bound to the SQL statement specified by sql.	CDbCacheDependency
reuseDependentData	boolean	Whether this dependency is reusable or not.	CCacheDependency
sql	string	the SQL statement whose result is used to determine if the dependency has been changed.	CDbCacheDependency

Protected Properties

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Property	Type	Description	Defined By
dbConnection	CDbConnection	the DB connection instance	CDbCacheDependency

Public Methods

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Method	Description	Defined By
__call()	Calls the named method which is not a class method.	CComponent
__construct()	Constructor.	CDbCacheDependency
__get()	Returns a property value, an event handler list or a behavior based on its name.	CComponent
__isset()	Checks if a property value is null.	CComponent
__set()	Sets value of a component property.	CComponent
__sleep()	PHP sleep magic method.	CDbCacheDependency
__unset()	Sets a component property to be null.	CComponent
asa()	Returns the named behavior object.	CComponent
attachBehavior()	Attaches a behavior to this component.	CComponent
attachBehaviors()	Attaches a list of behaviors to the component.	CComponent
attachEventHandler()	Attaches an event handler to an event.	CComponent
canGetProperty()	Determines whether a property can be read.	CComponent
canSetProperty()	Determines whether a property can be set.	CComponent
detachBehavior()	Detaches a behavior from the component.	CComponent
detachBehaviors()	Detaches all behaviors from the component.	CComponent
detachEventHandler()	Detaches an existing event handler.	CComponent
disableBehavior()	Disables an attached behavior.	CComponent
disableBehaviors()	Disables all behaviors attached to this component.	CComponent
enableBehavior()	Enables an attached behavior.	CComponent
enableBehaviors()	Enables all behaviors attached to this component.	CComponent
evaluateDependency()	Evaluates the dependency by generating and saving the data related with dependency.	CCacheDependency
evaluateExpression()	Evaluates a PHP expression or callback under the context of this component.	CComponent
getDependentData()	Returns the data used to determine if dependency has been changed. This data is available after evaluateDependency is called.	CCacheDependency
getEventHandlers()	Returns the list of attached event handlers for an event.	CComponent
getHasChanged()	Returns whether the dependency has changed.	CCacheDependency
hasEvent()	Determines whether an event is defined.	CComponent
hasEventHandler()	Checks whether the named event has attached handlers.	CComponent
hasProperty()	Determines whether a property is defined.	CComponent
raiseEvent()	Raises an event.	CComponent
resetReusableData()	Resets cached data for reusable dependencies.	CCacheDependency

Protected Methods

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Method	Description	Defined By
generateDependentData()	Generates the data needed to determine if dependency has been changed.	CDbCacheDependency
getDbConnection()	Returns the DB connection instance	CDbCacheDependency

Property Details

connectionID property

public string $connectionID;

the ID of a CDbConnection application component. Defaults to 'db'.

dbConnection property read-only

protected CDbConnection getDbConnection()

the DB connection instance

params property (available since v1.1.4)

public array $params;

parameters (name=>value) to be bound to the SQL statement specified by sql.

sql property

public string $sql;

the SQL statement whose result is used to determine if the dependency has been changed. Note, the SQL statement should return back a single value.

Method Details

__construct() method

public void __construct(string $sql=NULL)
$sql	string	the SQL statement whose result is used to determine if the dependency has been changed.

Source Code: framework/caching/dependencies/CDbCacheDependency.php#46 (show)


public function __construct($sql=null)
{
    $this->sql=$sql;
}

Constructor.

__sleep() method

public array __sleep()
{return}	array

Source Code: framework/caching/dependencies/CDbCacheDependency.php#56 (show)


public function __sleep()
{
    $this->_db=null;
    return array_keys((array)$this);
}

PHP sleep magic method. This method ensures that the database instance is set null because it contains resource handles.

generateDependentData() method

protected mixed generateDependentData()
{return}	mixed	the data needed to determine if dependency has been changed.

Source Code: framework/caching/dependencies/CDbCacheDependency.php#68 (show)


protected function generateDependentData()
{
    if($this->sql!==null)
    {
        $db=$this->getDbConnection();
        $command=$db->createCommand($this->sql);
        if(is_array($this->params))
        {
            foreach($this->params as $name=>$value)
                $command->bindValue($name,$value);
        }
        if($db->queryCachingDuration>0)
        {
            // temporarily disable and re-enable query caching
            $duration=$db->queryCachingDuration;
            $db->queryCachingDuration=0;
            $result=$command->queryRow();
            $db->queryCachingDuration=$duration;
        }
        else
            $result=$command->queryRow();
        return $result;
    }
    else
        throw new CException(Yii::t('yii','CDbCacheDependency.sql cannot be empty.'));
}

Generates the data needed to determine if dependency has been changed. This method returns the value of the global state.

getDbConnection() method

protected CDbConnection getDbConnection()
{return}	CDbConnection	the DB connection instance

Source Code: framework/caching/dependencies/CDbCacheDependency.php#99 (show)


protected function getDbConnection()
{
    if($this->_db!==null)
        return $this->_db;
    else
    {
        if(($this->_db=Yii::app()->getComponent($this->connectionID)) instanceof CDbConnection)
            return $this->_db;
        else
            throw new CException(Yii::t('yii','CDbCacheDependency.connectionID "{id}" is invalid. Please make sure it refers to the ID of a CDbConnection application component.',
                array('{id}'=>$this->connectionID)));
    }
}

User Contributed Notes