Zend Framework 101: Zend_Registry

Accessing the Registry

There are three key functions in accessing the registry: writing a variable, reading a variable, and checking if a value exists in the registry.

Writing to the Registry

To write to the registry, use the Zend_Registry::set() static method. This method accepts two arguments: the name of the item as it will be referred to in the registry, and the value to store in the registry. Listing 1 shows an example of this.

<?php
    require_once('Zend/Registry.php');
 
    $name = 'Quentin Zervaas';
    Zend_Registry::set('name', $name);
?>

You can write complex objects (that is, any variable), not just simple variables like strings or integers.

Checking if A Value Exists

To check if a particular value exists in the registry, use the Zend_Registry::isRegistered() static method. This method accepts the name of the variable to check for as its only argument. If the variable exists true is returned, otherwise false is returned. Listing 2 shows an example of this.

<?php
    require_once('Zend/Registry.php');
 
    if (Zend_Registry::isRegistered('name')) {
        // value is in registry
    }
    else {
        // value is not in registry
    }
?>

Retrieving Registry Values

To retrieve a value from the registry, use the Zend_Registry::get() method. This method accepts the name of variable to retrieve. If the value doesn't exist then the Zend_Exception exception is thrown. Handling the exception is a good alternative to using isRegistered() to check for a value existing in the registry.

Listing 3 shows an example of retrieving a value from the registry and handling the case where the value doesn't exist.

<?php
    require_once('Zend/Registry.php');
 
    try {
        $name = Zend_Registry::get('name');
    }
    catch (Exception $ex) {
        // entry with key 'name' does not exist
    }
?>

Once you've retrieved the value from the registry you can then proceed to use it as normal.

• Next: Access the Registry Using Array Syntax