cakephp/src/Datasource/ConnectionManager.php

<?php
/**
 * CakePHP(tm) : Rapid Development Framework (http://cakephp.org)
 * Copyright (c) Cake Software Foundation, Inc. (http://cakefoundation.org)
 *
 * Licensed under The MIT License
 * For full copyright and license information, please see the LICENSE.txt
 * Redistributions of files must retain the above copyright notice.
 *
 * @copyright     Copyright (c) Cake Software Foundation, Inc. (http://cakefoundation.org)
 * @link          http://cakephp.org CakePHP(tm) Project
 * @since         0.10.0
 * @license       http://www.opensource.org/licenses/mit-license.php MIT License
 */
namespace Cake\Datasource;

use Cake\Core\StaticConfigTrait;
use Cake\Datasource\ConnectionRegistry;
use Cake\Datasource\Error\MissingDatasourceConfigException;

/**
 * Manages and loads instances of Connection
 *
 * Provides an interface to loading and creating connection objects. Acts as
 * a registry for the connections defined in an application.
 *
 * Provides an interface for loading and enumerating connections defined in
 * config/app.php
 */
class ConnectionManager {

	use StaticConfigTrait {
		config as protected _config;
	}

/**
 * A map of connection aliases.
 *
 * @var array
 */
	protected static $_aliasMap = [];

/**
 * The ConnectionRegistry used by the manager.
 *
 * @var \Cake\Datasource\ConnectionRegistry
 */
	protected static $_registry = null;

/**
 * Configure a new connection object.
 *
 * The connection will not be constructed until it is first used.
 *
 * @param string|array $key The name of the connection config, or an array of multiple configs.
 * @param array $config An array of name => config data for adapter.
 * @return mixed null when adding configuration and an array of configuration data when reading.
 * @throws \Cake\Error\Exception When trying to modify an existing config.
 * @see \Cake\Core\StaticConfigTrait::config()
 */
	public static function config($key, $config = null) {
		if (is_array($config)) {
			$config['name'] = $key;
		}
		return static::_config($key, $config);
	}

/**
 * Set one or more connection aliases.
 *
 * Connection aliases allow you to rename active connections without overwriting
 * the aliased connection. This is most useful in the testsuite for replacing
 * connections with their test variant.
 *
 * Defined aliases will take precedence over normal connection names. For example,
 * if you alias 'default' to 'test', fetching 'default' will always return the 'test'
 * connection as long as the alias is defined.
 *
 * You can remove aliases with ConnectionManager::dropAlias().
 *
 * @param string $from The connection to add an alias to.
 * @param string $to The alias to create. $from should return when loaded with get().
 * @return void
 * @throws \Cake\Datasource\Error\MissingDatasourceConfigException When aliasing a
 * connection that does not exist.
 */
	public static function alias($from, $to) {
		if (empty(static::$_config[$to]) && empty(static::$_config[$from])) {
			throw new MissingDatasourceConfigException(
				sprintf('Cannot create alias of "%s" as it does not exist.', $from)
			);
		}
		static::$_aliasMap[$to] = $from;
	}

/**
 * Drop an alias.
 *
 * Removes an alias from ConnectionManager. Fetching the aliased
 * connection may fail if there is no other connection with that name.
 *
 * @param string $name The connection name to remove aliases for.
 * @return void
 */
	public static function dropAlias($name) {
		unset(static::$_aliasMap[$name]);
	}

/**
 * Get a connection.
 *
 * If the connection has not been constructed an instance will be added
 * to the registry. This method will use any aliases that have been
 * defined. If you want the original unaliased connections use getOriginal()
 *
 * @param string $name The connection name.
 * @param bool $useAliases Set to false to not use aliased connections.
 * @return \Cake\Database\Connection A connection object.
 * @throws \Cake\Datasource\Error\MissingDatasourceConfigException When config
 * data is missing.
 */
	public static function get($name, $useAliases = true) {
		if ($useAliases && isset(static::$_aliasMap[$name])) {
			$name = static::$_aliasMap[$name];
		}
		if (empty(static::$_config[$name])) {
			throw new Error\MissingDatasourceConfigException(['name' => $name]);
		}
		if (empty(static::$_registry)) {
			static::$_registry = new ConnectionRegistry();
		}
		if (isset(static::$_registry->{$name})) {
			return static::$_registry->{$name};
		}
		return static::$_registry->load($name, static::$_config[$name]);
	}

}