1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
|
<?php
# Lifter010: TODO
/*
* Copyright (C) 2007 - Marcus Lunzenauer <mlunzena@uos.de>
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License as
* published by the Free Software Foundation; either version 2 of
* the License, or (at your option) any later version.
*/
/**
* This class provides a singleton instance that is used to manage PDO database
* connections.
*
* Example of use:
* @code
* # get hold of the DBManager's singleton
* $manager = DBManager::getInstance();
*
* # set PDO connections using a DSN
* $manager->setConnection('example',
* 'mysql:host=localhost;dbname=example',
* 'root', '');
* # or an existing instance of PDO
* $manager->setConnection('example2', $existingPdo);
*
* # retrieve a PDO connection later in your code
* $db = $manager->getConnection("studip");
*
* # or as a shortcut
* $db = DBManager::get("studip");
*
* # or even shorter ("studip" is the default key)
* $db = DBManager::get();
*
* # and use the connection
* $db->query('SELECT * FROM user_info');
*
* # you may even alias connections
* $manager->aliasConnection("studip", "studip-slave");
*
* # but this is just sugar for
* $studip = $manager->getConnection("studip");
* $manager->setConnection("studip-slave", $studip);
*
* @endcode
*/
class DBManager
{
/**
* the singleton instance
*
* @access private
* @var DBManager
*/
static private $instance;
/**
* an array of connections of the singleton instance
*
* @access private
* @var array
*/
private $connections;
/**
* @access private
*
* @return void
*/
private function __construct()
{
$this->connections = [];
}
/**
* This method returns the singleton instance of this class.
*
* @return DBManager the singleton instance
*/
static public function getInstance()
{
if (is_null(DBManager::$instance)) {
DBManager::$instance = new DBManager();
}
return DBManager::$instance;
}
/**
* This method returns the database connection to the given key. Throws a
* DBManagerException if there is no such connection.
*
* Example usage:
* @code
* try {
* $db = DBManager::getInstance()->getConnection("foo");
* $db->exec($sql);
* } catch (DBManagerException $e) {
* echo "oops";
* }
* @endcode
*
* @param string the key
*
* @throw DBManagerException
*
* @return PDO the database connection
*/
public function getConnection($database)
{
if (!isset($this->connections[$database])) {
throw new DBManagerException('Database connection: "'.$database.
'" does not exist.');
}
return $this->connections[$database];
}
/**
* This method maps the specified key to the specified database connection.
*
* You can either use an instance of class PDO or specify a DSN (optionally
* with username/password).
*
* The (possibly newly created) connection is configured to throw exceptions
* and to buffer queries if it is a MySQL connection.
*
* Examples:
* @code
* $dbManager = DBManager::getInstance();
*
* // using an existing PDO connection
* $existingPdo = new LoggingPDO($dsn);
* $dbManager->setConnection('studip', $pdo);
*
* // using a DSN with username and password
* $dbManager->setConnection('studip', $dsn , $username, $password);
* @endcode
*
* @param string the key
* @param string|PDO either a DSN or an existing PDO connection
* @param string (optional) the connection's username
* @param array (optional) the connection's password
*
* @return DBManager this instance, useful for cascading method calls
*/
public function setConnection($database, $dsnOrConnection, $user = NULL,
$pass = NULL)
{
$connection = $dsnOrConnection instanceof PDO
? $dsnOrConnection
: new StudipPDO($dsnOrConnection, $user, $pass);
$this->configureConnection($connection);
$this->connections[$database] = $connection;
return $this;
}
// PDO connection should throw exceptions and use buffered queries
private function configureConnection($connection)
{
$connection->setAttribute(PDO::ATTR_ERRMODE, PDO::ERRMODE_EXCEPTION);
if ($connection->getAttribute(PDO::ATTR_DRIVER_NAME) == 'mysql') {
$connection->setAttribute(PDO::MYSQL_ATTR_USE_BUFFERED_QUERY, true);
// $connection->exec('SET CHARACTER SET latin1');
}
}
/**
* This method creates an alias for a database connection.
*
* This is useful if you want to use different keys but access the same
* database, e.g. if you want to use master-slave replication in the future
*
* @param string the old key of the database connection
* @param string the new key of the database connection
*
* @return DBManager this instance, useful for cascading method calls
*/
public function aliasConnection($old, $new)
{
if (!isset($this->connections[$old])) {
throw new DBManagerException('No database found using key: ' . $old);
}
$this->connections[$new] = $this->connections[$old];
return $this;
}
/**
* Shortcut static method to retrieve the database connection for a given
* key.
*
* Example usage:
* @code
* // instead of
* $db = DBManager::getInstance()->getConnection("studip");
*
* // this can be shortened to
* $db = DBManager::get("studip");
*
* // or in this case (as "studip" is the default key)
* $db = DBManager::get();
* @endcode
*
* @param string the key
*
* @return StudipPDO the database connection
*/
static public function get($database = 'studip')
{
$manager = DBManager::getInstance();
return $manager->getConnection($database);
}
}
/**
* The DBManager throws this exception if it cannot find a connection using
* a non existant key.
*/
class DBManagerException extends Exception
{
/**
* @param string the message of this exception
*
* @return void
*/
public function __construct($message)
{
parent::__construct($message);
}
}
|
