Complex classes like Db often do a lot of different things. To break such a class down, we need to identify a cohesive component within that class. A common approach to find such a component is to look for fields/methods that share the same prefixes, or suffixes. You can also have a look at the cohesion graph to spot any un-connected, or weakly-connected components.
Once you have determined the fields that belong together, you can apply the Extract Class refactoring. If the component makes sense as a sub-class, Extract Subclass is also a candidate, and is often faster.
While breaking up the class, it is a good idea to analyze how other classes use Db, and based on these observations, apply Extract Interface, too.
| 1 | <?php |
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| 22 | class Db |
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| 23 | { |
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| 24 | /** |
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| 25 | * Database handle/connection. |
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| 26 | * |
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| 27 | * @var PDO |
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| 28 | */ |
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| 29 | protected $pdo; |
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| 30 | |||
| 31 | /** |
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| 32 | * @var string |
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| 33 | */ |
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| 34 | protected $dsn; |
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| 35 | |||
| 36 | /** |
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| 37 | * @var string |
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| 38 | */ |
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| 39 | protected $username; |
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| 40 | |||
| 41 | /** |
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| 42 | * @var string |
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| 43 | */ |
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| 44 | protected $password; |
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| 45 | |||
| 46 | /** |
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| 47 | * @var array |
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| 48 | */ |
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| 49 | protected $options; |
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| 50 | |||
| 51 | /** |
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| 52 | * @var bool |
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| 53 | */ |
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| 54 | protected $hasActiveTransaction = false; |
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| 55 | |||
| 56 | /** |
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| 57 | * @var PdoFactoryInterface |
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| 58 | */ |
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| 59 | private $pdoFactory; |
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| 60 | |||
| 61 | /** |
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| 62 | * Constructor. |
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| 63 | * |
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| 64 | * @param string|PDO $hostDsnOrPdo A MySQL host, a dsn or an existing PDO instance. |
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| 65 | * @param string|null $username |
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| 66 | * @param string|null $password |
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| 67 | * @param string|null $database |
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| 68 | * @param array $options |
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| 69 | * @param PdoFactoryInterface $pdoFactory |
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| 70 | * |
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| 71 | * @deprecated The signature of the constructor will change in version 1.0.0 and accept |
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| 72 | * only a PDO dsn string as first parameter dropping support to inject a PDO instance or host string |
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| 73 | */ |
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| 74 | 28 | public function __construct( |
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| 106 | |||
| 107 | /** |
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| 108 | */ |
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| 109 | 18 | public function connect() |
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| 132 | |||
| 133 | /** |
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| 134 | * @param PDOException $exception |
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| 135 | * @return bool |
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| 136 | */ |
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| 137 | 2 | private function isConnectionExceptionCausedByConnection(PDOException $exception) |
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| 146 | |||
| 147 | /** |
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| 148 | * Close the database connection. |
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| 149 | */ |
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| 150 | 1 | public function disconnect() |
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| 154 | |||
| 155 | /** |
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| 156 | */ |
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| 157 | 1 | public function reconnect() |
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| 162 | |||
| 163 | /** |
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| 164 | * Check if database connection is open. |
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| 165 | * |
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| 166 | * @return bool |
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| 167 | */ |
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| 168 | 19 | public function isConnected() |
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| 172 | |||
| 173 | /** |
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| 174 | * Returns the PDO handle. |
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| 175 | * |
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| 176 | * Can be used to gain access to any special PDO methods. |
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| 177 | * |
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| 178 | * @return PDO |
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| 179 | */ |
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| 180 | 4 | public function getPdo() |
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| 184 | |||
| 185 | /** |
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| 186 | * Creates and executes a PDO statement. |
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| 187 | * |
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| 188 | * @param string $sql |
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| 189 | * @param array $parameters |
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| 190 | * @return PDOStatement |
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| 191 | */ |
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| 192 | 7 | protected function executeQuery($sql, array $parameters = []) |
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| 206 | |||
| 207 | /** |
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| 208 | * Execute an SQL statement and return the number of affected rows. |
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| 209 | * |
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| 210 | * @param string $sql |
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| 211 | * @param array $parameters |
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| 212 | * @return int The number of rows affected |
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| 213 | */ |
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| 214 | 4 | public function exec($sql, array $parameters = []) |
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| 220 | |||
| 221 | /** |
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| 222 | * Execute an SQL statement and return the first row. |
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| 223 | * |
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| 224 | * @param string $sql |
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| 225 | * @param array $parameters |
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| 226 | * @param bool $indexedKeys |
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| 227 | * @return array|false |
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| 228 | */ |
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| 229 | 1 | public function fetchRow($sql, array $parameters = [], $indexedKeys = false) |
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| 235 | |||
| 236 | /** |
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| 237 | * Execute an SQL statement and return all rows as an array. |
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| 238 | * |
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| 239 | * @param string $sql |
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| 240 | * @param array $parameters |
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| 241 | * @param bool $indexedKeys |
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| 242 | * @return array |
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| 243 | */ |
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| 244 | 1 | public function fetchRows($sql, array $parameters = [], $indexedKeys = false) |
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| 250 | |||
| 251 | /** |
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| 252 | * Execute an SQL statement and return the first column of the first row. |
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| 253 | * |
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| 254 | * @param string $sql |
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| 255 | * @param array $parameters |
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| 256 | * @return string|false |
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| 257 | */ |
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| 258 | 1 | public function fetchValue($sql, array $parameters = []) |
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| 264 | |||
| 265 | /** |
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| 266 | * Quote a value for a safe use in query (eg. bla'bla -> 'bla''bla'). |
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| 267 | * |
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| 268 | * @param mixed $value |
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| 269 | * @return string |
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| 270 | */ |
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| 271 | 1 | public function quote($value) |
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| 277 | |||
| 278 | /** |
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| 279 | * Get id of the last inserted row. |
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| 280 | * |
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| 281 | * @return int |
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| 282 | */ |
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| 283 | 1 | public function getLastInsertId() |
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| 289 | |||
| 290 | /** |
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| 291 | * Prepare parameters for database use. |
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| 292 | * |
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| 293 | * @param array $parameters |
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| 294 | * @return array |
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| 295 | */ |
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| 296 | 7 | protected function prepareParameters(array $parameters = []) |
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| 313 | |||
| 314 | /** |
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| 315 | * Begin transaction (turns off autocommit mode). |
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| 316 | * |
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| 317 | * @param bool $onlyIfNoActiveTransaction |
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| 318 | * @return bool |
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| 319 | */ |
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| 320 | 4 | public function beginTransaction($onlyIfNoActiveTransaction = false) |
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| 333 | |||
| 334 | /** |
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| 335 | * Commits current active transaction (restores autocommit mode). |
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| 336 | */ |
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| 337 | 2 | public function commit() |
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| 344 | |||
| 345 | /** |
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| 346 | * Rolls back current active transaction (restores autocommit mode). |
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| 347 | */ |
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| 348 | 2 | public function rollBack() |
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| 355 | |||
| 356 | /** |
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| 357 | * @return bool |
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| 358 | */ |
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| 359 | 3 | public function hasActiveTransaction() |
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| 363 | |||
| 364 | /** |
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| 365 | * @param string $table |
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| 366 | * @param array $data |
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| 367 | * @param bool $updateOnDuplicateKey |
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| 368 | * @return int The number of rows affected |
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| 369 | */ |
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| 370 | 3 | public function insert($table, array $data, $updateOnDuplicateKey = false) |
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| 395 | |||
| 396 | /** |
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| 397 | * @param array $assignmentData |
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| 398 | * @return string |
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| 399 | */ |
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| 400 | 2 | protected function getAssignmentSql(array $assignmentData) |
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| 409 | |||
| 410 | /** |
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| 411 | * @param string $table |
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| 412 | * @param array $data |
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| 413 | * @param string $whereSql |
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| 414 | * @param array $whereParameters |
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| 415 | * @return int The number of rows affected |
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| 416 | */ |
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| 417 | 1 | public function update($table, array $data, $whereSql = '', array $whereParameters = []) |
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| 431 | } |
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| 432 |
If you suppress an error, we recommend checking for the error condition explicitly: