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 |
||
22 | class Db |
||
23 | { |
||
24 | /** |
||
25 | * Database handle/connection. |
||
26 | * |
||
27 | * @var PDO |
||
28 | */ |
||
29 | protected $pdo; |
||
30 | |||
31 | /** |
||
32 | * @var string |
||
33 | */ |
||
34 | protected $dsn; |
||
35 | |||
36 | /** |
||
37 | * @var string |
||
38 | */ |
||
39 | protected $username; |
||
40 | |||
41 | /** |
||
42 | * @var string |
||
43 | */ |
||
44 | protected $password; |
||
45 | |||
46 | /** |
||
47 | * @var array |
||
48 | */ |
||
49 | protected $options; |
||
50 | |||
51 | /** |
||
52 | * @var bool |
||
53 | */ |
||
54 | protected $hasActiveTransaction = false; |
||
55 | |||
56 | /** |
||
57 | * Constructor. |
||
58 | * |
||
59 | * @param string|PDO $hostDsnOrPdo A MySQL host, a dsn or an existing PDO instance. |
||
60 | * @param string|null $username |
||
61 | * @param string|null $password |
||
62 | * @param string|null $database |
||
63 | * @param array $options |
||
64 | */ |
||
65 | 19 | public function __construct( |
|
84 | |||
85 | /** |
||
86 | */ |
||
87 | 13 | public function connect() |
|
125 | |||
126 | /** |
||
127 | * @param PDOException $exception |
||
128 | * @return bool |
||
129 | */ |
||
130 | private function isConnectionExceptionCausedByConnection(PDOException $exception) |
||
139 | |||
140 | /** |
||
141 | * Close the database connection. |
||
142 | */ |
||
143 | 1 | public function disconnect() |
|
147 | |||
148 | /** |
||
149 | */ |
||
150 | 1 | public function reconnect() |
|
155 | |||
156 | /** |
||
157 | * Check if database connection is open. |
||
158 | * |
||
159 | * @return bool |
||
160 | */ |
||
161 | 14 | public function isConnected() |
|
165 | |||
166 | /** |
||
167 | * Returns the PDO handle. |
||
168 | * |
||
169 | * Can be used to gain access to any special PDO methods. |
||
170 | * |
||
171 | * @return PDO |
||
172 | */ |
||
173 | 2 | public function getPdo() |
|
177 | |||
178 | /** |
||
179 | * Creates and executes a PDO statement. |
||
180 | * |
||
181 | * @param string $sql |
||
182 | * @param array $parameters |
||
183 | * @return PDOStatement |
||
184 | */ |
||
185 | 5 | protected function executeQuery($sql, array $parameters = []) |
|
198 | |||
199 | /** |
||
200 | * Execute an SQL statement and return the number of affected rows. |
||
201 | * |
||
202 | * @param string $sql |
||
203 | * @param array $parameters |
||
204 | * @return int The number of rows affected |
||
205 | */ |
||
206 | 2 | public function exec($sql, array $parameters = []) |
|
212 | |||
213 | /** |
||
214 | * Execute an SQL statement and return the first row. |
||
215 | * |
||
216 | * @param string $sql |
||
217 | * @param array $parameters |
||
218 | * @param bool $indexedKeys |
||
219 | * @return array|false |
||
220 | */ |
||
221 | 1 | public function fetchRow($sql, array $parameters = [], $indexedKeys = false) |
|
227 | |||
228 | /** |
||
229 | * Execute an SQL statement and return all rows as an array. |
||
230 | * |
||
231 | * @param string $sql |
||
232 | * @param array $parameters |
||
233 | * @param bool $indexedKeys |
||
234 | * @return array |
||
235 | */ |
||
236 | 1 | public function fetchRows($sql, array $parameters = [], $indexedKeys = false) |
|
242 | |||
243 | /** |
||
244 | * Execute an SQL statement and return the first column of the first row. |
||
245 | * |
||
246 | * @param string $sql |
||
247 | * @param array $parameters |
||
248 | * @return string|false |
||
249 | */ |
||
250 | 1 | public function fetchValue($sql, array $parameters = []) |
|
256 | |||
257 | /** |
||
258 | * Quote a value for a safe use in query (eg. bla'bla -> 'bla''bla'). |
||
259 | * |
||
260 | * @param mixed $value |
||
261 | * @return string |
||
262 | */ |
||
263 | 1 | public function quote($value) |
|
269 | |||
270 | /** |
||
271 | * Get id of the last inserted row. |
||
272 | * |
||
273 | * @return int |
||
274 | */ |
||
275 | 1 | public function getLastInsertId() |
|
281 | |||
282 | /** |
||
283 | * Prepare parameters for database use. |
||
284 | * |
||
285 | * @param array $parameters |
||
286 | * @return array |
||
287 | */ |
||
288 | 4 | protected function prepareParameters(array $parameters = []) |
|
299 | |||
300 | /** |
||
301 | * Begin transaction (turns off autocommit mode). |
||
302 | * |
||
303 | * @param bool $onlyIfNoActiveTransaction |
||
304 | * @return bool |
||
305 | */ |
||
306 | 4 | public function beginTransaction($onlyIfNoActiveTransaction = false) |
|
319 | |||
320 | /** |
||
321 | * Commits current active transaction (restores autocommit mode). |
||
322 | */ |
||
323 | 2 | public function commit() |
|
330 | |||
331 | /** |
||
332 | * Rolls back current active transaction (restores autocommit mode). |
||
333 | */ |
||
334 | 2 | public function rollBack() |
|
341 | |||
342 | /** |
||
343 | * @return bool |
||
344 | */ |
||
345 | 3 | public function hasActiveTransaction() |
|
349 | |||
350 | /** |
||
351 | * @param string $table |
||
352 | * @param array $data |
||
353 | * @return int The number of rows affected |
||
354 | */ |
||
355 | 1 | public function insert($table, array $data) |
|
367 | |||
368 | /** |
||
369 | * @param string $table |
||
370 | * @param array $data |
||
371 | * @param string $whereSql |
||
372 | * @param array $whereParameters |
||
373 | * @return int The number of rows affected |
||
374 | */ |
||
375 | 1 | public function update($table, array $data, $whereSql = '', array $whereParameters = []) |
|
391 | } |
||
392 |