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 | * Constructor. |
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58 | * |
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59 | * @param string|PDO $hostDsnOrPdo A MySQL host, a dsn or an existing PDO instance. |
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60 | * @param string|null $username |
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61 | * @param string|null $password |
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62 | * @param string|null $database |
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63 | * @param array $options |
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64 | */ |
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65 | 18 | public function __construct( |
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84 | |||
85 | /** |
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86 | */ |
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87 | 13 | public function connect() |
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125 | |||
126 | /** |
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127 | * @param PDOException $exception |
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128 | * @return bool |
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129 | */ |
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130 | private function isConnectionExceptionCausedByConnection(PDOException $exception) |
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138 | |||
139 | /** |
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140 | * Close database connection. |
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141 | */ |
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142 | 1 | public function disconnect() |
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146 | |||
147 | /** |
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148 | * Check if database connection is open. |
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149 | * |
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150 | * @return bool |
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151 | */ |
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152 | 14 | public function isConnected() |
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156 | |||
157 | /** |
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158 | * Returns the PDO handle. |
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159 | * |
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160 | * Can be used to gain access to any special PDO methods. |
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161 | * |
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162 | * @return PDO |
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163 | */ |
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164 | 2 | public function getPdo() |
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168 | |||
169 | /** |
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170 | * Creates and executes a PDO statement. |
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171 | * |
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172 | * @param string $sql |
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173 | * @param array $parameters |
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174 | * @return PDOStatement |
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175 | */ |
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176 | 5 | protected function executeQuery($sql, array $parameters = []) |
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189 | |||
190 | /** |
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191 | * Execute an SQL statement and return the number of affected rows. |
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192 | * |
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193 | * @param string $sql |
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194 | * @param array $parameters |
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195 | * @return int The number of rows affected |
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196 | */ |
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197 | 2 | public function exec($sql, array $parameters = []) |
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203 | |||
204 | /** |
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205 | * Execute an SQL statement and return the first row. |
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206 | * |
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207 | * @param string $sql |
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208 | * @param array $parameters |
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209 | * @param bool $indexedKeys |
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210 | * @return array|false |
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211 | */ |
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212 | 1 | public function fetchRow($sql, array $parameters = [], $indexedKeys = false) |
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218 | |||
219 | /** |
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220 | * Execute an SQL statement and return all rows as an array. |
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221 | * |
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222 | * @param string $sql |
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223 | * @param array $parameters |
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224 | * @param bool $indexedKeys |
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225 | * @return array |
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226 | */ |
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227 | 1 | public function fetchAll($sql, array $parameters = [], $indexedKeys = false) |
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233 | |||
234 | /** |
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235 | * Execute an SQL statement and return the first column of the first row. |
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236 | * |
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237 | * @param string $sql |
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238 | * @param array $parameters |
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239 | * @return string|false |
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240 | */ |
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241 | 1 | public function fetchOne($sql, array $parameters = []) |
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247 | |||
248 | /** |
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249 | * Quote a value for a safe use in query (eg. bla'bla -> 'bla''bla'). |
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250 | * |
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251 | * @param mixed $value |
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252 | * @return string |
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253 | */ |
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254 | 1 | public function quote($value) |
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260 | |||
261 | /** |
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262 | * Get id of the last inserted row. |
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263 | * |
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264 | * @return int |
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265 | */ |
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266 | 1 | public function getLastInsertId() |
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272 | |||
273 | /** |
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274 | * Prepare parameters for database use. |
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275 | * |
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276 | * @param array $parameters |
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277 | * @return array |
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278 | */ |
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279 | 4 | protected function prepareParameters(array $parameters = []) |
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290 | |||
291 | /** |
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292 | * Begin transaction (turns off autocommit mode). |
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293 | * |
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294 | * @param bool $onlyIfNoActiveTransaction |
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295 | * @return bool |
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296 | */ |
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297 | 4 | public function beginTransaction($onlyIfNoActiveTransaction = false) |
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310 | |||
311 | /** |
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312 | * Commits current active transaction (restores autocommit mode). |
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313 | */ |
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314 | 2 | public function commit() |
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321 | |||
322 | /** |
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323 | * Rolls back current active transaction (restores autocommit mode). |
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324 | */ |
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325 | 2 | public function rollBack() |
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332 | |||
333 | /** |
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334 | * @return bool |
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335 | */ |
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336 | 3 | public function hasActiveTransaction() |
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340 | |||
341 | /** |
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342 | * @param string $table |
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343 | * @param array $data |
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344 | * @return int The number of rows affected |
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345 | */ |
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346 | 1 | public function insert($table, array $data) |
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358 | |||
359 | /** |
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360 | * @param string $table |
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361 | * @param array $data |
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362 | * @param string $whereSql |
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363 | * @param array $whereParameters |
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364 | * @return int The number of rows affected |
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365 | */ |
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366 | 1 | public function update($table, array $data, $whereSql = '', array $whereParameters = []) |
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382 | } |
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383 |