Complex classes like QueryService 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 QueryService, and based on these observations, apply Extract Interface, too.
1 | <?php |
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26 | class QueryService |
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27 | { |
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28 | |||
29 | /** |
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30 | * @var VisitorInterface |
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31 | */ |
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32 | private $visitor; |
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33 | |||
34 | /** |
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35 | * @var Manager |
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36 | */ |
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37 | private $restrictionManager; |
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38 | |||
39 | /** |
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40 | * @var integer |
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41 | */ |
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42 | private $paginationDefaultLimit; |
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43 | |||
44 | /** |
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45 | * @var Request |
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46 | */ |
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47 | private $request; |
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48 | |||
49 | /** |
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50 | * @var Builder |
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51 | */ |
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52 | private $queryBuilder; |
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53 | |||
54 | /** |
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55 | * @var DocumentRepository |
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56 | */ |
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57 | private $repository; |
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58 | |||
59 | /** |
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60 | * @param VisitorInterface $visitor visitor |
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61 | * @param Manager $restrictionManager restriction manager |
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62 | * @param integer $paginationDefaultLimit default pagination limit |
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63 | */ |
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64 | public function __construct( |
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73 | |||
74 | /** |
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75 | * public function that returns an array of records (or just one record if that's requested) |
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76 | * based on the Request passed to it. |
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77 | * sets all necessary stuff on the querybuilder and the request |
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78 | * |
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79 | * @param Request $request request |
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80 | * @param DocumentRepository $repository repository |
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81 | * |
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82 | * @throws \Doctrine\ODM\MongoDB\MongoDBException |
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83 | * |
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84 | * @return array|null|object either array of records or the record |
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85 | * |
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86 | */ |
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87 | public function getWithRequest(Request &$request, DocumentRepository $repository) |
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148 | |||
149 | /** |
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150 | * if a single document has been requested, this returns the document id. if it returns null, |
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151 | * then we return multiple documents |
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152 | * |
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153 | * @return string|null either document id or null |
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154 | */ |
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155 | private function getDocumentId() |
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159 | |||
160 | /** |
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161 | * apply all stuff from the rql query (if any) to the local querybuilder |
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162 | * |
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163 | * @return void |
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164 | */ |
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165 | private function applyRqlQuery() |
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202 | |||
203 | /** |
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204 | * returns the correct rql query for the request, including optional specified restrictions |
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205 | * in the service definition (via restrictionManager) |
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206 | * |
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207 | * @return Query the query |
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208 | */ |
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209 | private function getRqlQuery() |
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240 | |||
241 | /** |
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242 | * Check if collection has search indexes in DB |
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243 | * |
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244 | * @return bool |
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245 | */ |
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246 | private function hasSearchIndex() |
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271 | |||
272 | /** |
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273 | * get the pagination page size |
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274 | * |
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275 | * @return int page size |
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276 | */ |
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277 | private function getPaginationPageSize() |
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293 | |||
294 | /** |
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295 | * gets the pagination skip |
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296 | * |
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297 | * @return int skip |
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298 | */ |
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299 | private function getPaginationSkip() |
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309 | |||
310 | /** |
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311 | * gets the limit node |
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312 | * |
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313 | * @return bool|LimitNode the node or false |
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314 | */ |
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315 | private function getPaginationLimitNode() |
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326 | } |
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327 |
Let’s take a look at an example:
In the above example, the authenticate() method works fine as long as you just pass instances of MyUser. However, if you now also want to pass a different implementation of User which does not have a getDisplayName() method, the code will break.
Available Fixes
Change the type-hint for the parameter:
Add an additional type-check:
Add the method to the interface: