Duplicate code is one of the most pungent code smells. A rule that is often used is to re-structure code once it is duplicated in three or more places.
Common duplication problems, and corresponding solutions are:
Complex classes like DoctrineCollectionDataSource 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 DoctrineCollectionDataSource, and based on these observations, apply Extract Interface, too.
| 1 | <?php |
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| 18 | final class DoctrineCollectionDataSource extends FilterableDataSource implements IDataSource |
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| 19 | { |
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| 20 | |||
| 21 | /** |
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| 22 | * @var Collection |
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| 23 | */ |
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| 24 | private $data_source; |
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| 25 | |||
| 26 | /** |
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| 27 | * @var string |
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| 28 | */ |
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| 29 | private $primary_key; |
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| 30 | |||
| 31 | /** |
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| 32 | * @var Criteria |
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| 33 | */ |
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| 34 | private $criteria; |
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| 35 | |||
| 36 | /** |
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| 37 | * @var array |
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| 38 | */ |
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| 39 | protected $aggregations = []; |
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| 40 | |||
| 41 | /** |
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| 42 | * @param Collection $collection |
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| 43 | * @param string $primary_key |
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| 44 | */ |
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| 45 | public function __construct(Collection $collection, $primary_key) |
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| 51 | |||
| 52 | |||
| 53 | /** |
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| 54 | * @return Collection |
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| 55 | */ |
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| 56 | private function getFilteredCollection() |
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| 60 | |||
| 61 | |||
| 62 | /******************************************************************************** |
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| 63 | * IDataSource implementation * |
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| 64 | ********************************************************************************/ |
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| 65 | |||
| 66 | |||
| 67 | /** |
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| 68 | * Get count of data |
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| 69 | * @return int |
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| 70 | */ |
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| 71 | public function getCount() |
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| 75 | |||
| 76 | |||
| 77 | /** |
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| 78 | * Get the data |
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| 79 | * @return array |
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| 80 | */ |
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| 81 | public function getData() |
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| 85 | |||
| 86 | |||
| 87 | /** |
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| 88 | * Filter data - get one row |
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| 89 | * @param array $condition |
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| 90 | * @return static |
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| 91 | */ |
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| 92 | public function filterOne(array $condition) |
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| 101 | |||
| 102 | |||
| 103 | /** |
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| 104 | * Filter by date |
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| 105 | * @param Filter\FilterDate $filter |
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| 106 | * @return void |
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| 107 | */ |
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| 108 | public function applyFilterDate(Filter\FilterDate $filter) |
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| 119 | |||
| 120 | |||
| 121 | /** |
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| 122 | * Filter by date range |
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| 123 | * @param Filter\FilterDateRange $filter |
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| 124 | * @return void |
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| 125 | */ |
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| 126 | public function applyFilterDateRange(Filter\FilterDateRange $filter) |
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| 146 | |||
| 147 | |||
| 148 | /** |
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| 149 | * Filter by range |
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| 150 | * @param Filter\FilterRange $filter |
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| 151 | * @return void |
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| 152 | */ |
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| 153 | public function applyFilterRange(Filter\FilterRange $filter) |
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| 167 | |||
| 168 | |||
| 169 | /** |
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| 170 | * Filter by keyword |
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| 171 | * @param Filter\FilterText $filter |
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| 172 | * @return void |
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| 173 | */ |
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| 174 | public function applyFilterText(Filter\FilterText $filter) |
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| 198 | |||
| 199 | |||
| 200 | /** |
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| 201 | * Filter by multi select value |
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| 202 | * @param Filter\FilterMultiSelect $filter |
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| 203 | * @return void |
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| 204 | */ |
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| 205 | public function applyFilterMultiSelect(Filter\FilterMultiSelect $filter) |
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| 212 | |||
| 213 | |||
| 214 | /** |
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| 215 | * Filter by select value |
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| 216 | * @param Filter\FilterSelect $filter |
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| 217 | * @return void |
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| 218 | */ |
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| 219 | public function applyFilterSelect(Filter\FilterSelect $filter) |
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| 226 | |||
| 227 | |||
| 228 | /** |
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| 229 | * Apply limit and offset on data |
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| 230 | * @param int $offset |
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| 231 | * @param int $limit |
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| 232 | * @return static |
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| 233 | */ |
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| 234 | public function limit($offset, $limit) |
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| 240 | |||
| 241 | |||
| 242 | /** |
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| 243 | * Sort data |
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| 244 | * @param Sorting $sorting |
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| 245 | * @return static |
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| 246 | */ |
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| 247 | public function sort(Sorting $sorting) |
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| 268 | |||
| 269 | /** |
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| 270 | * @param string $aggregation_type |
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| 271 | * @param string $column |
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| 272 | * @return mixed |
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| 273 | */ |
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| 274 | public function addAggregationColumn($aggregation_type, $column) |
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| 278 | |||
| 279 | /** |
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| 280 | * get aggregation row |
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| 281 | * @return array |
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| 282 | */ |
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| 283 | View Code Duplication | public function getAggregationData() |
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| 317 | } |
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| 318 |
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: