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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| 16 | final class DoctrineCollectionDataSource extends FilterableDataSource implements IDataSource |
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| 17 | { |
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| 18 | |||
| 19 | /** |
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| 20 | * @var Collection |
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| 21 | */ |
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| 22 | private $data_source; |
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| 23 | |||
| 24 | /** |
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| 25 | * @var string |
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| 26 | */ |
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| 27 | private $primary_key; |
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| 28 | |||
| 29 | /** |
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| 30 | * @var Criteria |
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| 31 | */ |
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| 32 | private $criteria; |
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| 33 | |||
| 34 | /** |
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| 35 | * @var array |
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| 36 | */ |
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| 37 | protected $aggregations = []; |
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| 38 | |||
| 39 | /** |
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| 40 | * @param Collection $collection |
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| 41 | * @param string $primary_key |
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| 42 | */ |
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| 43 | public function __construct(Collection $collection, $primary_key) |
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| 49 | |||
| 50 | |||
| 51 | /** |
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| 52 | * @return Collection |
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| 53 | */ |
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| 54 | private function getFilteredCollection() |
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| 58 | |||
| 59 | |||
| 60 | /******************************************************************************** |
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| 61 | * IDataSource implementation * |
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| 62 | ********************************************************************************/ |
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| 63 | |||
| 64 | |||
| 65 | /** |
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| 66 | * Get count of data |
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| 67 | * @return int |
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| 68 | */ |
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| 69 | public function getCount() |
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| 73 | |||
| 74 | |||
| 75 | /** |
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| 76 | * Get the data |
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| 77 | * @return array |
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| 78 | */ |
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| 79 | public function getData() |
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| 83 | |||
| 84 | |||
| 85 | /** |
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| 86 | * Filter data - get one row |
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| 87 | * @param array $condition |
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| 88 | * @return static |
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| 89 | */ |
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| 90 | public function filterOne(array $condition) |
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| 99 | |||
| 100 | |||
| 101 | /** |
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| 102 | * Filter by date |
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| 103 | * @param Filter\FilterDate $filter |
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| 104 | * @return void |
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| 105 | */ |
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| 106 | public function applyFilterDate(Filter\FilterDate $filter) |
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| 118 | |||
| 119 | |||
| 120 | /** |
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| 121 | * Filter by date range |
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| 122 | * @param Filter\FilterDateRange $filter |
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| 123 | * @return void |
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| 124 | */ |
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| 125 | public function applyFilterDateRange(Filter\FilterDateRange $filter) |
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| 147 | |||
| 148 | |||
| 149 | /** |
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| 150 | * Filter by range |
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| 151 | * @param Filter\FilterRange $filter |
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| 152 | * @return void |
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| 153 | */ |
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| 154 | public function applyFilterRange(Filter\FilterRange $filter) |
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| 168 | |||
| 169 | |||
| 170 | /** |
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| 171 | * Filter by keyword |
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| 172 | * @param Filter\FilterText $filter |
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| 173 | * @return void |
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| 174 | */ |
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| 175 | public function applyFilterText(Filter\FilterText $filter) |
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| 199 | |||
| 200 | |||
| 201 | /** |
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| 202 | * Filter by multi select value |
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| 203 | * @param Filter\FilterMultiSelect $filter |
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| 204 | * @return void |
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| 205 | */ |
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| 206 | public function applyFilterMultiSelect(Filter\FilterMultiSelect $filter) |
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| 213 | |||
| 214 | |||
| 215 | /** |
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| 216 | * Filter by select value |
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| 217 | * @param Filter\FilterSelect $filter |
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| 218 | * @return void |
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| 219 | */ |
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| 220 | public function applyFilterSelect(Filter\FilterSelect $filter) |
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| 227 | |||
| 228 | |||
| 229 | /** |
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| 230 | * Apply limit and offset on data |
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| 231 | * @param int $offset |
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| 232 | * @param int $limit |
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| 233 | * @return static |
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| 234 | */ |
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| 235 | public function limit($offset, $limit) |
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| 241 | |||
| 242 | |||
| 243 | /** |
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| 244 | * Sort data |
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| 245 | * @param Sorting $sorting |
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| 246 | * @return static |
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| 247 | */ |
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| 248 | public function sort(Sorting $sorting) |
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| 269 | |||
| 270 | /** |
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| 271 | * @param string $aggregation_type |
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| 272 | * @param string $column |
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| 273 | * @return mixed |
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| 274 | */ |
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| 275 | public function addAggregationColumn($aggregation_type, $column) |
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| 279 | |||
| 280 | /** |
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| 281 | * get aggregation row |
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| 282 | * @return array |
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| 283 | */ |
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| 284 | View Code Duplication | public function getAggregationData() |
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| 318 | } |
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| 319 |
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: