Complex classes like Serializer 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 Serializer, and based on these observations, apply Extract Interface, too.
| 1 | <?php |
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| 18 | class Serializer extends Component |
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| 19 | { |
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| 20 | /** |
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| 21 | * @var string the name of the query parameter containing the information about which fields should be returned |
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| 22 | * for a [[Model]] object. If the parameter is not provided or empty, the default set of fields as defined |
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| 23 | * by [[Model::fields()]] will be returned. |
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| 24 | */ |
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| 25 | public $fieldsParam = 'fields'; |
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| 26 | /** |
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| 27 | * @var string the name of the query parameter containing the information about which fields should be returned |
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| 28 | * in addition to those listed in [[fieldsParam]] for a resource object. |
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| 29 | */ |
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| 30 | public $expandParam = 'include'; |
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| 31 | /** |
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| 32 | * @var string the name of the envelope (e.g. `_links`) for returning the links objects. |
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| 33 | * It takes effect only, if `collectionEnvelope` is set. |
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| 34 | * @since 2.0.4 |
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| 35 | */ |
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| 36 | public $linksEnvelope = 'links'; |
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| 37 | /** |
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| 38 | * @var string the name of the envelope (e.g. `_meta`) for returning the pagination object. |
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| 39 | * It takes effect only, if `collectionEnvelope` is set. |
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| 40 | * @since 2.0.4 |
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| 41 | */ |
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| 42 | public $metaEnvelope = 'meta'; |
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| 43 | /** |
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| 44 | * @var Request the current request. If not set, the `request` application component will be used. |
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| 45 | */ |
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| 46 | public $request; |
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| 47 | /** |
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| 48 | * @var Response the response to be sent. If not set, the `response` application component will be used. |
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| 49 | */ |
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| 50 | public $response; |
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| 51 | /** |
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| 52 | * @var bool whether to automatically pluralize the `type` of resource. |
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| 53 | */ |
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| 54 | public $pluralize = true; |
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| 55 | |||
| 56 | /** |
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| 57 | * Prepares the member name that should be returned. |
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| 58 | * If not set, all member names will be converted to recommended format. |
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| 59 | * For example, both 'firstName' and 'first_name' will be converted to 'first-name'. |
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| 60 | * @var callable |
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| 61 | */ |
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| 62 | public $prepareMemberName = ['tuyakhov\jsonapi\Inflector', 'var2member']; |
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| 63 | |||
| 64 | /** |
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| 65 | * Converts a member name to an attribute name. |
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| 66 | * @var callable |
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| 67 | */ |
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| 68 | public $formatMemberName = ['tuyakhov\jsonapi\Inflector', 'member2var']; |
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| 69 | |||
| 70 | |||
| 71 | /** |
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| 72 | * @inheritdoc |
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| 73 | */ |
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| 74 | public function init() |
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| 83 | |||
| 84 | /** |
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| 85 | * Serializes the given data into a format that can be easily turned into other formats. |
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| 86 | * This method mainly converts the objects of recognized types into array representation. |
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| 87 | * It will not do conversion for unknown object types or non-object data. |
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| 88 | * @param mixed $data the data to be serialized. |
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| 89 | * @return mixed the converted data. |
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| 90 | */ |
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| 91 | public function serialize($data) |
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| 103 | |||
| 104 | /** |
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| 105 | * @param ResourceInterface $model |
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| 106 | * @return array |
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| 107 | */ |
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| 108 | protected function serializeModel(ResourceInterface $model) |
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| 157 | |||
| 158 | /** |
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| 159 | * @param ResourceInterface $resource |
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| 160 | * @return array |
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| 161 | */ |
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| 162 | protected function serializeResource(ResourceInterface $resource) |
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| 177 | |||
| 178 | /** |
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| 179 | * Serialize resource identifier object and make type juggling |
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| 180 | * @link http://jsonapi.org/format/#document-resource-object-identification |
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| 181 | * @param ResourceIdentifierInterface $identifier |
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| 182 | * @return array |
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| 183 | */ |
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| 184 | protected function serializeIdentifier(ResourceIdentifierInterface $identifier) |
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| 200 | |||
| 201 | /** |
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| 202 | * @param ResourceInterface $resource |
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| 203 | * @param array $includedObjects All included objects from previous serialization, prevent duplicate includes |
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| 204 | * @return array |
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| 205 | */ |
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| 206 | protected function serializeIncluded($resource, $includedObjects = []) |
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| 207 | { |
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| 208 | $included = $this->getIncluded(); |
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| 209 | $relationships = $resource->getResourceRelationships(); |
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| 210 | foreach ($relationships as $name => $relationship) { |
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| 211 | if (!in_array($name, $included)) { |
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| 212 | continue; |
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| 213 | } |
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| 214 | if (!is_array($relationship)) { |
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| 215 | $relationship = [$relationship]; |
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| 216 | } |
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| 217 | foreach ($relationship as $model) { |
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| 218 | if ($model instanceof ResourceInterface) { |
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| 219 | $deduplicateKey = $model->getType() . '|' . $model->getId(); |
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| 220 | if (!isset($includedObjects[$deduplicateKey])) { |
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| 221 | $includedObjects[$deduplicateKey] = $this->serializeModel($model); |
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| 222 | } |
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| 223 | } |
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| 224 | } |
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| 225 | } |
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| 226 | return $includedObjects; |
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| 227 | } |
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| 228 | |||
| 229 | /** |
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| 230 | * Serializes a data provider. |
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| 231 | * @param DataProviderInterface $dataProvider |
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| 232 | * @return array the array representation of the data provider. |
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| 233 | */ |
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| 234 | protected function serializeDataProvider($dataProvider) |
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| 235 | { |
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| 236 | if ($this->request->getIsHead()) { |
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| 237 | return null; |
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| 238 | } else { |
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| 239 | $models = []; |
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| 240 | $includedModels = []; |
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| 241 | |||
| 242 | foreach ($dataProvider->getModels() as $model) { |
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| 243 | if ($model instanceof ResourceInterface) { |
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| 244 | $models[] = $this->serializeModel($model); |
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| 245 | |||
| 246 | $includedModels = $this->serializeIncluded($model, $includedModels); |
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| 247 | } |
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| 248 | } |
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| 249 | |||
| 250 | $result = ['data' => $models]; |
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| 251 | |||
| 252 | if (!empty($includedModels)) { |
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| 253 | $result['included'] = array_values($includedModels); |
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| 254 | } |
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| 255 | |||
| 256 | if (($pagination = $dataProvider->getPagination()) !== false) { |
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| 257 | return array_merge($result, $this->serializePagination($pagination)); |
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| 258 | } |
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| 259 | |||
| 260 | return $result; |
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| 261 | } |
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| 262 | } |
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| 263 | |||
| 264 | /** |
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| 265 | * Serializes a pagination into an array. |
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| 266 | * @param Pagination $pagination |
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| 267 | * @return array the array representation of the pagination |
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| 268 | * @see addPaginationHeaders() |
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| 269 | */ |
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| 270 | protected function serializePagination($pagination) |
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| 282 | |||
| 283 | /** |
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| 284 | * Serializes the validation errors in a model. |
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| 285 | * @param Model $model |
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| 286 | * @return array the array representation of the errors |
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| 287 | */ |
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| 288 | protected function serializeModelErrors($model) |
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| 301 | |||
| 302 | /** |
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| 303 | * @return array |
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| 304 | */ |
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| 305 | protected function getRequestedFields() |
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| 317 | |||
| 318 | protected function getIncluded() |
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| 323 | |||
| 324 | |||
| 325 | /** |
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| 326 | * Format member names according to recommendations for JSON API implementations |
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| 327 | * @link http://jsonapi.org/format/#document-member-names |
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| 328 | * @param array $memberNames |
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| 329 | * @return array |
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| 330 | */ |
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| 331 | protected function prepareMemberNames(array $memberNames = []) |
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| 335 | } |
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| 336 |
This check looks for multiple assignments in successive lines of code. It will report an issue if the operators are not in a straight line.
To visualize
will produce issues in the first and second line, while this second example
will produce no issues.