Complex classes like EntityManager 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 EntityManager, and based on these observations, apply Extract Interface, too.
| 1 | <?php  | 
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| 63 | /* final */class EntityManager implements EntityManagerInterface  | 
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| 64 | { | 
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| 65 | /**  | 
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| 66 | * The used Configuration.  | 
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| 67 | *  | 
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| 68 | * @var \Doctrine\ORM\Configuration  | 
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| 69 | */  | 
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| 70 | private $config;  | 
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| 71 | |||
| 72 | /**  | 
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| 73 | * The database connection used by the EntityManager.  | 
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| 74 | *  | 
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| 75 | * @var \Doctrine\DBAL\Connection  | 
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| 76 | */  | 
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| 77 | private $conn;  | 
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| 78 | |||
| 79 | /**  | 
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| 80 | * The metadata factory, used to retrieve the ORM metadata of entity classes.  | 
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| 81 | *  | 
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| 82 | * @var \Doctrine\ORM\Mapping\ClassMetadataFactory  | 
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| 83 | */  | 
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| 84 | private $metadataFactory;  | 
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| 85 | |||
| 86 | /**  | 
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| 87 | * The UnitOfWork used to coordinate object-level transactions.  | 
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| 88 | *  | 
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| 89 | * @var \Doctrine\ORM\UnitOfWork  | 
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| 90 | */  | 
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| 91 | private $unitOfWork;  | 
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| 92 | |||
| 93 | /**  | 
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| 94 | * The event manager that is the central point of the event system.  | 
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| 95 | *  | 
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| 96 | * @var \Doctrine\Common\EventManager  | 
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| 97 | */  | 
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| 98 | private $eventManager;  | 
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| 99 | |||
| 100 | /**  | 
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| 101 | * The proxy factory used to create dynamic proxies.  | 
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| 102 | *  | 
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| 103 | * @var \Doctrine\ORM\Proxy\ProxyFactory  | 
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| 104 | */  | 
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| 105 | private $proxyFactory;  | 
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| 106 | |||
| 107 | /**  | 
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| 108 | * The repository factory used to create dynamic repositories.  | 
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| 109 | *  | 
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| 110 | * @var \Doctrine\ORM\Repository\RepositoryFactory  | 
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| 111 | */  | 
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| 112 | private $repositoryFactory;  | 
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| 113 | |||
| 114 | /**  | 
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| 115 | * The expression builder instance used to generate query expressions.  | 
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| 116 | *  | 
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| 117 | * @var \Doctrine\ORM\Query\Expr  | 
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| 118 | */  | 
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| 119 | private $expressionBuilder;  | 
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| 120 | |||
| 121 | /**  | 
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| 122 | * Whether the EntityManager is closed or not.  | 
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| 123 | *  | 
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| 124 | * @var bool  | 
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| 125 | */  | 
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| 126 | private $closed = false;  | 
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| 127 | |||
| 128 | /**  | 
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| 129 | * Collection of query filters.  | 
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| 130 | *  | 
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| 131 | * @var \Doctrine\ORM\Query\FilterCollection  | 
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| 132 | */  | 
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| 133 | private $filterCollection;  | 
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| 134 | |||
| 135 | /**  | 
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| 136 | * @var \Doctrine\ORM\Cache The second level cache regions API.  | 
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| 137 | */  | 
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| 138 | private $cache;  | 
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| 139 | |||
| 140 | /**  | 
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| 141 | * Creates a new EntityManager that operates on the given database connection  | 
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| 142 | * and uses the given Configuration and EventManager implementations.  | 
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| 143 | *  | 
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| 144 | * @param \Doctrine\DBAL\Connection $conn  | 
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| 145 | * @param \Doctrine\ORM\Configuration $config  | 
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| 146 | * @param \Doctrine\Common\EventManager $eventManager  | 
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| 147 | */  | 
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| 148 | 2324 | protected function __construct(Connection $conn, Configuration $config, EventManager $eventManager)  | 
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| 175 | |||
| 176 | /**  | 
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| 177 |      * {@inheritDoc} | 
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| 178 | */  | 
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| 179 | 1827 | public function getConnection()  | 
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| 183 | |||
| 184 | /**  | 
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| 185 | * Gets the metadata factory used to gather the metadata of classes.  | 
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| 186 | *  | 
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| 187 | * @return \Doctrine\ORM\Mapping\ClassMetadataFactory  | 
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| 188 | */  | 
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| 189 | 2324 | public function getMetadataFactory()  | 
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| 193 | |||
| 194 | /**  | 
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| 195 |      * {@inheritDoc} | 
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| 196 | */  | 
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| 197 | 17 | public function getExpressionBuilder()  | 
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| 205 | |||
| 206 | /**  | 
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| 207 |      * {@inheritDoc} | 
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| 208 | */  | 
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| 209 | 2 | public function beginTransaction()  | 
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| 213 | |||
| 214 | /**  | 
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| 215 |      * {@inheritDoc} | 
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| 216 | */  | 
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| 217 | 210 | public function getCache()  | 
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| 221 | |||
| 222 | /**  | 
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| 223 |      * {@inheritDoc} | 
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| 224 | */  | 
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| 225 | 4 | public function transactional($func)  | 
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| 247 | |||
| 248 | /**  | 
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| 249 |      * {@inheritDoc} | 
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| 250 | */  | 
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| 251 | 1 | public function commit()  | 
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| 255 | |||
| 256 | /**  | 
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| 257 |      * {@inheritDoc} | 
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| 258 | */  | 
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| 259 | 1 | public function rollback()  | 
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| 263 | |||
| 264 | /**  | 
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| 265 | * Returns the ORM metadata descriptor for a class.  | 
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| 266 | *  | 
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| 267 | * The class name must be the fully-qualified class name without a leading backslash  | 
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| 268 | * (as it is returned by get_class($obj)) or an aliased class name.  | 
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| 269 | *  | 
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| 270 | * Examples:  | 
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| 271 | * MyProject\Domain\User  | 
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| 272 | * sales:PriceRequest  | 
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| 273 | *  | 
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| 274 | * Internal note: Performance-sensitive method.  | 
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| 275 | *  | 
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| 276 | * @param string $className  | 
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| 277 | *  | 
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| 278 | * @return \Doctrine\ORM\Mapping\ClassMetadata  | 
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| 279 | */  | 
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| 280 | 1881 | public function getClassMetadata($className)  | 
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| 284 | |||
| 285 | /**  | 
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| 286 |      * {@inheritDoc} | 
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| 287 | */  | 
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| 288 | 921 | public function createQuery($dql = '')  | 
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| 298 | |||
| 299 | /**  | 
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| 300 |      * {@inheritDoc} | 
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| 301 | */  | 
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| 302 | 1 | public function createNamedQuery($name)  | 
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| 306 | |||
| 307 | /**  | 
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| 308 |      * {@inheritDoc} | 
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| 309 | */  | 
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| 310 | 21 | public function createNativeQuery($sql, ResultSetMapping $rsm)  | 
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| 319 | |||
| 320 | /**  | 
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| 321 |      * {@inheritDoc} | 
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| 322 | */  | 
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| 323 | 1 | public function createNamedNativeQuery($name)  | 
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| 329 | |||
| 330 | /**  | 
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| 331 |      * {@inheritDoc} | 
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| 332 | */  | 
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| 333 | 112 | public function createQueryBuilder()  | 
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| 337 | |||
| 338 | /**  | 
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| 339 | * Flushes all changes to objects that have been queued up to now to the database.  | 
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| 340 | * This effectively synchronizes the in-memory state of managed objects with the  | 
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| 341 | * database.  | 
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| 342 | *  | 
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| 343 | * If an entity is explicitly passed to this method only this entity and  | 
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| 344 | * the cascade-persist semantics + scheduled inserts/removals are synchronized.  | 
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| 345 | *  | 
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| 346 | * @param null|object|array $entity  | 
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| 347 | *  | 
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| 348 | * @return void  | 
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| 349 | *  | 
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| 350 | * @throws \Doctrine\ORM\OptimisticLockException If a version check on an entity that  | 
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| 351 | * makes use of optimistic locking fails.  | 
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| 352 | * @throws ORMException  | 
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| 353 | */  | 
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| 354 | 1009 | public function flush($entity = null)  | 
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| 360 | |||
| 361 | /**  | 
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| 362 | * Finds an Entity by its identifier.  | 
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| 363 | *  | 
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| 364 | * @param string $entityName The class name of the entity to find.  | 
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| 365 | * @param mixed $id The identity of the entity to find.  | 
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| 366 | * @param integer|null $lockMode One of the \Doctrine\DBAL\LockMode::* constants  | 
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| 367 | * or NULL if no specific lock mode should be used  | 
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| 368 | * during the search.  | 
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| 369 | * @param integer|null $lockVersion The version of the entity to find when using  | 
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| 370 | * optimistic locking.  | 
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| 371 | *  | 
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| 372 | * @return object|null The entity instance or NULL if the entity can not be found.  | 
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| 373 | *  | 
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| 374 | * @throws OptimisticLockException  | 
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| 375 | * @throws ORMInvalidArgumentException  | 
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| 376 | * @throws TransactionRequiredException  | 
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| 377 | * @throws ORMException  | 
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| 378 | */  | 
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| 379 | 409 | public function find($entityName, $id, $lockMode = null, $lockVersion = null)  | 
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| 466 | |||
| 467 | /**  | 
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| 468 |      * {@inheritDoc} | 
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| 469 | */  | 
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| 470 | 90 | public function getReference($entityName, $id)  | 
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| 508 | |||
| 509 | /**  | 
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| 510 |      * {@inheritDoc} | 
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| 511 | */  | 
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| 512 | 4 | public function getPartialReference($entityName, $identifier)  | 
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| 534 | |||
| 535 | /**  | 
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| 536 | * Clears the EntityManager. All entities that are currently managed  | 
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| 537 | * by this EntityManager become detached.  | 
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| 538 | *  | 
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| 539 | * @param string|null $entityName if given, only entities of this type will get detached  | 
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| 540 | *  | 
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| 541 | * @return void  | 
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| 542 | */  | 
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| 543 | 1215 | public function clear($entityName = null)  | 
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| 547 | |||
| 548 | /**  | 
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| 549 |      * {@inheritDoc} | 
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| 550 | */  | 
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| 551 | 19 | public function close()  | 
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| 557 | |||
| 558 | /**  | 
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| 559 | * Tells the EntityManager to make an instance managed and persistent.  | 
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| 560 | *  | 
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| 561 | * The entity will be entered into the database at or before transaction  | 
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| 562 | * commit or as a result of the flush operation.  | 
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| 563 | *  | 
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| 564 | * NOTE: The persist operation always considers entities that are not yet known to  | 
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| 565 | * this EntityManager as NEW. Do not pass detached entities to the persist operation.  | 
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| 566 | *  | 
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| 567 | * @param object $entity The instance to make managed and persistent.  | 
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| 568 | *  | 
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| 569 | * @return void  | 
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| 570 | *  | 
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| 571 | * @throws ORMInvalidArgumentException  | 
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| 572 | * @throws ORMException  | 
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| 573 | */  | 
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| 574 | 1003 | public function persist($entity)  | 
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| 584 | |||
| 585 | /**  | 
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| 586 | * Removes an entity instance.  | 
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| 587 | *  | 
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| 588 | * A removed entity will be removed from the database at or before transaction commit  | 
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| 589 | * or as a result of the flush operation.  | 
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| 590 | *  | 
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| 591 | * @param object $entity The entity instance to remove.  | 
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| 592 | *  | 
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| 593 | * @return void  | 
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| 594 | *  | 
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| 595 | * @throws ORMInvalidArgumentException  | 
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| 596 | * @throws ORMException  | 
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| 597 | */  | 
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| 598 | 50 | public function remove($entity)  | 
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| 608 | |||
| 609 | /**  | 
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| 610 | * Refreshes the persistent state of an entity from the database,  | 
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| 611 | * overriding any local changes that have not yet been persisted.  | 
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| 612 | *  | 
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| 613 | * @param object $entity The entity to refresh.  | 
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| 614 | *  | 
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| 615 | * @return void  | 
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| 616 | *  | 
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| 617 | * @throws ORMInvalidArgumentException  | 
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| 618 | * @throws ORMException  | 
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| 619 | */  | 
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| 620 | 18 | public function refresh($entity)  | 
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| 630 | |||
| 631 | /**  | 
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| 632 | * Detaches an entity from the EntityManager, causing a managed entity to  | 
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| 633 | * become detached. Unflushed changes made to the entity if any  | 
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| 634 | * (including removal of the entity), will not be synchronized to the database.  | 
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| 635 | * Entities which previously referenced the detached entity will continue to  | 
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| 636 | * reference it.  | 
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| 637 | *  | 
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| 638 | * @param object $entity The entity to detach.  | 
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| 639 | *  | 
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| 640 | * @return void  | 
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| 641 | *  | 
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| 642 | * @throws ORMInvalidArgumentException  | 
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| 643 | */  | 
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| 644 | 13 | public function detach($entity)  | 
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| 652 | |||
| 653 | /**  | 
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| 654 | * Merges the state of a detached entity into the persistence context  | 
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| 655 | * of this EntityManager and returns the managed copy of the entity.  | 
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| 656 | * The entity passed to merge will not become associated/managed with this EntityManager.  | 
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| 657 | *  | 
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| 658 | * @param object $entity The detached entity to merge into the persistence context.  | 
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| 659 | *  | 
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| 660 | * @return object The managed copy of the entity.  | 
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| 661 | *  | 
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| 662 | * @throws ORMInvalidArgumentException  | 
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| 663 | * @throws ORMException  | 
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| 664 | */  | 
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| 665 | 42 | public function merge($entity)  | 
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| 675 | |||
| 676 | /**  | 
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| 677 |      * {@inheritDoc} | 
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| 678 | *  | 
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| 679 | * @todo Implementation need. This is necessary since $e2 = clone $e1; throws an E_FATAL when access anything on $e:  | 
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| 680 | * Fatal error: Maximum function nesting level of '100' reached, aborting!  | 
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| 681 | */  | 
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| 682 | public function copy($entity, $deep = false)  | 
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| 686 | |||
| 687 | /**  | 
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| 688 |      * {@inheritDoc} | 
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| 689 | */  | 
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| 690 | 10 | public function lock($entity, $lockMode, $lockVersion = null)  | 
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| 694 | |||
| 695 | /**  | 
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| 696 | * Gets the repository for an entity class.  | 
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| 697 | *  | 
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| 698 | * @param string $entityName The name of the entity.  | 
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| 699 | *  | 
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| 700 | * @return \Doctrine\ORM\EntityRepository The repository class.  | 
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| 701 | */  | 
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| 702 | 144 | public function getRepository($entityName)  | 
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| 706 | |||
| 707 | /**  | 
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| 708 | * Determines whether an entity instance is managed in this EntityManager.  | 
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| 709 | *  | 
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| 710 | * @param object $entity  | 
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| 711 | *  | 
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| 712 | * @return boolean TRUE if this EntityManager currently manages the given entity, FALSE otherwise.  | 
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| 713 | */  | 
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| 714 | 22 | public function contains($entity)  | 
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| 720 | |||
| 721 | /**  | 
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| 722 |      * {@inheritDoc} | 
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| 723 | */  | 
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| 724 | 2324 | public function getEventManager()  | 
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| 728 | |||
| 729 | /**  | 
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| 730 |      * {@inheritDoc} | 
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| 731 | */  | 
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| 732 | 2324 | public function getConfiguration()  | 
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| 736 | |||
| 737 | /**  | 
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| 738 | * Throws an exception if the EntityManager is closed or currently not active.  | 
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| 739 | *  | 
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| 740 | * @return void  | 
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| 741 | *  | 
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| 742 | * @throws ORMException If the EntityManager is closed.  | 
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| 743 | */  | 
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| 744 | 1022 | private function errorIfClosed()  | 
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| 750 | |||
| 751 | /**  | 
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| 752 |      * {@inheritDoc} | 
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| 753 | */  | 
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| 754 | 1 | public function isOpen()  | 
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| 758 | |||
| 759 | /**  | 
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| 760 |      * {@inheritDoc} | 
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| 761 | */  | 
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| 762 | 2324 | public function getUnitOfWork()  | 
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| 766 | |||
| 767 | /**  | 
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| 768 |      * {@inheritDoc} | 
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| 769 | */  | 
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| 770 | public function getHydrator($hydrationMode)  | 
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| 774 | |||
| 775 | /**  | 
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| 776 |      * {@inheritDoc} | 
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| 777 | */  | 
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| 778 | 889 | public function newHydrator($hydrationMode)  | 
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| 804 | |||
| 805 | /**  | 
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| 806 |      * {@inheritDoc} | 
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| 807 | */  | 
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| 808 | 165 | public function getProxyFactory()  | 
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| 812 | |||
| 813 | /**  | 
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| 814 |      * {@inheritDoc} | 
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| 815 | */  | 
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| 816 | public function initializeObject($obj)  | 
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| 820 | |||
| 821 | /**  | 
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| 822 | * Factory method to create EntityManager instances.  | 
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| 823 | *  | 
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| 824 | * @param mixed $conn An array with the connection parameters or an existing Connection instance.  | 
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| 825 | * @param Configuration $config The Configuration instance to use.  | 
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| 826 | * @param EventManager $eventManager The EventManager instance to use.  | 
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| 827 | *  | 
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| 828 | * @return EntityManager The created EntityManager.  | 
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| 829 | *  | 
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| 830 | * @throws \InvalidArgumentException  | 
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| 831 | * @throws ORMException  | 
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| 832 | */  | 
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| 833 | 1227 | public static function create($conn, Configuration $config, EventManager $eventManager = null)  | 
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| 843 | |||
| 844 | /**  | 
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| 845 | * Factory method to create Connection instances.  | 
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| 846 | *  | 
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| 847 | * @param mixed $conn An array with the connection parameters or an existing Connection instance.  | 
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| 848 | * @param Configuration $config The Configuration instance to use.  | 
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| 849 | * @param EventManager $eventManager The EventManager instance to use.  | 
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| 850 | *  | 
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| 851 | * @return Connection  | 
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| 852 | *  | 
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| 853 | * @throws ORMException  | 
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| 854 | * @throws \Doctrine\DBAL\DBALException  | 
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| 855 | */  | 
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| 856 | 1227 | protected static function createConnection($conn, Configuration $config, EventManager $eventManager = null)  | 
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| 872 | |||
| 873 | /**  | 
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| 874 |      * {@inheritDoc} | 
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| 875 | */  | 
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| 876 | 613 | public function getFilters()  | 
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| 884 | |||
| 885 | /**  | 
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| 886 |      * {@inheritDoc} | 
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| 887 | */  | 
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| 888 | 35 | public function isFiltersStateClean()  | 
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| 892 | |||
| 893 | /**  | 
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| 894 |      * {@inheritDoc} | 
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| 895 | */  | 
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| 896 | 732 | public function hasFilters()  | 
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| 900 | }  | 
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| 901 | 
If you access a property on an interface, you most likely code against a concrete implementation of the interface.
Available Fixes
Adding an additional type check:
Changing the type hint: