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 MSSQLSchemaManager 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 MSSQLSchemaManager, and based on these observations, apply Extract Interface, too.
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| 15 | class MSSQLSchemaManager extends DBSchemaManager |
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| 16 | { |
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| 17 | |||
| 18 | /** |
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| 19 | * Stores per-request cached constraint checks that come from the database. |
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| 20 | * |
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| 21 | * @var array |
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| 22 | */ |
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| 23 | protected static $cached_checks = array(); |
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| 24 | |||
| 25 | /** |
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| 26 | * Builds the internal MS SQL Server index name given the silverstripe table and index name |
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| 27 | * |
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| 28 | * @param string $tableName |
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| 29 | * @param string $indexName |
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| 30 | * @param string $prefix The optional prefix for the index. Defaults to "ix" for indexes. |
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| 31 | * @return string The name of the index |
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| 32 | */ |
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| 33 | public function buildMSSQLIndexName($tableName, $indexName, $prefix = 'ix') |
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| 42 | |||
| 43 | |||
| 44 | /** |
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| 45 | * This will set up the full text search capabilities. |
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| 46 | * |
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| 47 | * @param string $name Name of full text catalog to use |
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| 48 | */ |
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| 49 | public function createFullTextCatalog($name = 'ftCatalog') |
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| 56 | |||
| 57 | /** |
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| 58 | * Check that a fulltext catalog has been created yet. |
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| 59 | * |
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| 60 | * @param string $name Name of full text catalog to use |
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| 61 | * @return boolean |
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| 62 | */ |
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| 63 | public function fullTextCatalogExists($name = 'ftCatalog') |
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| 70 | |||
| 71 | /** |
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| 72 | * Sleep until the catalog has been fully rebuilt. This is a busy wait designed for situations |
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| 73 | * when you need to be sure the index is up to date - for example in unit tests. |
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| 74 | * |
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| 75 | * TODO: move this to Database class? Can we assume this will be useful for all databases? |
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| 76 | * Also see the wrapper functions "waitUntilIndexingFinished" in SearchFormTest and TranslatableSearchFormTest |
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| 77 | * |
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| 78 | * @param int $maxWaitingTime Time in seconds to wait for the database. |
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| 79 | */ |
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| 80 | public function waitUntilIndexingFinished($maxWaitingTime = 15) |
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| 100 | |||
| 101 | /** |
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| 102 | * Check if a fulltext index exists on a particular table name. |
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| 103 | * |
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| 104 | * @param string $tableName |
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| 105 | * @return boolean TRUE index exists | FALSE index does not exist | NULL no support |
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| 106 | */ |
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| 107 | public function fulltextIndexExists($tableName) |
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| 121 | |||
| 122 | /** |
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| 123 | * MSSQL stores the primary key column with an internal identifier, |
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| 124 | * so a lookup needs to be done to determine it. |
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| 125 | * |
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| 126 | * @param string $tableName Name of table with primary key column "ID" |
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| 127 | * @return string Internal identifier for primary key |
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| 128 | */ |
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| 129 | public function getPrimaryKey($tableName) |
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| 142 | |||
| 143 | /** |
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| 144 | * Gets the identity column of a table |
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| 145 | * |
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| 146 | * @param string $tableName |
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| 147 | * @return string|null |
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| 148 | */ |
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| 149 | public function getIdentityColumn($tableName) |
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| 163 | |||
| 164 | public function createDatabase($name) |
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| 168 | |||
| 169 | public function dropDatabase($name) |
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| 173 | |||
| 174 | public function databaseExists($name) |
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| 184 | |||
| 185 | public function databaseList() |
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| 189 | |||
| 190 | /** |
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| 191 | * Create a new table. |
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| 192 | * @param string $tableName The name of the table |
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| 193 | * @param array $fields A map of field names to field types |
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| 194 | * @param array $indexes A map of indexes |
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| 195 | * @param array $options An map of additional options. The available keys are as follows: |
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| 196 | * - 'MSSQLDatabase'/'MySQLDatabase'/'PostgreSQLDatabase' - database-specific options such as "engine" for MySQL. |
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| 197 | * - 'temporary' - If true, then a temporary table will be created |
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| 198 | * @param array $advancedOptions |
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| 199 | * @return string The table name generated. This may be different from the table name, for example with temporary tables. |
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| 200 | */ |
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| 201 | public function createTable($tableName, $fields = null, $indexes = null, $options = null, $advancedOptions = null) |
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| 235 | |||
| 236 | /** |
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| 237 | * Alter a table's schema. |
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| 238 | * @param string $tableName The name of the table to alter |
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| 239 | * @param array $newFields New fields, a map of field name => field schema |
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| 240 | * @param array $newIndexes New indexes, a map of index name => index type |
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| 241 | * @param array $alteredFields Updated fields, a map of field name => field schema |
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| 242 | * @param array $alteredIndexes Updated indexes, a map of index name => index type |
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| 243 | * @param array $alteredOptions |
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| 244 | * @param array $advancedOptions |
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| 245 | */ |
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| 246 | public function alterTable($tableName, $newFields = null, $newIndexes = null, $alteredFields = null, $alteredIndexes = null, $alteredOptions=null, $advancedOptions=null) |
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| 285 | |||
| 286 | /** |
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| 287 | * Given the table and column name, retrieve the constraint name for that column |
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| 288 | * in the table. |
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| 289 | * |
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| 290 | * @param string $tableName Table name column resides in |
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| 291 | * @param string $columnName Column name the constraint is for |
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| 292 | * @return string|null |
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| 293 | */ |
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| 294 | public function getConstraintName($tableName, $columnName) |
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| 303 | |||
| 304 | /** |
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| 305 | * Given a table and column name, return a check constraint clause for that column in |
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| 306 | * the table. |
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| 307 | * |
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| 308 | * This is an expensive query, so it is cached per-request and stored by table. The initial |
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| 309 | * call for a table that has not been cached will query all columns and store that |
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| 310 | * so subsequent calls are fast. |
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| 311 | * |
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| 312 | * @param string $tableName Table name column resides in |
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| 313 | * @param string $columnName Column name the constraint is for |
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| 314 | * @return string The check string |
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| 315 | */ |
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| 316 | public function getConstraintCheckClause($tableName, $columnName) |
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| 342 | |||
| 343 | /** |
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| 344 | * Return the name of the default constraint applied to $tableName.$colName. |
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| 345 | * Will return null if no such constraint exists |
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| 346 | * |
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| 347 | * @param string $tableName Name of the table |
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| 348 | * @param string $colName Name of the column |
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| 349 | * @return string|null |
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| 350 | */ |
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| 351 | protected function defaultConstraintName($tableName, $colName) |
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| 364 | |||
| 365 | /** |
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| 366 | * Get enum values from a constraint check clause. |
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| 367 | * |
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| 368 | * @param string $clause Check clause to parse values from |
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| 369 | * @return array Enum values |
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| 370 | */ |
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| 371 | protected function enumValuesFromCheckClause($clause) |
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| 383 | |||
| 384 | /* |
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| 385 | * Creates an ALTER expression for a column in MS SQL |
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| 386 | * |
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| 387 | * @param string $tableName Name of the table to be altered |
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| 388 | * @param string $colName Name of the column to be altered |
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| 389 | * @param string $colSpec String which contains conditions for a column |
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| 390 | * @return string |
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| 391 | */ |
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| 392 | protected function alterTableAlterColumn($tableName, $colName, $colSpec) |
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| 447 | |||
| 448 | public function renameTable($oldTableName, $newTableName) |
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| 452 | |||
| 453 | /** |
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| 454 | * Checks a table's integrity and repairs it if necessary. |
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| 455 | * NOTE: MSSQL does not appear to support any vacuum or optimise commands |
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| 456 | * |
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| 457 | * @var string $tableName The name of the table. |
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| 458 | * @return boolean Return true if the table has integrity after the method is complete. |
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| 459 | */ |
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| 460 | public function checkAndRepairTable($tableName) |
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| 464 | |||
| 465 | public function createField($tableName, $fieldName, $fieldSpec) |
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| 469 | |||
| 470 | /** |
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| 471 | * Change the database type of the given field. |
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| 472 | * @param string $tableName The name of the tbale the field is in. |
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| 473 | * @param string $fieldName The name of the field to change. |
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| 474 | * @param string $fieldSpec The new field specification |
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| 475 | */ |
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| 476 | public function alterField($tableName, $fieldName, $fieldSpec) |
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| 480 | |||
| 481 | public function renameField($tableName, $oldName, $newName) |
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| 485 | |||
| 486 | public function fieldList($table) |
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| 585 | |||
| 586 | /** |
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| 587 | * Create an index on a table. |
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| 588 | * @param string $tableName The name of the table. |
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| 589 | * @param string $indexName The name of the index. |
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| 590 | * @param string $indexSpec The specification of the index, see SS_Database::requireIndex() for more details. |
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| 591 | */ |
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| 592 | public function createIndex($tableName, $indexName, $indexSpec) |
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| 596 | |||
| 597 | /** |
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| 598 | * Return SQL for dropping and recreating an index |
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| 599 | * |
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| 600 | * @param string $tableName Name of table to create this index against |
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| 601 | * @param string $indexName Name of this index |
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| 602 | * @param array|string $indexSpec Index specification, either as a raw string |
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| 603 | * or parsed array form |
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| 604 | * @return string The SQL required to generate this index |
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| 605 | */ |
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| 606 | protected function getIndexSqlDefinition($tableName, $indexName, $indexSpec) |
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| 635 | |||
| 636 | public function alterIndex($tableName, $indexName, $indexSpec) |
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| 640 | |||
| 641 | /** |
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| 642 | * Return the list of indexes in a table. |
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| 643 | * @param string $table The table name. |
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| 644 | * @return array |
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| 645 | */ |
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| 646 | public function indexList($table) |
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| 695 | |||
| 696 | /** |
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| 697 | * For a given table name, get all the internal index names, |
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| 698 | * except for those that are primary keys and fulltext indexes. |
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| 699 | * |
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| 700 | * @return array |
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| 701 | */ |
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| 702 | public function indexNames($tableName) |
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| 711 | |||
| 712 | public function tableList() |
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| 720 | |||
| 721 | /** |
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| 722 | * Return a boolean type-formatted string |
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| 723 | * We use 'bit' so that we can do numeric-based comparisons |
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| 724 | * |
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| 725 | * @param array $values Contains a tokenised list of info about this data type |
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| 726 | * @return string |
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| 727 | */ |
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| 728 | public function boolean($values) |
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| 733 | |||
| 734 | /** |
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| 735 | * Return a date type-formatted string. |
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| 736 | * |
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| 737 | * @param array $values Contains a tokenised list of info about this data type |
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| 738 | * @return string |
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| 739 | */ |
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| 740 | public function date($values) |
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| 744 | |||
| 745 | /** |
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| 746 | * Return a decimal type-formatted string |
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| 747 | * |
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| 748 | * @param array $values Contains a tokenised list of info about this data type |
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| 749 | * @return string |
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| 750 | */ |
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| 751 | public function decimal($values) |
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| 767 | |||
| 768 | /** |
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| 769 | * Return a enum type-formatted string |
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| 770 | * |
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| 771 | * @param array $values Contains a tokenised list of info about this data type |
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| 772 | * @return string |
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| 773 | */ |
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| 774 | public function enum($values) |
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| 786 | |||
| 787 | /** |
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| 788 | * @todo Make this work like {@link MySQLDatabase::set()} |
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| 789 | */ |
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| 790 | public function set($values) |
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| 794 | |||
| 795 | /** |
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| 796 | * Return a float type-formatted string. |
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| 797 | * |
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| 798 | * @param array $values Contains a tokenised list of info about this data type |
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| 799 | * @return string |
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| 800 | */ |
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| 801 | public function float($values) |
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| 805 | |||
| 806 | /** |
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| 807 | * Return a int type-formatted string |
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| 808 | * |
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| 809 | * @param array $values Contains a tokenised list of info about this data type |
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| 810 | * @return string |
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| 811 | */ |
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| 812 | public function int($values) |
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| 816 | |||
| 817 | /** |
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| 818 | * Return a bigint type-formatted string |
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| 819 | * |
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| 820 | * @param array $values Contains a tokenised list of info about this data type |
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| 821 | * @return string |
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| 822 | */ |
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| 823 | public function bigint($values) |
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| 827 | |||
| 828 | /** |
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| 829 | * Return a datetime type-formatted string |
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| 830 | * For MS SQL, we simply return the word 'timestamp', no other parameters are necessary |
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| 831 | * |
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| 832 | * @param array $values Contains a tokenised list of info about this data type |
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| 833 | * @return string |
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| 834 | */ |
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| 835 | public function datetime($values) |
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| 839 | |||
| 840 | /** |
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| 841 | * Return a text type-formatted string |
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| 842 | * |
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| 843 | * @param array $values Contains a tokenised list of info about this data type |
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| 844 | * @return string |
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| 845 | */ |
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| 846 | public function text($values) |
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| 852 | |||
| 853 | /** |
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| 854 | * Return a time type-formatted string. |
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| 855 | * |
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| 856 | * @param array $values Contains a tokenised list of info about this data type |
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| 857 | * @return string |
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| 858 | */ |
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| 859 | public function time($values) |
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| 863 | |||
| 864 | /** |
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| 865 | * Return a varchar type-formatted string |
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| 866 | * |
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| 867 | * @param array $values Contains a tokenised list of info about this data type |
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| 868 | * @return string |
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| 869 | */ |
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| 870 | public function varchar($values) |
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| 876 | |||
| 877 | /** |
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| 878 | * Return a 4 digit numeric type. |
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| 879 | * |
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| 880 | * @param array $values |
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| 881 | * @return string |
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| 882 | */ |
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| 883 | public function year($values) |
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| 887 | |||
| 888 | /** |
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| 889 | * This returns the column which is the primary key for each table |
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| 890 | * |
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| 891 | * @param bool $asDbValue |
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| 892 | * @param bool $hasAutoIncPK |
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| 893 | * @return string |
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| 894 | */ |
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| 895 | public function IdColumn($asDbValue = false, $hasAutoIncPK = true) |
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| 905 | |||
| 906 | public function hasTable($tableName) |
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| 913 | |||
| 914 | /** |
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| 915 | * Returns the values of the given enum field |
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| 916 | * NOTE: Experimental; introduced for db-abstraction and may changed before 2.4 is released. |
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| 917 | * |
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| 918 | * @param string $tableName |
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| 919 | * @param string $fieldName |
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| 920 | * @return array |
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| 921 | */ |
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| 922 | public function enumValuesForField($tableName, $fieldName) |
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| 934 | |||
| 935 | /** |
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| 936 | * This is a lookup table for data types. |
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| 937 | * |
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| 938 | * For instance, MSSQL uses 'BIGINT', while MySQL uses 'UNSIGNED' |
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| 939 | * and PostgreSQL uses 'INT'. |
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| 940 | * |
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| 941 | * @param string $type |
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| 942 | * @return string |
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| 943 | */ |
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| 944 | public function dbDataType($type) |
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| 955 | |||
| 956 | protected function indexKey($table, $index, $spec) |
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| 960 | } |
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| 961 |
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 sub-classes 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 parent class: