Complex classes like DB 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 DB, and based on these observations, apply Extract Interface, too.
1 | <?php |
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22 | class DB { |
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23 | |||
24 | /** |
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25 | * This constant was added in SilverStripe 2.4 to indicate that SQL-queries |
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26 | * should now use ANSI-compatible syntax. The most notable affect of this |
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27 | * change is that table and field names should be escaped with double quotes |
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28 | * and not backticks |
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29 | */ |
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30 | const USE_ANSI_SQL = true; |
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31 | |||
32 | |||
33 | /** |
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34 | * The global database connection. |
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35 | * @var Database |
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36 | */ |
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37 | private static $connections = array(); |
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38 | |||
39 | /** |
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40 | * The last SQL query run. |
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41 | * @var string |
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42 | */ |
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43 | public static $lastQuery; |
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44 | |||
45 | /** |
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46 | * Internal flag to keep track of when db connection was attempted. |
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47 | */ |
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48 | private static $connection_attempted = false; |
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49 | |||
50 | /** |
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51 | * Set the global database connection. |
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52 | * Pass an object that's a subclass of SS_Database. This object will be used when {@link DB::query()} |
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53 | * is called. |
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54 | * |
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55 | * @param Database $connection The connecton object to set as the connection. |
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56 | * @param string $name The name to give to this connection. If you omit this argument, the connection |
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57 | * will be the default one used by the ORM. However, you can store other named connections to |
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58 | * be accessed through DB::get_conn($name). This is useful when you have an application that |
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59 | * needs to connect to more than one database. |
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60 | */ |
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61 | public static function set_conn(Database $connection, $name = 'default') { |
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64 | |||
65 | /** |
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66 | * Get the global database connection. |
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67 | * |
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68 | * @param string $name An optional name given to a connection in the DB::setConn() call. If omitted, |
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69 | * the default connection is returned. |
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70 | * @return Database |
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71 | */ |
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72 | public static function get_conn($name = 'default') { |
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78 | |||
79 | /** |
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80 | * @deprecated since version 4.0 Use DB::get_conn instead |
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81 | * @todo PSR-2 standardisation will probably un-deprecate this |
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82 | */ |
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83 | public static function getConn($name = 'default') { |
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87 | |||
88 | /** |
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89 | * Retrieves the schema manager for the current database |
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90 | * |
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91 | * @param string $name An optional name given to a connection in the DB::setConn() call. If omitted, |
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92 | * the default connection is returned. |
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93 | * @return DBSchemaManager |
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94 | */ |
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95 | public static function get_schema($name = 'default') { |
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102 | |||
103 | /** |
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104 | * Builds a sql query with the specified connection |
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105 | * |
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106 | * @param SQLExpression $expression The expression object to build from |
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107 | * @param array $parameters Out parameter for the resulting query parameters |
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108 | * @param string $name An optional name given to a connection in the DB::setConn() call. If omitted, |
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109 | * the default connection is returned. |
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110 | * @return string The resulting SQL as a string |
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111 | */ |
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112 | public static function build_sql(SQLExpression $expression, &$parameters, $name = 'default') { |
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121 | |||
122 | /** |
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123 | * Retrieves the connector object for the current database |
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124 | * |
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125 | * @param string $name An optional name given to a connection in the DB::setConn() call. If omitted, |
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126 | * the default connection is returned. |
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127 | * @return DBConnector |
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128 | */ |
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129 | public static function get_connector($name = 'default') { |
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136 | |||
137 | /** |
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138 | * Set an alternative database in a browser cookie, |
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139 | * with the cookie lifetime set to the browser session. |
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140 | * This is useful for integration testing on temporary databases. |
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141 | * |
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142 | * There is a strict naming convention for temporary databases to avoid abuse: |
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143 | * <prefix> (default: 'ss_') + tmpdb + <7 digits> |
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144 | * As an additional security measure, temporary databases will |
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145 | * be ignored in "live" mode. |
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146 | * |
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147 | * Note that the database will be set on the next request. |
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148 | * Set it to null to revert to the main database. |
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149 | * @param string $name |
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150 | */ |
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151 | public static function set_alternative_database_name($name = null) { |
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187 | |||
188 | /** |
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189 | * Get the name of the database in use |
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190 | */ |
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191 | public static function get_alternative_database_name() { |
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212 | |||
213 | /** |
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214 | * Determines if the name is valid, as a security |
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215 | * measure against setting arbitrary databases. |
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216 | * |
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217 | * @param String $name |
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218 | * @return Boolean |
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219 | */ |
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220 | public static function valid_alternative_database_name($name) { |
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227 | |||
228 | /** |
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229 | * Connect to a database. |
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230 | * |
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231 | * Given the database configuration, this method will create the correct |
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232 | * subclass of {@link SS_Database}. |
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233 | * |
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234 | * @param array $databaseConfig A map of options. The 'type' is the name of the |
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235 | * subclass of SS_Database to use. For the rest of the options, see the specific class. |
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236 | * @param string $label identifier for the connection |
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237 | * @return Database |
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238 | */ |
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239 | public static function connect($databaseConfig, $label = 'default') { |
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263 | |||
264 | /** |
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265 | * Returns true if a database connection has been attempted. |
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266 | * In particular, it lets the caller know if we're still so early in the execution pipeline that |
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267 | * we haven't even tried to connect to the database yet. |
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268 | */ |
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269 | public static function connection_attempted() { |
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272 | |||
273 | /** |
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274 | * Execute the given SQL query. |
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275 | * @param string $sql The SQL query to execute |
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276 | * @param int $errorLevel The level of error reporting to enable for the query |
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277 | * @return Query |
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278 | */ |
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279 | public static function query($sql, $errorLevel = E_USER_ERROR) { |
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284 | |||
285 | /** |
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286 | * Helper function for generating a list of parameter placeholders for the |
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287 | * given argument(s) |
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288 | * |
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289 | * @param array|integer $input An array of items needing placeholders, or a |
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290 | * number to specify the number of placeholders |
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291 | * @param string $join The string to join each placeholder together with |
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292 | * @return string|null Either a list of placeholders, or null |
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293 | */ |
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294 | public static function placeholders($input, $join = ', ') { |
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305 | |||
306 | /** |
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307 | * @param string $sql The parameterised query |
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308 | * @param array $parameters The parameters to inject into the query |
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309 | * |
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310 | * @return string |
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311 | */ |
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312 | public static function inline_parameters($sql, $parameters) { |
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359 | |||
360 | /** |
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361 | * Execute the given SQL parameterised query with the specified arguments |
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362 | * |
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363 | * @param string $sql The SQL query to execute. The ? character will denote parameters. |
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364 | * @param array $parameters An ordered list of arguments. |
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365 | * @param int $errorLevel The level of error reporting to enable for the query |
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366 | * @return Query |
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367 | */ |
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368 | public static function prepared_query($sql, $parameters, $errorLevel = E_USER_ERROR) { |
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373 | |||
374 | /** |
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375 | * Execute a complex manipulation on the database. |
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376 | * A manipulation is an array of insert / or update sequences. The keys of the array are table names, |
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377 | * and the values are map containing 'command' and 'fields'. Command should be 'insert' or 'update', |
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378 | * and fields should be a map of field names to field values, including quotes. The field value can |
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379 | * also be a SQL function or similar. |
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380 | * |
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381 | * Example: |
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382 | * <code> |
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383 | * array( |
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384 | * // Command: insert |
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385 | * "table name" => array( |
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386 | * "command" => "insert", |
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387 | * "fields" => array( |
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388 | * "ClassName" => "'MyClass'", // if you're setting a literal, you need to escape and provide quotes |
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389 | * "Created" => "now()", // alternatively, you can call DB functions |
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390 | * "ID" => 234, |
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391 | * ), |
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392 | * "id" => 234 // an alternative to providing ID in the fields list |
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393 | * ), |
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394 | * |
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395 | * // Command: update |
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396 | * "other table" => array( |
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397 | * "command" => "update", |
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398 | * "fields" => array( |
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399 | * "ClassName" => "'MyClass'", |
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400 | * "LastEdited" => "now()", |
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401 | * ), |
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402 | * "where" => "ID = 234", |
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403 | * "id" => 234 // an alternative to providing a where clause |
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404 | * ), |
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405 | * ) |
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406 | * </code> |
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407 | * |
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408 | * You'll note that only one command on a given table can be called. |
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409 | * That's a limitation of the system that's due to it being written for {@link DataObject::write()}, |
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410 | * which needs to do a single write on a number of different tables. |
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411 | * |
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412 | * @todo Update this to support paramaterised queries |
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413 | * |
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414 | * @param array $manipulation |
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415 | */ |
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416 | public static function manipulate($manipulation) { |
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420 | |||
421 | /** |
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422 | * Get the autogenerated ID from the previous INSERT query. |
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423 | * |
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424 | * @param string $table |
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425 | * @return int |
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426 | */ |
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427 | public static function get_generated_id($table) { |
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430 | |||
431 | /** |
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432 | * Check if the connection to the database is active. |
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433 | * |
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434 | * @return boolean |
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435 | */ |
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436 | public static function is_active() { |
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439 | |||
440 | /** |
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441 | * Create the database and connect to it. This can be called if the |
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442 | * initial database connection is not successful because the database |
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443 | * does not exist. |
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444 | * |
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445 | * @param string $database Name of database to create |
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446 | * @return boolean Returns true if successful |
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447 | */ |
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448 | public static function create_database($database) { |
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451 | |||
452 | /** |
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453 | * Create a new table. |
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454 | * @param string $table The name of the table |
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455 | * @param array$fields A map of field names to field types |
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456 | * @param array $indexes A map of indexes |
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457 | * @param array $options An map of additional options. The available keys are as follows: |
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458 | * - 'MSSQLDatabase'/'MySQLDatabase'/'PostgreSQLDatabase' - database-specific options such as "engine" |
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459 | * for MySQL. |
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460 | * - 'temporary' - If true, then a temporary table will be created |
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461 | * @param array $advancedOptions Advanced creation options |
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462 | * @return string The table name generated. This may be different from the table name, for example with |
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463 | * temporary tables. |
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464 | */ |
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465 | public static function create_table($table, $fields = null, $indexes = null, $options = null, |
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470 | |||
471 | /** |
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472 | * Create a new field on a table. |
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473 | * @param string $table Name of the table. |
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474 | * @param string $field Name of the field to add. |
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475 | * @param string $spec The field specification, eg 'INTEGER NOT NULL' |
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476 | */ |
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477 | public static function create_field($table, $field, $spec) { |
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480 | |||
481 | /** |
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482 | * Generate the following table in the database, modifying whatever already exists |
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483 | * as necessary. |
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484 | * |
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485 | * @param string $table The name of the table |
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486 | * @param string $fieldSchema A list of the fields to create, in the same form as DataObject::$db |
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487 | * @param string $indexSchema A list of indexes to create. The keys of the array are the names of the index. |
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488 | * The values of the array can be one of: |
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489 | * - true: Create a single column index on the field named the same as the index. |
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490 | * - array('fields' => array('A','B','C'), 'type' => 'index/unique/fulltext'): This gives you full |
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491 | * control over the index. |
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492 | * @param boolean $hasAutoIncPK A flag indicating that the primary key on this table is an autoincrement type |
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493 | * @param string $options SQL statement to append to the CREATE TABLE call. |
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494 | * @param array $extensions List of extensions |
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495 | */ |
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496 | public static function require_table($table, $fieldSchema = null, $indexSchema = null, $hasAutoIncPK = true, |
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501 | |||
502 | /** |
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503 | * Generate the given field on the table, modifying whatever already exists as necessary. |
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504 | * |
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505 | * @param string $table The table name. |
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506 | * @param string $field The field name. |
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507 | * @param string $spec The field specification. |
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508 | */ |
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509 | public static function require_field($table, $field, $spec) { |
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512 | |||
513 | /** |
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514 | * Generate the given index in the database, modifying whatever already exists as necessary. |
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515 | * |
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516 | * @param string $table The table name. |
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517 | * @param string $index The index name. |
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518 | * @param string|boolean $spec The specification of the index. See requireTable() for more information. |
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519 | */ |
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520 | public static function require_index($table, $index, $spec) { |
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523 | |||
524 | /** |
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525 | * If the given table exists, move it out of the way by renaming it to _obsolete_(tablename). |
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526 | * |
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527 | * @param string $table The table name. |
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528 | */ |
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529 | public static function dont_require_table($table) { |
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532 | |||
533 | /** |
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534 | * See {@link SS_Database->dontRequireField()}. |
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535 | * |
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536 | * @param string $table The table name. |
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537 | * @param string $fieldName The field name not to require |
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538 | */ |
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539 | public static function dont_require_field($table, $fieldName) { |
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542 | |||
543 | /** |
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544 | * Checks a table's integrity and repairs it if necessary. |
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545 | * |
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546 | * @param string $table The name of the table. |
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547 | * @return boolean Return true if the table has integrity after the method is complete. |
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548 | */ |
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549 | public static function check_and_repair_table($table) { |
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552 | |||
553 | /** |
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554 | * Return the number of rows affected by the previous operation. |
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555 | * |
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556 | * @return integer The number of affected rows |
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557 | */ |
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558 | public static function affected_rows() { |
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561 | |||
562 | /** |
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563 | * Returns a list of all tables in the database. |
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564 | * The table names will be in lower case. |
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565 | * |
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566 | * @return array The list of tables |
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567 | */ |
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568 | public static function table_list() { |
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571 | |||
572 | /** |
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573 | * Get a list of all the fields for the given table. |
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574 | * Returns a map of field name => field spec. |
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575 | * |
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576 | * @param string $table The table name. |
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577 | * @return array The list of fields |
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578 | */ |
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579 | public static function field_list($table) { |
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582 | |||
583 | /** |
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584 | * Enable supression of database messages. |
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585 | */ |
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586 | public static function quiet() { |
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589 | |||
590 | /** |
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591 | * Show a message about database alteration |
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592 | * |
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593 | * @param string $message to display |
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594 | * @param string $type one of [created|changed|repaired|obsolete|deleted|error] |
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595 | */ |
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596 | public static function alteration_message($message, $type = "") { |
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599 | |||
600 | } |
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601 |
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