gnu-social/lib/schema.php

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<?php
/**
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* StatusNet, the distributed open-source microblogging tool
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*
* Database schema utilities
*
* PHP version 5
*
* LICENCE: This program is free software: you can redistribute it and/or modify
* it under the terms of the GNU Affero General Public License as published by
* the Free Software Foundation, either version 3 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU Affero General Public License for more details.
*
* You should have received a copy of the GNU Affero General Public License
* along with this program. If not, see <http://www.gnu.org/licenses/>.
*
* @category Database
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* @package StatusNet
* @author Evan Prodromou <evan@status.net>
* @copyright 2009 StatusNet, Inc.
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* @license http://www.fsf.org/licensing/licenses/agpl-3.0.html GNU Affero General Public License version 3.0
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* @link http://status.net/
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*/
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if (!defined('STATUSNET')) {
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exit(1);
}
/**
* Class representing the database schema
*
* A class representing the database schema. Can be used to
* manipulate the schema -- especially for plugins and upgrade
* utilities.
*
* @category Database
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* @package StatusNet
* @author Evan Prodromou <evan@status.net>
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* @license http://www.fsf.org/licensing/licenses/agpl-3.0.html GNU Affero General Public License version 3.0
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* @link http://status.net/
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*/
class Schema
{
static $_single = null;
protected $conn = null;
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/**
* Constructor. Only run once for singleton object.
*/
protected function __construct()
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{
// XXX: there should be an easier way to do this.
$user = new User();
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$this->conn = $user->getDatabaseConnection();
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$user->free();
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unset($user);
}
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/**
* Main public entry point. Use this to get
* the singleton object.
*
* @return Schema the (single) Schema object
*/
static function get()
{
if (empty(self::$_single)) {
self::$_single = new Schema();
}
return self::$_single;
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}
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/**
* Returns a TableDef object for the table
* in the schema with the given name.
*
* Throws an exception if the table is not found.
*
* @param string $name Name of the table to get
*
* @return TableDef tabledef for that table.
*/
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public function getTableDef($name)
{
$res =& $this->conn->query('DESCRIBE ' . $name);
if (PEAR::isError($res)) {
throw new Exception($res->getMessage());
}
$td = new TableDef();
$td->name = $name;
$td->columns = array();
$row = array();
while ($res->fetchInto($row, DB_FETCHMODE_ASSOC)) {
$cd = new ColumnDef();
$cd->name = $row['Field'];
$packed = $row['Type'];
if (preg_match('/^(\w+)\((\d+)\)$/', $packed, $match)) {
$cd->type = $match[1];
$cd->size = $match[2];
} else {
$cd->type = $packed;
}
$cd->nullable = ($row['Null'] == 'YES') ? true : false;
$cd->key = $row['Key'];
$cd->default = $row['Default'];
$cd->extra = $row['Extra'];
$td->columns[] = $cd;
}
return $td;
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}
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/**
* Gets a ColumnDef object for a single column.
*
* Throws an exception if the table is not found.
*
* @param string $table name of the table
* @param string $column name of the column
*
* @return ColumnDef definition of the column or null
* if not found.
*/
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public function getColumnDef($table, $column)
{
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$td = $this->getTableDef($table);
foreach ($td->columns as $cd) {
if ($cd->name == $column) {
return $cd;
}
}
return null;
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}
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/**
* Creates a table with the given names and columns.
*
* @param string $name Name of the table
* @param array $columns Array of ColumnDef objects
* for new table.
*
* @return boolean success flag
*/
public function createTable($name, $columns)
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{
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$uniques = array();
$primary = array();
$indices = array();
$sql = "CREATE TABLE $name (\n";
for ($i = 0; $i < count($columns); $i++) {
$cd =& $columns[$i];
if ($i > 0) {
$sql .= ",\n";
}
$sql .= $this->_columnSql($cd);
switch ($cd->key) {
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case 'UNI':
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$uniques[] = $cd->name;
break;
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case 'PRI':
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$primary[] = $cd->name;
break;
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case 'MUL':
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$indices[] = $cd->name;
break;
}
}
if (count($primary) > 0) { // it really should be...
$sql .= ",\nconstraint primary key (" . implode(',', $primary) . ")";
}
foreach ($uniques as $u) {
$sql .= ",\nunique index {$name}_{$u}_idx ($u)";
}
foreach ($indices as $i) {
$sql .= ",\nindex {$name}_{$i}_idx ($i)";
}
$sql .= "); ";
$res =& $this->conn->query($sql);
if (PEAR::isError($res)) {
throw new Exception($res->getMessage());
}
return true;
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}
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/**
* Drops a table from the schema
*
* Throws an exception if the table is not found.
*
* @param string $name Name of the table to drop
*
* @return boolean success flag
*/
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public function dropTable($name)
{
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$res =& $this->conn->query("DROP TABLE $name");
if (PEAR::isError($res)) {
throw new Exception($res->getMessage());
}
return true;
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}
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/**
* Adds an index to a table.
*
* If no name is provided, a name will be made up based
* on the table name and column names.
*
* Throws an exception on database error, esp. if the table
* does not exist.
*
* @param string $table Name of the table
* @param array $columnNames Name of columns to index
* @param string $name (Optional) name of the index
*
* @return boolean success flag
*/
public function createIndex($table, $columnNames, $name=null)
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{
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if (!is_array($columnNames)) {
$columnNames = array($columnNames);
}
if (empty($name)) {
$name = "$table_".implode("_", $columnNames)."_idx";
}
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$res =& $this->conn->query("ALTER TABLE $table ".
"ADD INDEX $name (".
implode(",", $columnNames).")");
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if (PEAR::isError($res)) {
throw new Exception($res->getMessage());
}
return true;
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}
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/**
* Drops a named index from a table.
*
* @param string $table name of the table the index is on.
* @param string $name name of the index
*
* @return boolean success flag
*/
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public function dropIndex($table, $name)
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{
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$res =& $this->conn->query("ALTER TABLE $table DROP INDEX $name");
if (PEAR::isError($res)) {
throw new Exception($res->getMessage());
}
return true;
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}
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/**
* Adds a column to a table
*
* @param string $table name of the table
* @param ColumnDef $columndef Definition of the new
* column.
*
* @return boolean success flag
*/
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public function addColumn($table, $columndef)
{
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$sql = "ALTER TABLE $table ADD COLUMN " . $this->_columnSql($columndef);
$res =& $this->conn->query($sql);
if (PEAR::isError($res)) {
throw new Exception($res->getMessage());
}
return true;
}
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/**
* Modifies a column in the schema.
*
* The name must match an existing column and table.
*
* @param string $table name of the table
* @param ColumnDef $columndef new definition of the column.
*
* @return boolean success flag
*/
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public function modifyColumn($table, $columndef)
{
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$sql = "ALTER TABLE $table MODIFY COLUMN " .
$this->_columnSql($columndef);
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$res =& $this->conn->query($sql);
if (PEAR::isError($res)) {
throw new Exception($res->getMessage());
}
return true;
}
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/**
* Drops a column from a table
*
* The name must match an existing column.
*
* @param string $table name of the table
* @param string $columnName name of the column to drop
*
* @return boolean success flag
*/
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public function dropColumn($table, $columnName)
{
$sql = "ALTER TABLE $table DROP COLUMN $columnName";
$res =& $this->conn->query($sql);
if (PEAR::isError($res)) {
throw new Exception($res->getMessage());
}
return true;
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}
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/**
* Ensures that a table exists with the given
* name and the given column definitions.
*
* If the table does not yet exist, it will
* create the table. If it does exist, it will
* alter the table to match the column definitions.
*
* @param string $tableName name of the table
* @param array $columns array of ColumnDef
* objects for the table
*
* @return boolean success flag
*/
public function ensureTable($tableName, $columns)
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{
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// XXX: DB engine portability -> toilet
try {
$td = $this->getTableDef($tableName);
} catch (Exception $e) {
if (preg_match('/no such table/', $e->getMessage())) {
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return $this->createTable($tableName, $columns);
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} else {
throw $e;
}
}
$cur = $this->_names($td->columns);
$new = $this->_names($columns);
$toadd = array_diff($new, $cur);
$todrop = array_diff($cur, $new);
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$same = array_intersect($new, $cur);
$tomod = array();
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foreach ($same as $m) {
$curCol = $this->_byName($td->columns, $m);
$newCol = $this->_byName($columns, $m);
if (!$newCol->equals($curCol)) {
$tomod[] = $newCol->name;
}
}
if (count($toadd) + count($todrop) + count($tomod) == 0) {
// nothing to do
return true;
}
// For efficiency, we want this all in one
// query, instead of using our methods.
$phrase = array();
foreach ($toadd as $columnName) {
$cd = $this->_byName($columns, $columnName);
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$phrase[] = 'ADD COLUMN ' . $this->_columnSql($cd);
}
foreach ($todrop as $columnName) {
$phrase[] = 'DROP COLUMN ' . $columnName;
}
foreach ($tomod as $columnName) {
$cd = $this->_byName($columns, $columnName);
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$phrase[] = 'MODIFY COLUMN ' . $this->_columnSql($cd);
}
$sql = 'ALTER TABLE ' . $tableName . ' ' . implode(', ', $phrase);
$res =& $this->conn->query($sql);
if (PEAR::isError($res)) {
throw new Exception($res->getMessage());
}
return true;
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}
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/**
* Returns the array of names from an array of
* ColumnDef objects.
*
* @param array $cds array of ColumnDef objects
*
* @return array strings for name values
*/
private function _names($cds)
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{
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$names = array();
foreach ($cds as $cd) {
$names[] = $cd->name;
}
return $names;
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}
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/**
* Get a ColumnDef from an array matching
* name.
*
* @param array $cds Array of ColumnDef objects
* @param string $name Name of the column
*
* @return ColumnDef matching item or null if no match.
*/
private function _byName($cds, $name)
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{
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foreach ($cds as $cd) {
if ($cd->name == $name) {
return $cd;
}
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}
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return null;
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}
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/**
* Return the proper SQL for creating or
* altering a column.
*
* Appropriate for use in CREATE TABLE or
* ALTER TABLE statements.
*
* @param ColumnDef $cd column to create
*
* @return string correct SQL for that column
*/
private function _columnSql($cd)
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{
$sql = "{$cd->name} ";
if (!empty($cd->size)) {
$sql .= "{$cd->type}({$cd->size}) ";
} else {
$sql .= "{$cd->type} ";
}
if (!empty($cd->default)) {
$sql .= "default {$cd->default} ";
} else {
$sql .= ($cd->nullable) ? "null " : "not null ";
}
return $sql;
}
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}