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Drupal example source code file (schema.inc)

This example Drupal source code file (schema.inc) is included in the DevDaily.com "Drupal Source Code Warehouse" project. The intent of this project is to help you "Learn Drupal by Example".

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The schema.inc Drupal example source code

<?php
// $Id: schema.inc,v 1.44 2010/12/08 06:38:59 webchick Exp $

/**
 * @file
 * Database schema code for MySQL database servers.
 */


/**
 * @ingroup schemaapi
 * @{
 */

class DatabaseSchema_mysql extends DatabaseSchema {

  /**
   * Maximum length of a table comment in MySQL.
   */
  const COMMENT_MAX_TABLE = 60;

  /**
   * Maximum length of a column comment in MySQL.
   */
  const COMMENT_MAX_COLUMN = 255;

  /**
   * Get information about the table and database name from the prefix.
   *
   * @return
   *   A keyed array with information about the database, table name and prefix.
   */
  protected function getPrefixInfo($table = 'default', $add_prefix = TRUE) {
    $info = array('prefix' => $this->connection->tablePrefix($table));
    if ($add_prefix) {
      $table = $info['prefix'] . $table;
    }
    if (($pos = strpos($table, '.')) !== FALSE) {
      $info['database'] = substr($table, 0, $pos);
      $info['table'] = substr($table, ++$pos);
    }
    else {
      $db_info = Database::getConnectionInfo();
      $info['database'] = $db_info['default']['database'];
      $info['table'] = $table;
    }
    return $info;
  }

  /**
   * Build a condition to match a table name against a standard information_schema.
   *
   * MySQL uses databases like schemas rather than catalogs so when we build
   * a condition to query the information_schema.tables, we set the default
   * database as the schema unless specified otherwise, and exclude table_catalog
   * from the condition criteria.
   */
  protected function buildTableNameCondition($table_name, $operator = '=', $add_prefix = TRUE) {
    $info = $this->connection->getConnectionOptions();

    $table_info = $this->getPrefixInfo($table_name, $add_prefix);

    $condition = new DatabaseCondition('AND');
    $condition->condition('table_schema', $table_info['database']);
    $condition->condition('table_name', $table_info['table'], $operator);
    return $condition;
  }

  /**
   * Generate SQL to create a new table from a Drupal schema definition.
   *
   * @param $name
   *   The name of the table to create.
   * @param $table
   *   A Schema API table definition array.
   * @return
   *   An array of SQL statements to create the table.
   */
  protected function createTableSql($name, $table) {
    $info = $this->connection->getConnectionOptions();

    // Provide defaults if needed.
    $table += array(
      'mysql_engine' => 'InnoDB',
      'mysql_character_set' => 'utf8',
    );

    $sql = "CREATE TABLE {" . $name . "} (\n";

    // Add the SQL statement for each field.
    foreach ($table['fields'] as $field_name => $field) {
      $sql .= $this->createFieldSql($field_name, $this->processField($field)) . ", \n";
    }

    // Process keys & indexes.
    $keys = $this->createKeysSql($table);
    if (count($keys)) {
      $sql .= implode(", \n", $keys) . ", \n";
    }

    // Remove the last comma and space.
    $sql = substr($sql, 0, -3) . "\n) ";

    $sql .= 'ENGINE = ' . $table['mysql_engine'] . ' DEFAULT CHARACTER SET ' . $table['mysql_character_set'];
    // By default, MySQL uses the default collation for new tables, which is
    // 'utf8_general_ci' for utf8. If an alternate collation has been set, it
    // needs to be explicitly specified.
    // @see DatabaseConnection_mysql
    if (!empty($info['collation'])) {
      $sql .= ' COLLATE ' . $info['collation'];
    }

    // Add table comment.
    if (!empty($table['description'])) {
      $sql .= ' COMMENT ' . $this->prepareComment($table['description'], self::COMMENT_MAX_TABLE);
    }

    return array($sql);
  }

  /**
   * Create an SQL string for a field to be used in table creation or alteration.
   *
   * Before passing a field out of a schema definition into this function it has
   * to be processed by _db_process_field().
   *
   * @param $name
   *   Name of the field.
   * @param $spec
   *   The field specification, as per the schema data structure format.
   */
  protected function createFieldSql($name, $spec) {
    $sql = "`" . $name . "` " . $spec['mysql_type'];

    if (in_array($spec['mysql_type'], array('VARCHAR', 'CHAR', 'TINYTEXT', 'MEDIUMTEXT', 'LONGTEXT', 'TEXT')) && isset($spec['length'])) {
      $sql .= '(' . $spec['length'] . ')';
    }
    elseif (isset($spec['precision']) && isset($spec['scale'])) {
      $sql .= '(' . $spec['precision'] . ', ' . $spec['scale'] . ')';
    }

    if (!empty($spec['unsigned'])) {
      $sql .= ' unsigned';
    }

    if (isset($spec['not null'])) {
      if ($spec['not null']) {
        $sql .= ' NOT NULL';
      }
      else {
        $sql .= ' NULL';
      }
    }

    if (!empty($spec['auto_increment'])) {
      $sql .= ' auto_increment';
    }

    // $spec['default'] can be NULL, so we explicitly check for the key here.
    if (array_key_exists('default', $spec)) {
      if (is_string($spec['default'])) {
        $spec['default'] = "'" . $spec['default'] . "'";
      }
      elseif (!isset($spec['default'])) {
        $spec['default'] = 'NULL';
      }
      $sql .= ' DEFAULT ' . $spec['default'];
    }

    if (empty($spec['not null']) && !isset($spec['default'])) {
      $sql .= ' DEFAULT NULL';
    }

    // Add column comment.
    if (!empty($spec['description'])) {
      $sql .= ' COMMENT ' . $this->prepareComment($spec['description'], self::COMMENT_MAX_COLUMN);
    }

    return $sql;
  }

  /**
   * Set database-engine specific properties for a field.
   *
   * @param $field
   *   A field description array, as specified in the schema documentation.
   */
  protected function processField($field) {

    if (!isset($field['size'])) {
      $field['size'] = 'normal';
    }

    // Set the correct database-engine specific datatype.
    // In case one is already provided, force it to uppercase.
    if (isset($field['mysql_type'])) {
      $field['mysql_type'] = drupal_strtoupper($field['mysql_type']);
    }
    else {
      $map = $this->getFieldTypeMap();
      $field['mysql_type'] = $map[$field['type'] . ':' . $field['size']];
    }

    if (isset($field['type']) && $field['type'] == 'serial') {
      $field['auto_increment'] = TRUE;
    }

    return $field;
  }

  public function getFieldTypeMap() {
    // Put :normal last so it gets preserved by array_flip. This makes
    // it much easier for modules (such as schema.module) to map
    // database types back into schema types.
    // $map does not use drupal_static as its value never changes.
    static $map = array(
      'varchar:normal'  => 'VARCHAR',
      'char:normal'     => 'CHAR',

      'text:tiny'       => 'TINYTEXT',
      'text:small'      => 'TINYTEXT',
      'text:medium'     => 'MEDIUMTEXT',
      'text:big'        => 'LONGTEXT',
      'text:normal'     => 'TEXT',

      'serial:tiny'     => 'TINYINT',
      'serial:small'    => 'SMALLINT',
      'serial:medium'   => 'MEDIUMINT',
      'serial:big'      => 'BIGINT',
      'serial:normal'   => 'INT',

      'int:tiny'        => 'TINYINT',
      'int:small'       => 'SMALLINT',
      'int:medium'      => 'MEDIUMINT',
      'int:big'         => 'BIGINT',
      'int:normal'      => 'INT',

      'float:tiny'      => 'FLOAT',
      'float:small'     => 'FLOAT',
      'float:medium'    => 'FLOAT',
      'float:big'       => 'DOUBLE',
      'float:normal'    => 'FLOAT',

      'numeric:normal'  => 'DECIMAL',

      'blob:big'        => 'LONGBLOB',
      'blob:normal'     => 'BLOB',
    );
    return $map;
  }

  protected function createKeysSql($spec) {
    $keys = array();

    if (!empty($spec['primary key'])) {
      $keys[] = 'PRIMARY KEY (' . $this->createKeysSqlHelper($spec['primary key']) . ')';
    }
    if (!empty($spec['unique keys'])) {
      foreach ($spec['unique keys'] as $key => $fields) {
        $keys[] = 'UNIQUE KEY `' . $key . '` (' . $this->createKeysSqlHelper($fields) . ')';
      }
    }
    if (!empty($spec['indexes'])) {
      foreach ($spec['indexes'] as $index => $fields) {
        $keys[] = 'INDEX `' . $index . '` (' . $this->createKeysSqlHelper($fields) . ')';
      }
    }

    return $keys;
  }

  protected function createKeySql($fields) {
    $return = array();
    foreach ($fields as $field) {
      if (is_array($field)) {
        $return[] = '`' . $field[0] . '`(' . $field[1] . ')';
      }
      else {
        $return[] = '`' . $field . '`';
      }
    }
    return implode(', ', $return);
  }

  protected function createKeysSqlHelper($fields) {
    $return = array();
    foreach ($fields as $field) {
      if (is_array($field)) {
        $return[] = '`' . $field[0] . '`(' . $field[1] . ')';
      }
      else {
        $return[] = '`' . $field . '`';
      }
    }
    return implode(', ', $return);
  }

  public function renameTable($table, $new_name) {
    if (!$this->tableExists($table)) {
      throw new DatabaseSchemaObjectDoesNotExistException(t("Cannot rename %table to %table_new: table %table doesn't exist.", array('%table' => $table, '%table_new' => $new_name)));
    }
    if ($this->tableExists($new_name)) {
      throw new DatabaseSchemaObjectExistsException(t("Cannot rename %table to %table_new: table %table_new already exists.", array('%table' => $table, '%table_new' => $new_name)));
    }

    $info = $this->getPrefixInfo($new_name);
    return $this->connection->query('ALTER TABLE {' . $table . '} RENAME TO `' . $info['table'] . '`');
  }

  public function dropTable($table) {
    if (!$this->tableExists($table)) {
      return FALSE;
    }

    $this->connection->query('DROP TABLE {' . $table . '}');
    return TRUE;
  }

  public function addField($table, $field, $spec, $keys_new = array()) {
    if (!$this->tableExists($table)) {
      throw new DatabaseSchemaObjectDoesNotExistException(t("Cannot add field %table.%field: table doesn't exist.", array('%field' => $field, '%table' => $table)));
    }
    if ($this->fieldExists($table, $field)) {
      throw new DatabaseSchemaObjectExistsException(t("Cannot add field %table.%field: field already exists.", array('%field' => $field, '%table' => $table)));
    }

    $fixnull = FALSE;
    if (!empty($spec['not null']) && !isset($spec['default'])) {
      $fixnull = TRUE;
      $spec['not null'] = FALSE;
    }
    $query = 'ALTER TABLE {' . $table . '} ADD ';
    $query .= $this->createFieldSql($field, $this->processField($spec));
    if ($keys_sql = $this->createKeysSql($keys_new)) {
      $query .= ', ADD ' . implode(', ADD ', $keys_sql);
    }
    $this->connection->query($query);
    if (isset($spec['initial'])) {
      $this->connection->update($table)
        ->fields(array($field => $spec['initial']))
        ->execute();
    }
    if ($fixnull) {
      $spec['not null'] = TRUE;
      $this->changeField($table, $field, $field, $spec);
    }
  }

  public function dropField($table, $field) {
    if (!$this->fieldExists($table, $field)) {
      return FALSE;
    }

    $this->connection->query('ALTER TABLE {' . $table . '} DROP `' . $field . '`');
    return TRUE;
  }

  public function fieldSetDefault($table, $field, $default) {
    if (!$this->fieldExists($table, $field)) {
      throw new DatabaseSchemaObjectDoesNotExistException(t("Cannot set default value of field %table.%field: field doesn't exist.", array('%table' => $table, '%field' => $field)));
    }

    if (!isset($default)) {
      $default = 'NULL';
    }
    else {
      $default = is_string($default) ? "'$default'" : $default;
    }

    $this->connection->query('ALTER TABLE {' . $table . '} ALTER COLUMN `' . $field . '` SET DEFAULT ' . $default);
  }

  public function fieldSetNoDefault($table, $field) {
    if (!$this->fieldExists($table, $field)) {
      throw new DatabaseSchemaObjectDoesNotExistException(t("Cannot remove default value of field %table.%field: field doesn't exist.", array('%table' => $table, '%field' => $field)));
    }

    $this->connection->query('ALTER TABLE {' . $table . '} ALTER COLUMN `' . $field . '` DROP DEFAULT');
  }

  public function indexExists($table, $name) {
    // Returns one row for each column in the index. Result is string or FALSE.
    // Details at http://dev.mysql.com/doc/refman/5.0/en/show-index.html
    $row = $this->connection->query('SHOW INDEX FROM {' . $table . "} WHERE key_name = '$name'")->fetchAssoc();
    return isset($row['key_name']);
  }

  public function addPrimaryKey($table, $fields) {
    if (!$this->tableExists($table)) {
      throw new DatabaseSchemaObjectDoesNotExistException(t("Cannot add primary key to table %table: table doesn't exist.", array('%table' => $table)));
    }
    if ($this->indexExists($table, 'PRIMARY')) {
      throw new DatabaseSchemaObjectExistsException(t("Cannot add primary key to table %table: primary key already exists.", array('%table' => $table)));
    }

    $this->connection->query('ALTER TABLE {' . $table . '} ADD PRIMARY KEY (' . $this->createKeySql($fields) . ')');
  }

  public function dropPrimaryKey($table) {
    if (!$this->indexExists($table, 'PRIMARY')) {
      return FALSE;
    }

    $this->connection->query('ALTER TABLE {' . $table . '} DROP PRIMARY KEY');
    return TRUE;
  }

  public function addUniqueKey($table, $name, $fields) {
    if (!$this->tableExists($table)) {
      throw new DatabaseSchemaObjectDoesNotExistException(t("Cannot add unique key %name to table %table: table doesn't exist.", array('%table' => $table, '%name' => $name)));
    }
    if ($this->indexExists($table, $name)) {
      throw new DatabaseSchemaObjectExistsException(t("Cannot add unique key %name to table %table: unique key already exists.", array('%table' => $table, '%name' => $name)));
    }

    $this->connection->query('ALTER TABLE {' . $table . '} ADD UNIQUE KEY `' . $name . '` (' . $this->createKeySql($fields) . ')');
  }

  public function dropUniqueKey($table, $name) {
    if (!$this->indexExists($table, $name)) {
      return FALSE;
    }

    $this->connection->query('ALTER TABLE {' . $table . '} DROP KEY `' . $name . '`');
    return TRUE;
  }

  public function addIndex($table, $name, $fields) {
    if (!$this->tableExists($table)) {
      throw new DatabaseSchemaObjectDoesNotExistException(t("Cannot add index %name to table %table: table doesn't exist.", array('%table' => $table, '%name' => $name)));
    }
    if ($this->indexExists($table, $name)) {
      throw new DatabaseSchemaObjectExistsException(t("Cannot add index %name to table %table: index already exists.", array('%table' => $table, '%name' => $name)));
    }

    $this->connection->query('ALTER TABLE {' . $table . '} ADD INDEX `' . $name . '` (' . $this->createKeySql($fields) . ')');
  }

  public function dropIndex($table, $name) {
    if (!$this->indexExists($table, $name)) {
      return FALSE;
    }

    $this->connection->query('ALTER TABLE {' . $table . '} DROP INDEX `' . $name . '`');
    return TRUE;
  }

  public function changeField($table, $field, $field_new, $spec, $keys_new = array()) {
    if (!$this->fieldExists($table, $field)) {
      throw new DatabaseSchemaObjectDoesNotExistException(t("Cannot change the definition of field %table.%name: field doesn't exist.", array('%table' => $table, '%name' => $field)));
    }
    if (($field != $field_new) && $this->fieldExists($table, $field_new)) {
      throw new DatabaseSchemaObjectExistsException(t("Cannot rename field %table.%name to %name_new: target field already exists.", array('%table' => $table, '%name' => $field, '%name_new' => $field_new)));
    }

    $sql = 'ALTER TABLE {' . $table . '} CHANGE `' . $field . '` ' . $this->createFieldSql($field_new, $this->processField($spec));
    if ($keys_sql = $this->createKeysSql($keys_new)) {
      $sql .= ', ADD ' . implode(', ADD ', $keys_sql);
    }
    $this->connection->query($sql);
  }

  public function prepareComment($comment, $length = NULL) {
    // Work around a bug in some versions of PDO, see http://bugs.php.net/bug.php?id=41125
    $comment = str_replace("'", '’', $comment);

    // Truncate comment to maximum comment length.
    if (isset($length)) {
      // Add table prefixes before truncating.
      $comment = truncate_utf8($this->connection->prefixTables($comment), $length, TRUE, TRUE);
    }

    return $this->connection->quote($comment);
  }

  /**
   * Retrieve a table or column comment.
   */
  public function getComment($table, $column = NULL) {
    $condition = $this->buildTableNameCondition($table);
    if (isset($column)) {
      $condition->condition('column_name', $column);
      $condition->compile($this->connection, $this);
      // Don't use {} around information_schema.columns table.
      return $this->connection->query("SELECT column_comment FROM information_schema.columns WHERE " . (string) $condition, $condition->arguments())->fetchField();
    }
    $condition->compile($this->connection, $this);
    // Don't use {} around information_schema.tables table.
    $comment = $this->connection->query("SELECT table_comment FROM information_schema.tables WHERE " . (string) $condition, $condition->arguments())->fetchField();
    // Work-around for MySQL 5.0 bug http://bugs.mysql.com/bug.php?id=11379
    return preg_replace('/; InnoDB free:.*$/', '', $comment);
  }

  public function tableExists($table) {
    // The information_schema table is very slow to query under MySQL 5.0.
    // Instead, we try to select from the table in question.  If it fails,
    // the most likely reason is that it does not exist. That is dramatically
    // faster than using information_schema.
    // @link http://bugs.mysql.com/bug.php?id=19588
    // @todo: This override should be removed once we require a version of MySQL
    // that has that bug fixed.
    try {
      $this->connection->queryRange("SELECT 1 FROM {" . $table . "}", 0, 1);
      return TRUE;
    }
    catch (Exception $e) {
      return FALSE;
    }
  }

  public function fieldExists($table, $column) {
    // The information_schema table is very slow to query under MySQL 5.0.
    // Instead, we try to select from the table and field in question. If it
    // fails, the most likely reason is that it does not exist. That is
    // dramatically faster than using information_schema.
    // @link http://bugs.mysql.com/bug.php?id=19588
    // @todo: This override should be removed once we require a version of MySQL
    // that has that bug fixed.
    try {
      $this->connection->queryRange("SELECT $column FROM {" . $table . "}", 0, 1);
      return TRUE;
    }
    catch (Exception $e) {
      return FALSE;
    }
  }

}

/**
 * @} End of "ingroup schemaapi".
 */

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