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   1  <?php
   2  // This file is part of Moodle - http://moodle.org/
   3  //
   4  // Moodle is free software: you can redistribute it and/or modify
   5  // it under the terms of the GNU General Public License as published by
   6  // the Free Software Foundation, either version 3 of the License, or
   7  // (at your option) any later version.
   8  //
   9  // Moodle is distributed in the hope that it will be useful,
  10  // but WITHOUT ANY WARRANTY; without even the implied warranty of
  11  // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  12  // GNU General Public License for more details.
  13  //
  14  // You should have received a copy of the GNU General Public License
  15  // along with Moodle.  If not, see <http://www.gnu.org/licenses/>.
  16  
  17  /**
  18   * General database export class
  19   *
  20   * @package    core_dtl
  21   * @copyright  2008 Andrei Bautu
  22   * @license    http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
  23   */
  24  
  25  defined('MOODLE_INTERNAL') || die();
  26  
  27  /**
  28   * Base class for database export operations. This class defines basic callbacks
  29   * for export operations and implements the @see export_database and
  30   * @export_table methods generic export processing. In general, subclasses will
  31   * override callback methods to provide specific output and (optionally)
  32   * @see export_database to add functionality.
  33   * Between a single pair of calls to @see begin_database_export and
  34   * @see finish_database_export, multiple non-overlapping pairs of calls may
  35   * be made to @see begin_table_export and @see finish_database_export for
  36   * different tables. Between one pair of calls to @see begin_table_export and
  37   * @see finish_database_export multiple calls may be made to
  38   * @see export_table_data for the same table.
  39   */
  40  abstract class database_exporter {
  41      /** @var moodle_database Connection to the source database (a @see moodle_database object). */
  42      protected $mdb;
  43      /** @var database_manager Database manager of the source database (a @see database_manager object). */
  44      protected $manager;
  45      /** @var xmldb_structure Source database schema in XMLDB format (a @see xmldb_structure object). */
  46      protected $schema;
  47      /**
  48       * Boolean flag - whether or not to check that XML database schema matches
  49       * the RDBMS database schema before exporting (used by
  50       * @see export_database).
  51       * @var bool
  52       */
  53      protected $check_schema;
  54  
  55      /**
  56       * Object constructor.
  57       *
  58       * @param moodle_database $mdb Connection to the source database (a
  59       * @see moodle_database object).
  60       * @param boolean $check_schema - whether or not to check that XML database
  61       * schema matches the RDBMS database schema before exporting (used by
  62       * @see export_database).
  63       */
  64      public function __construct(moodle_database $mdb, $check_schema=true) {
  65          $this->mdb          = $mdb;
  66          $this->manager      = $mdb->get_manager();
  67          $this->schema       = $this->manager->get_install_xml_schema();
  68          $this->check_schema = $check_schema;
  69      }
  70  
  71      /**
  72       * Callback function. Should be called only once database per export
  73       * operation, before any other export operations. Subclasses should export
  74       * basic database information (version and timestamp).
  75       *
  76       * @param float $version the version of the system which generating the data
  77       * @param string $release moodle release info
  78       * @param string $timestamp the timestamp of the data (in ISO 8601) format.
  79       * @param string $description a user description of the data.
  80       * @return void
  81       */
  82      public abstract function begin_database_export($version, $release, $timestamp, $description);
  83  
  84      /**
  85       * Callback function. Should be called only once per table export operation,
  86       * before any other table export operations. Subclasses should export
  87       * basic database information (name and schema's hash).
  88       *
  89       * @param xmldb_table $table - XMLDB object for the exported table
  90       * @return void
  91       */
  92      public abstract function begin_table_export(xmldb_table $table);
  93  
  94      /**
  95       * Callback function. Should be called only once per table export operation,
  96       * after all other table export operations.
  97       *
  98       * @param xmldb_table $table - XMLDB object for the exported table
  99       */
 100      public abstract function finish_table_export(xmldb_table $table);
 101  
 102      /**
 103       * Callback function. Should be called only once database per export
 104       * operation, after all database export operations.
 105       */
 106      public abstract function finish_database_export();
 107  
 108      /**
 109       * Callback function. Should be called only once per record export operation,
 110       * only between @see begin_table_export and @see finish_table_export calls.
 111       * It will insert table data. Subclasses should export basic record
 112       * information (data values).
 113       *
 114       * @param xmldb_table $table - XMLDB object of the table from which data was retrieved
 115       * @param object $data - data object (fields and values from record)
 116       * @return void
 117       */
 118      public abstract function export_table_data(xmldb_table $table, $data);
 119  
 120      /**
 121       * Generic method to export the database. It checks the schema (if
 122       * @see $check_schema is true), queries the database and calls
 123       * appropriate callbacks.
 124       *
 125       * @throws dbtransfer_exception if any checking (e.g. database schema) fails
 126       *
 127       * @param string $description a user description of the data.
 128       */
 129      public function export_database($description=null) {
 130          global $CFG;
 131  
 132          $options = [
 133              'changedcolumns' => false, // Column types may be fixed by transfer.
 134              'missingindexes' => false, // No need to worry about indexes for transfering data.
 135              'extraindexes' => false
 136          ];
 137          if ($this->check_schema and $errors = $this->manager->check_database_schema($this->schema, $options)) {
 138              $details = '';
 139              foreach ($errors as $table=>$items) {
 140                  $details .= '<div>'.get_string('tablex', 'dbtransfer', $table);
 141                  $details .= '<ul>';
 142                  foreach ($items as $item) {
 143                      $details .= '<li>'.$item.'</li>';
 144                  }
 145                  $details .= '</ul></div>';
 146              }
 147              throw new dbtransfer_exception('exportschemaexception', $details);
 148          }
 149          $tables = $this->schema->getTables();
 150          $this->begin_database_export($CFG->version, $CFG->release, date('c'), $description);
 151          foreach ($tables as $table) {
 152              $rs = $this->mdb->export_table_recordset($table->getName());
 153              if (!$rs) {
 154                  throw new ddl_table_missing_exception($table->getName());
 155              }
 156              $this->begin_table_export($table);
 157              foreach ($rs as $row) {
 158                  $this->export_table_data($table, $row);
 159              }
 160              $this->finish_table_export($table);
 161              $rs->close();
 162          }
 163          $this->finish_database_export();
 164      }
 165  }