lib/dtl/database_importer.php

   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 importer 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 import operations. This class implements
  29  * basic callbacks for import operations and defines the @see import_database
  30  * method as a common method for all importers. In general, subclasses will
  31  * override import_database and call other methods in appropriate moments.
  32  * Between a single pair of calls to @see begin_database_import and
  33  * @see finish_database_import, multiple non-overlapping pairs of calls may
  34  * be made to @see begin_table_import and @see finish_database_import for
  35  * different tables.
  36  * Between one pair of calls to @see begin_table_import and
  37  * @see finish_database_import multiple calls may be made to
  38  * @see import_table_data for the same table.
  39  * This class can be used directly, if the standard control flow (defined above)
  40  * is respected.
  41  */
  42 class database_importer {
  43     /** @var moodle_database Connection to the target database (a @see moodle_database object). */
  44     protected $mdb;
  45     /** @var database_manager Database manager of the target database (a @see database_manager object). */
  46     protected $manager;
  47     /** @var xmldb_structure Target database schema in XMLDB format (a @see xmldb_structure object). */
  48     protected $schema;
  49     /**
  50      * Boolean flag - whether or not to check that XML database schema matches
  51      * the RDBMS database schema before importing (used by
  52      * @see begin_database_import).
  53      * @var bool
  54      */
  55     protected $check_schema;
  56     /** @var string How to use transactions. */
  57     protected $transactionmode = 'allinone';
  58     /** @var moodle_transaction Transaction object */
  59     protected $transaction;
  60
  61     /**
  62      * Object constructor.
  63      *
  64      * @param moodle_database $mdb Connection to the target database (a
  65      * @see moodle_database object). Use null to use the current $DB connection.
  66      * @param boolean $check_schema - whether or not to check that XML database
  67      * schema matches the RDBMS database schema before importing (inside
  68      * @see begin_database_import).
  69      */
  70     public function __construct(moodle_database $mdb, $check_schema=true) {
  71         $this->mdb          = $mdb;
  72         $this->manager      = $mdb->get_manager();
  73         $this->schema       = $this->manager->get_install_xml_schema();
  74         $this->check_schema = $check_schema;
  75     }
  76
  77     /**
  78      * How to use transactions during the import.
  79      * @param string $mode 'pertable', 'allinone' or 'none'.
  80      */
  81     public function set_transaction_mode($mode) {
  82         if (!in_array($mode, array('pertable', 'allinone', 'none'))) {
  83             throw new coding_exception('Unknown transaction mode', $mode);
  84         }
  85         $this->transactionmode = $mode;
  86     }
  87
  88     /**
  89      * Callback function. Should be called only once database per import
  90      * operation, before any database changes are made. It will check the database
  91      * schema if @see check_schema is true
  92      *
  93      * @throws dbtransfer_exception if any checking (e.g. database schema, Moodle
  94      * version) fails
  95      *
  96      * @param float $version the version of the system which generated the data
  97      * @param string $timestamp the timestamp of the data (in ISO 8601) format.
  98      * @return void
  99      */
 100     public function begin_database_import($version, $timestamp) {
 101         global $CFG;
 102
 103         if (!$this->mdb->get_tables()) {
 104             // No tables present yet, time to create all tables.
 105             $this->manager->install_from_xmldb_structure($this->schema);
 106         }
 107
 108         if (round($version, 2) !== round($CFG->version, 2)) { // version might be in decimal format too
 109             $a = (object)array('schemaver'=>$version, 'currentver'=>$CFG->version);
 110             throw new dbtransfer_exception('importversionmismatchexception', $a);
 111         }
 112
 113         $options = array('changedcolumns' => false); // Column types may be fixed by transfer.
 114         if ($this->check_schema and $errors = $this->manager->check_database_schema($this->schema, $options)) {
 115             $details = '';
 116             foreach ($errors as $table=>$items) {
 117                 $details .= '<div>'.get_string('table').' '.$table.':';
 118                 $details .= '<ul>';
 119                 foreach ($items as $item) {
 120                     $details .= '<li>'.$item.'</li>';
 121                 }
 122                 $details .= '</ul></div>';
 123             }
 124             throw new dbtransfer_exception('importschemaexception', $details);
 125         }
 126         if ($this->transactionmode == 'allinone') {
 127             $this->transaction = $this->mdb->start_delegated_transaction();
 128         }
 129     }
 130
 131     /**
 132      * Callback function. Should be called only once per table import operation,
 133      * before any table changes are made. It will delete all table data.
 134      *
 135      * @throws dbtransfer_exception an unknown table import is attempted
 136      * @throws ddl_table_missing_exception if the table is missing
 137      *
 138      * @param string $tablename - the name of the table that will be imported
 139      * @param string $schemaHash - the hash of the xmldb_table schema of the table
 140      * @return void
 141      */
 142     public function begin_table_import($tablename, $schemaHash) {
 143         if ($this->transactionmode == 'pertable') {
 144             $this->transaction = $this->mdb->start_delegated_transaction();
 145         }
 146         if (!$table = $this->schema->getTable($tablename)) {
 147             throw new dbtransfer_exception('unknowntableexception', $tablename);
 148         }
 149         if ($schemaHash != $table->getHash()) {
 150             throw new dbtransfer_exception('differenttableexception', $tablename);
 151         }
 152         // this should not happen, unless someone drops tables after import started
 153         if (!$this->manager->table_exists($table)) {
 154             throw new ddl_table_missing_exception($tablename);
 155         }
 156         $this->mdb->delete_records($tablename);
 157     }
 158
 159     /**
 160      * Callback function. Should be called only once per table import operation,
 161      * after all table changes are made. It will reset table sequences if any.
 162      * @param string $tablename
 163      * @return void
 164      */
 165     public function finish_table_import($tablename) {
 166         $table  = $this->schema->getTable($tablename);
 167         $fields = $table->getFields();
 168         foreach ($fields as $field) {
 169             if ($field->getSequence()) {
 170                 $this->manager->reset_sequence($tablename);
 171                 return;
 172             }
 173         }
 174         if ($this->transactionmode == 'pertable') {
 175             $this->transaction->allow_commit();
 176         }
 177     }
 178
 179     /**
 180      * Callback function. Should be called only once database per import
 181      * operation, after all database changes are made. It will commit changes.
 182      * @return void
 183      */
 184     public function finish_database_import() {
 185         if ($this->transactionmode == 'allinone') {
 186             $this->transaction->allow_commit();
 187         }
 188     }
 189
 190     /**
 191      * Callback function. Should be called only once per record import operation, only
 192      * between @see begin_table_import and @see finish_table_import calls.
 193      * It will insert table data.
 194      *
 195      * @throws dml_exception if data insert operation failed
 196      *
 197      * @param string $tablename - the name of the table in which data will be
 198      * imported
 199      * @param object $data - data object (fields and values will be inserted
 200      * into table)
 201      * @return void
 202      */
 203     public function import_table_data($tablename, $data) {
 204         $this->mdb->import_record($tablename, $data);
 205     }
 206
 207     /**
 208      * Common import method
 209      * @return void
 210      */
 211     public function import_database() {
 212         // implement in subclasses
 213     }
 214 }