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<?php
// This file is part of Moodle - http://moodle.org/
//
// Moodle is free software: you can redistribute it and/or modify
// it under the terms of the GNU General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.
//
// Moodle 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 General Public License for more details.
//
// You should have received a copy of the GNU General Public License
// along with Moodle. If not, see <http://www.gnu.org/licenses/>.
/**
* General database importer class
*
* @package core_dtl
* @copyright 2008 Andrei Bautu
* @license http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
*/
defined('MOODLE_INTERNAL') || die();
/**
* Base class for database import operations. This class implements
* basic callbacks for import operations and defines the @see import_database
* method as a common method for all importers. In general, subclasses will
* override import_database and call other methods in appropriate moments.
* Between a single pair of calls to @see begin_database_import and
* @see finish_database_import, multiple non-overlapping pairs of calls may
* be made to @see begin_table_import and @see finish_database_import for
* different tables.
* Between one pair of calls to @see begin_table_import and
* @see finish_database_import multiple calls may be made to
* @see import_table_data for the same table.
* This class can be used directly, if the standard control flow (defined above)
* is respected.
*/
class database_importer {
/** @var moodle_database Connection to the target database (a @see moodle_database object). */
protected $mdb;
/** @var database_manager Database manager of the target database (a @see database_manager object). */
protected $manager;
/** @var xmldb_structure Target database schema in XMLDB format (a @see xmldb_structure object). */
protected $schema;
/**
* Boolean flag - whether or not to check that XML database schema matches
* the RDBMS database schema before importing (used by
* @see begin_database_import).
* @var bool
*/
protected $check_schema;
/** @var string How to use transactions. */
protected $transactionmode = 'allinone';
/** @var moodle_transaction Transaction object */
protected $transaction;
/**
* Object constructor.
*
* @param moodle_database $mdb Connection to the target database (a
* @see moodle_database object). Use null to use the current $DB connection.
* @param boolean $check_schema - whether or not to check that XML database
* schema matches the RDBMS database schema before importing (inside
* @see begin_database_import).
*/
public function __construct(moodle_database $mdb, $check_schema=true) {
$this->mdb = $mdb;
$this->manager = $mdb->get_manager();
$this->schema = $this->manager->get_install_xml_schema();
$this->check_schema = $check_schema;
}
/**
* How to use transactions during the import.
* @param string $mode 'pertable', 'allinone' or 'none'.
*/
public function set_transaction_mode($mode) {
if (!in_array($mode, array('pertable', 'allinone', 'none'))) {
throw new coding_exception('Unknown transaction mode', $mode);
}
$this->transactionmode = $mode;
}
/**
* Callback function. Should be called only once database per import
* operation, before any database changes are made. It will check the database
* schema if @see check_schema is true
*
* @throws dbtransfer_exception if any checking (e.g. database schema, Moodle
* version) fails
*
* @param float $version the version of the system which generated the data
* @param string $timestamp the timestamp of the data (in ISO 8601) format.
* @return void
*/
public function begin_database_import($version, $timestamp) {
global $CFG;
if (!$this->mdb->get_tables()) {
// No tables present yet, time to create all tables.
$this->manager->install_from_xmldb_structure($this->schema);
}
if (round($version, 2) !== round($CFG->version, 2)) { // version might be in decimal format too
$a = (object)array('schemaver'=>$version, 'currentver'=>$CFG->version);
throw new dbtransfer_exception('importversionmismatchexception', $a);
}
$options = [
'changedcolumns' => false, // Column types may be fixed by transfer.
'missingindexes' => false // No need to worry about indexes for transfering data.
];
if ($this->check_schema and $errors = $this->manager->check_database_schema($this->schema, $options)) {
$details = '';
foreach ($errors as $table=>$items) {
$details .= '<div>'.get_string('table').' '.$table.':';
$details .= '<ul>';
foreach ($items as $item) {
$details .= '<li>'.$item.'</li>';
}
$details .= '</ul></div>';
}
throw new dbtransfer_exception('importschemaexception', $details);
}
if ($this->transactionmode == 'allinone') {
$this->transaction = $this->mdb->start_delegated_transaction();
}
}
/**
* Callback function. Should be called only once per table import operation,
* before any table changes are made. It will delete all table data.
*
* @throws dbtransfer_exception an unknown table import is attempted
* @throws ddl_table_missing_exception if the table is missing
*
* @param string $tablename - the name of the table that will be imported
* @param string $schemaHash - the hash of the xmldb_table schema of the table
* @return void
*/
public function begin_table_import($tablename, $schemaHash) {
if ($this->transactionmode == 'pertable') {
$this->transaction = $this->mdb->start_delegated_transaction();
}
if (!$table = $this->schema->getTable($tablename)) {
throw new dbtransfer_exception('unknowntableexception', $tablename);
}
if ($schemaHash != $table->getHash()) {
throw new dbtransfer_exception('differenttableexception', $tablename);
}
// this should not happen, unless someone drops tables after import started
if (!$this->manager->table_exists($table)) {
throw new ddl_table_missing_exception($tablename);
}
$this->mdb->delete_records($tablename);
}
/**
* Callback function. Should be called only once per table import operation,
* after all table changes are made. It will reset table sequences if any.
* @param string $tablename
* @return void
*/
public function finish_table_import($tablename) {
$table = $this->schema->getTable($tablename);
$fields = $table->getFields();
foreach ($fields as $field) {
if ($field->getSequence()) {
$this->manager->reset_sequence($tablename);
return;
}
}
if ($this->transactionmode == 'pertable') {
$this->transaction->allow_commit();
}
}
/**
* Callback function. Should be called only once database per import
* operation, after all database changes are made. It will commit changes.
* @return void
*/
public function finish_database_import() {
if ($this->transactionmode == 'allinone') {
$this->transaction->allow_commit();
}
}
/**
* Callback function. Should be called only once per record import operation, only
* between @see begin_table_import and @see finish_table_import calls.
* It will insert table data.
*
* @throws dml_exception if data insert operation failed
*
* @param string $tablename - the name of the table in which data will be
* imported
* @param object $data - data object (fields and values will be inserted
* into table)
* @return void
*/
public function import_table_data($tablename, $data) {
$this->mdb->import_record($tablename, $data);
}
/**
* Common import method
* @return void
*/
public function import_database() {
// implement in subclasses
}
}