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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/>.
/**
* Helpers and methods relating to DML tables.
*
* @since Moodle 3.7
* @package core
* @category dml
* @copyright 2019 Andrew Nicols <andrew@nicols.co.uk>
* @license http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
*/
namespace core\dml;
use stdClass;
defined('MOODLE_INTERNAL') || die();
/**
* Helpers and methods relating to DML tables.
*
* @copyright 2019 Andrew Nicols <andrew@nicols.co.uk>
* @license http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
*/
class table {
/** @var string Name of the table that this class represents */
protected $tablename;
/** @var string Table alias */
protected $tablealias;
/** @var string Prefix to place before each field */
protected $fieldprefix;
/** @var array List of fields */
protected $fields;
/**
* Constructor for the table class.
*
* @param string $tablename The name of the table that this instance represents.
* @param string $tablealias The alias to use when selecting the table
* @param string $fieldprefix The prefix to use when selecting fields.
*/
public function __construct(string $tablename, string $tablealias, string $fieldprefix) {
$this->tablename = $tablename;
$this->tablealias = $tablealias;
$this->fieldprefix = $fieldprefix;
}
/**
* Get the from TABLE ALIAS part of the FROM/JOIN string.
*
* @return string
*/
public function get_from_sql() : string {
return "{{$this->tablename}} {$this->tablealias}";
}
/**
* Get the list of fields in a table for use in preloading fields.
*
* @return array The list of columns in a table. The array key is the column name with an applied prefix.
*/
protected function get_fieldlist() : array {
global $DB;
if (null === $this->fields) {
$fields = [];
foreach (array_keys($DB->get_columns($this->tablename)) as $fieldname) {
$fields["{$this->fieldprefix}{$fieldname}"] = $fieldname;
}
$this->fields = $fields;
}
return $this->fields;
}
/**
* Get the SELECT SQL to select a set of columns for this table.
*
* This function is intended to be used in combination with extract_from_result().
*
* @return string The SQL to use in the SELECT
*/
public function get_field_select() : string {
$fieldlist = $this->get_fieldlist();
return implode(', ', array_map(function($fieldname, $fieldalias) {
return "{$this->tablealias}.{$fieldname} AS {$fieldalias}";
}, $fieldlist, array_keys($fieldlist)));
}
/**
* Extract fields from the specified result. The fields are removed from the original object.
*
* This function is intended to be used in combination with get_field_select().
*
* @param stdClass $result The result retrieved from the database with fields to be extracted
* @return stdClass The extracted result
*/
public function extract_from_result(stdClass $result) : stdClass {
$record = new stdClass();
$fieldlist = $this->get_fieldlist();
foreach ($fieldlist as $fieldalias => $fieldname) {
if (property_exists($result, $fieldalias)) {
$record->$fieldname = $result->$fieldalias;
unset($result->$fieldalias);
} else {
debugging("Field '{$fieldname}' not found", DEBUG_DEVELOPER);
}
}
return $record;
}
}