mirror of
https://github.com/moodle/moodle.git
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2be4d090c0
Even though I've tweaked this and done some polishing, there is still plenty to do on it now in HEAD, mostly to do with UI, usability and strings, so we'll keep working on it. Aaron already has a number of improvements to add to it.
314 lines
11 KiB
PHP
314 lines
11 KiB
PHP
<?php
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///////////////////////////////////////////////////////////////////////////
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// //
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// NOTICE OF COPYRIGHT //
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// //
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// Moodle - Modular Object-Oriented Dynamic Learning Environment //
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// http://moodle.com //
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// //
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// Copyright (C) 1999 onwards Martin Dougiamas http://dougiamas.com //
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// //
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// This program is free software; you can redistribute it and/or modify //
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// it under the terms of the GNU General Public License as published by //
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// the Free Software Foundation; either version 2 of the License, or //
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// (at your option) any later version. //
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// //
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// This program is distributed in the hope that it will be useful, //
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// but WITHOUT ANY WARRANTY; without even the implied warranty of //
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// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the //
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// GNU General Public License for more details: //
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// //
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// http://www.gnu.org/copyleft/gpl.html //
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// //
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///////////////////////////////////////////////////////////////////////////
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/**
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* A data abstraction object that holds methods and attributes
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* @abstract
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*/
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abstract class data_object {
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/**
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* Table that the class maps to in the database
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* @var string $table
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*/
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public $table;
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/**
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* Array of required table fields, must start with 'id'.
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* @var array $required_fields
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*/
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public $required_fields = array('id');
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/**
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* Array of optional fields with default values - usually long text information that is not always needed.
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* If you want to create an instance without optional fields use: new data_object($only_required_fields, false);
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* @var array $optional_fields
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*/
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public $optional_fields = array();
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/**
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* The PK.
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* @var int $id
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*/
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public $id;
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/**
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* Constructor. Optionally (and by default) attempts to fetch corresponding row from DB.
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* @param array $params an array with required parameters for this data object.
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* @param boolean $fetch Whether to fetch corresponding row from DB or not,
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* optional fields might not be defined if false used
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*/
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public function __construct($params=NULL, $fetch=true) {
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if (!empty($params) and (is_array($params) or is_object($params))) {
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if ($fetch) {
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if ($data = $this->fetch($params)) {
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self::set_properties($this, $data);
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} else {
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self::set_properties($this, $this->optional_fields);//apply defaults for optional fields
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self::set_properties($this, $params);
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}
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} else {
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self::set_properties($this, $params);
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}
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} else {
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self::set_properties($this, $this->optional_fields);//apply defaults for optional fields
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}
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}
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/**
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* Makes sure all the optional fields are loaded.
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* If id present (==instance exists in db) fetches data from db.
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* Defaults are used for new instances.
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*/
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public function load_optional_fields() {
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global $DB;
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foreach ($this->optional_fields as $field=>$default) {
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if (array_key_exists($field, $this)) {
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continue;
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}
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if (empty($this->id)) {
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$this->$field = $default;
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} else {
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$this->$field = $DB->get_field($this->table, $field, array('id', $this->id));
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}
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}
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}
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/**
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* Finds and returns a data_object instance based on params.
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* @static abstract
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*
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* @param array $params associative arrays varname=>value
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* @return object data_object instance or false if none found.
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*/
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public static abstract function fetch($params);
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/**
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* Finds and returns all data_object instances based on params.
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*
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* @param array $params associative arrays varname=>value
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* @return array array of data_object insatnces or false if none found.
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*/
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public static function fetch_all($params) {}
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/**
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* Factory method - uses the parameters to retrieve matching instance from the DB.
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* @static final protected
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* @return mixed object instance or false if not found
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*/
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protected static function fetch_helper($table, $classname, $params) {
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if ($instances = self::fetch_all_helper($table, $classname, $params)) {
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if (count($instances) > 1) {
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// we should not tolerate any errors here - problems might appear later
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print_error('morethanonerecordinfetch','debug');
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}
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return reset($instances);
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} else {
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return false;
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}
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}
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/**
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* Factory method - uses the parameters to retrieve all matching instances from the DB.
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* @static final protected
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* @return mixed array of object instances or false if not found
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*/
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public static function fetch_all_helper($table, $classname, $params) {
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$instance = new $classname();
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$classvars = (array)$instance;
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$params = (array)$params;
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$wheresql = array();
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foreach ($params as $var=>$value) {
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if (!in_array($var, $instance->required_fields) and !array_key_exists($var, $instance->optional_fields)) {
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continue;
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}
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if (is_null($value)) {
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$wheresql[] = " $var IS NULL ";
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} else {
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$wheresql[] = " $var = ? ";
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$params[] = $value;
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}
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}
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if (empty($wheresql)) {
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$wheresql = '';
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} else {
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$wheresql = implode("AND", $wheresql);
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}
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global $DB;
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if ($datas = $DB->get_records_select($table, $wheresql, $params)) {
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$result = array();
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foreach($datas as $data) {
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$instance = new $classname();
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self::set_properties($instance, $data);
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$result[$instance->id] = $instance;
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}
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return $result;
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} else {
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return false;
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}
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}
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/**
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* Updates this object in the Database, based on its object variables. ID must be set.
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* @return boolean success
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*/
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public function update() {
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global $DB;
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if (empty($this->id)) {
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debugging('Can not update data object, no id!');
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return false;
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}
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$data = $this->get_record_data();
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$DB->update_record($this->table, $data);
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$this->notify_changed(false);
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return true;
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}
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/**
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* Deletes this object from the database.
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* @return boolean success
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*/
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public function delete() {
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global $DB;
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if (empty($this->id)) {
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debugging('Can not delete data object, no id!');
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return false;
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}
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$data = $this->get_record_data();
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if ($DB->delete_records($this->table, array('id'=>$this->id))) {
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$this->notify_changed(true);
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return true;
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} else {
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return false;
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}
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}
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/**
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* Returns object with fields and values that are defined in database
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*/
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public function get_record_data() {
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$data = new object();
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foreach ($this as $var=>$value) {
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if (in_array($var, $this->required_fields) or array_key_exists($var, $this->optional_fields)) {
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if (is_object($value) or is_array($value)) {
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debugging("Incorrect property '$var' found when inserting data object");
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} else {
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$data->$var = $value;
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}
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}
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}
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return $data;
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}
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/**
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* Records this object in the Database, sets its id to the returned value, and returns that value.
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* If successful this function also fetches the new object data from database and stores it
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* in object properties.
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* @return int PK ID if successful, false otherwise
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*/
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public function insert() {
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global $DB;
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if (!empty($this->id)) {
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debugging("Data object already exists!");
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return false;
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}
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$data = $this->get_record_data();
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$this->id = $DB->insert_record($this->table, $data);
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// set all object properties from real db data
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$this->update_from_db();
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$this->notify_changed(false);
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return $this->id;
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}
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/**
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* Using this object's id field, fetches the matching record in the DB, and looks at
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* each variable in turn. If the DB has different data, the db's data is used to update
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* the object. This is different from the update() function, which acts on the DB record
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* based on the object.
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*/
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public function update_from_db() {
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if (empty($this->id)) {
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debugging("The object could not be used in its state to retrieve a matching record from the DB, because its id field is not set.");
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return false;
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}
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global $DB;
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if (!$params = $DB->get_record($this->table, array('id' => $this->id))) {
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debugging("Object with this id:{$this->id} does not exist in table:{$this->table}, can not update from db!");
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return false;
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}
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self::set_properties($this, $params);
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return true;
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}
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/**
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* Given an associated array or object, cycles through each key/variable
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* and assigns the value to the corresponding variable in this object.
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* @static final
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*/
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public static function set_properties(&$instance, $params) {
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$params = (array) $params;
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foreach ($params as $var => $value) {
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if (in_array($var, $instance->required_fields) or array_key_exists($var, $instance->optional_fields)) {
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$instance->$var = $value;
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}
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}
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}
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/**
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* Called immediately after the object data has been inserted, updated, or
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* deleted in the database. Default does nothing, can be overridden to
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* hook in special behaviour.
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*
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* @param bool $deleted
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*/
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function notify_changed($deleted) {
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}
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}
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