class.timestampvalidator.php

<?php
/**
 * @package toolkit
 */

/**
 * This class checks against the Database for the latest timestamp, to make
 * sure the data being saved is the one the user saw.
 *
 * @since Symphony 2.7.0
 */

class TimestampValidator
{
    /**
     * The name of the table to check against
     * @var string
     */
    private $table = '';

    /**
     * Creates a new TimestampValidator object, for a particular table.
     * The `tbl_` prefix is automatically added.
     *
     * @param string $table
     *   The table name
     */
    public function __construct($table)
    {
        General::ensureType(array(
            'table' => array('var' => $table, 'type'=> 'string'),
        ));
        $this->table = 'tbl_' . MySQL::cleanValue($table);
    }

    /**
     * Checks if the modified date of the record identified with $id
     * if equal to the supplied $timestamp
     *
     * @param int|string $id
     *  The record id to check
     * @param string $timestamp
     *  The user supplied timestamp
     * @return boolean
     *  true if the $timestamp is the latest or the $id is invalid, false other wise
     */
    public function check($id, $timestamp)
    {
        $id = General::intval(MySQL::cleanValue($id));
        if ($id < 1) {
            return false;
        }
        $timestamp = MySQL::cleanValue($timestamp);
        $sql = "
            SELECT `id` FROM `{$this->table}`
                WHERE `id` = $id
                    AND `modification_date` = '$timestamp'
        ";
        $results = Symphony::Database()->fetchVar('id', 0, $sql);
        return !empty($results) && General::intval($results) === $id;
    }
}