Paul Holden
5ec86bf501
The group concatenation types now consistently sort the returned values and support aggregating columns containing multiple fields and those with defined callbacks.
118 lines
3.8 KiB
PHP
118 lines
3.8 KiB
PHP
<?php
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// This file is part of Moodle - http://moodle.org/
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//
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// Moodle 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 3 of the License, or
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// (at your option) any later version.
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//
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// Moodle 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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// You should have received a copy of the GNU General Public License
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// along with Moodle. If not, see <http://www.gnu.org/licenses/>.
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declare(strict_types=1);
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namespace core_reportbuilder\local\helpers;
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use coding_exception;
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use core_text;
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/**
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* Helper functions for DB manipulations
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*
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* @package core_reportbuilder
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* @copyright 2019 Marina Glancy
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* @license http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
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*/
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class database {
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/** @var string Prefix for generated aliases */
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private const GENERATE_ALIAS_PREFIX = 'rbalias';
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/** @var string Prefix for generated param names names */
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private const GENERATE_PARAM_PREFIX = 'rbparam';
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/**
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* Generates unique table/column alias that must be used in generated SQL
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*
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* @return string
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*/
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public static function generate_alias(): string {
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static $aliascount = 0;
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return static::GENERATE_ALIAS_PREFIX . ($aliascount++);
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}
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/**
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* Generates unique parameter name that must be used in generated SQL
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*
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* @return string
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*/
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public static function generate_param_name(): string {
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static $paramcount = 0;
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return static::GENERATE_PARAM_PREFIX . ($paramcount++);
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}
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/**
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* Validate that parameter names were generated using {@see generate_param_name}.
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*
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* @param array $params
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* @return bool
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* @throws coding_exception For invalid params.
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*/
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public static function validate_params(array $params): bool {
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$nonmatchingkeys = array_filter($params, static function($key): bool {
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return !preg_match('/^' . static::GENERATE_PARAM_PREFIX . '[\d]+/', $key);
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}, ARRAY_FILTER_USE_KEY);
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if (!empty($nonmatchingkeys)) {
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throw new coding_exception('Invalid parameter names', implode(', ', array_keys($nonmatchingkeys)));
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}
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return true;
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}
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/**
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* Generate SQL expression for sorting group concatenated fields
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*
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* @param string $field The original field or SQL expression
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* @param string|null $sort A valid SQL ORDER BY to sort the concatenated fields, if omitted then $field will be used
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* @return string
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*/
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public static function sql_group_concat_sort(string $field, string $sort = null): string {
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global $DB;
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// Fallback to sorting by the specified field, unless it contains parameters which would be duplicated.
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if ($sort === null && !preg_match('/[:?$]/', $field)) {
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$fieldsort = $field;
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} else {
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$fieldsort = $sort;
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}
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// Nothing to sort by.
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if ($fieldsort === null) {
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return '';
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}
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// If the sort specifies a direction, we need to handle that differently in Postgres.
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if ($DB->get_dbfamily() === 'postgres') {
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$fieldsortdirection = '';
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preg_match('/(?<direction>ASC|DESC)?$/i', $fieldsort, $matches);
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if (array_key_exists('direction', $matches)) {
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$fieldsortdirection = $matches['direction'];
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$fieldsort = core_text::substr($fieldsort, 0, -(core_text::strlen($fieldsortdirection)));
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}
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// Cast sort, stick the direction on the end.
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$fieldsort = "CAST({$fieldsort} AS VARCHAR) {$fieldsortdirection}";
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}
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return $fieldsort;
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}
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}
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