lib/dataformatlib.php

   1 <?php
   2 // This file is part of Moodle - http://moodle.org/
   3 //
   4 // Moodle is free software: you can redistribute it and/or modify
   5 // it under the terms of the GNU General Public License as published by
   6 // the Free Software Foundation, either version 3 of the License, or
   7 // (at your option) any later version.
   8 //
   9 // Moodle is distributed in the hope that it will be useful,
  10 // but WITHOUT ANY WARRANTY; without even the implied warranty of
  11 // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  12 // GNU General Public License for more details.
  13 //
  14 // You should have received a copy of the GNU General Public License
  15 // along with Moodle.  If not, see <http://www.gnu.org/licenses/>.
  16
  17 /**
  18  * dataformatlib.php - Contains core dataformat related functions.
  19  *
  20  * @package    core
  21  * @subpackage dataformat
  22  * @copyright  2016 Brendan Heywood (brendan@catalyst-au.net)
  23  * @license    http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
  24  */
  25
  26 /**
  27  * Sends a formated data file to the browser
  28  *
  29  * @package    core
  30  * @subpackage dataformat
  31  *
  32  * @param string $filename The base filename without an extension
  33  * @param string $dataformat A dataformat name
  34  * @param array $columns An ordered map of column keys and labels
  35  * @param Iterator $iterator An iterator over the records, usually a RecordSet
  36  * @param function $callback An option function applied to each record before writing
  37  * @param mixed $extra An optional value which is passed into the callback function
  38  */
  39 function download_as_dataformat($filename, $dataformat, $columns, $iterator, $callback = null) {
  40
  41     if (ob_get_length()) {
  42         throw new coding_exception("Output can not be buffered before calling download_as_dataformat");
  43     }
  44
  45     $classname = 'dataformat_' . $dataformat . '\writer';
  46     if (!class_exists($classname)) {
  47         throw new coding_exception("Unable to locate dataformat/$dataformat/classes/writer.php");
  48     }
  49     $format = new $classname;
  50
  51     // The data format export could take a while to generate...
  52     set_time_limit(0);
  53
  54     // Close the session so that the users other tabs in the same session are not blocked.
  55     \core\session\manager::write_close();
  56
  57     $format->set_filename($filename);
  58     $format->send_http_headers();
  59     // This exists to support all dataformats - see MDL-56046.
  60     if (method_exists($format, 'write_header')) {
  61         error_log('The function write_header() does not support multiple sheets. In order to support multiple sheets you ' .
  62             'must implement start_output() and start_sheet() and remove write_header() in your dataformat.');
  63         $format->write_header($columns);
  64     } else {
  65         $format->start_output();
  66         $format->start_sheet($columns);
  67     }
  68     $c = 0;
  69     foreach ($iterator as $row) {
  70         if ($callback) {
  71             $row = $callback($row);
  72         }
  73         if ($row === null) {
  74             continue;
  75         }
  76         $format->write_record($row, $c++);
  77     }
  78     // This exists to support all dataformats - see MDL-56046.
  79     if (method_exists($format, 'write_footer')) {
  80         error_log('The function write_footer() does not support multiple sheets. In order to support multiple sheets you ' .
  81             'must implement close_sheet() and close_output() and remove write_footer() in your dataformat.');
  82         $format->write_footer($columns);
  83     } else {
  84         $format->close_sheet($columns);
  85         $format->close_output();
  86     }
  87 }
  88