MDL-71685 dataformat_json: include column names in exported file.

dataformat/json/classes/writer.php

@@ -24,7 +24,7 @@
 
 namespace dataformat_json;
 
-defined('MOODLE_INTERNAL') || die();
+use core_text;
 
 /**
  * JSON data format writer
@@ -47,6 +47,9 @@ class writer extends \core\dataformat\base {
     /** @var $sheetdatadded */
     public $sheetdatadded = false;
 
+    /** @var string[] $columns */
+    protected $columns = [];
+
     /**
      * Write the start of the file.
      */
@@ -60,6 +63,10 @@ public function start_output() {
      * @param array $columns
      */
     public function start_sheet($columns) {
+        $this->columns = array_map(function($column) {
+            return core_text::strtolower(clean_param($column, PARAM_ALPHA));
+        }, $columns);
+
         if ($this->sheetstarted) {
             echo ",";
         } else {
@@ -80,6 +87,8 @@ public function write_record($record, $rownum) {
             echo ",";
         }
 
+        // Ensure our record is keyed by column names, rather than numerically.
+        $record = array_combine($this->columns, (array) $record);
         echo json_encode($this->format_record($record), JSON_UNESCAPED_UNICODE | JSON_PRETTY_PRINT);
 
         $this->sheetdatadded = true;