Added running id to csv export (if wanted).

Closes #3

app/Http/Controllers/ResultController.php

@@ -121,9 +121,13 @@ class ResultController extends Controller
 
         $all_rows = collect();
 
+        $id = config('experiment.csv-id-header-start');
+        $id_format = config('experiment.csv-id-header-format');
+        $id_header = config('experiment.csv-id-header');
+
         foreach ($results as $result) {
             $rows = collect($result->data ?? [])
-                ->map(function($row) use ($header) {
+                ->map(function($row) use ($header, $id_header, $id_format, $id) {
                     foreach ($header as $key) {
                         // Fill empty columns with N/A
                         $row[$key] = $row[$key] ?? config('experiment.n-a-text');
@@ -133,10 +137,20 @@ class ResultController extends Controller
                             $row[$key] = json_encode($row[$key]);
                     }
 
+                    if ($id_header)
+                        return array_merge(
+                            [$id_header => sprintf($id_format, $id)], $row);
+                    else
                         return $row;
+
                 });
 
             $all_rows = $all_rows->concat($rows);
+            $id += 1;
+        }
+
+        if ($id_header) {
+            $header->prepend($id_header);
         }
 
         return (object) [

config/experiment.php

@@ -6,6 +6,13 @@ return [
      */
     'n-a-text' => 'N/A',
 
+    /**
+     * header field of a running index added by the csv export.
+     */
+    'csv-id-header' => env('EXPERIMENT_CSV_ID_HEADER', null),
+    'csv-id-header-start' => env('EXPERIMENT_CSV_ID_HEADER_START', 1),
+    'csv-id-header-format' => env('EXPERIMENT_CSV_ID_HEADER_FORMAT', '%d'),
+
     /**
      * The token for the next and submit route.
      * If the token is null, everyone can access these routes.