MDL-68500 dataformat: allow instances to export to local file.

lib/classes/dataformat/spout_base.php

@@ -66,6 +66,23 @@ abstract class spout_base extends \core\dataformat\base {
         $this->renamecurrentsheet = true;
     }
 
+    /**
+     * Set the dataformat to be output to current file
+     */
+    public function start_output_to_file(): void {
+        $this->writer = \Box\Spout\Writer\Common\Creator\WriterEntityFactory::createWriter($this->spouttype);
+        if (method_exists($this->writer, 'setTempFolder')) {
+            $this->writer->setTempFolder(make_request_directory());
+        }
+
+        $this->writer->openToFile($this->filepath);
+
+        // By default one sheet is always created, but we want to rename it when we call start_sheet().
+        $this->renamecurrentsheet = true;
+
+        $this->start_output();
+    }
+
     /**
      * Set the title of the worksheet inside a spreadsheet
      *
@@ -114,4 +131,15 @@ abstract class spout_base extends \core\dataformat\base {
         $this->writer->close();
         $this->writer = null;
     }
+
+    /**
+     * Write data to disk
+     *
+     * @return bool
+     */
+    public function close_output_to_file(): bool {
+        $this->close_output();
+
+        return true;
+    }
 }