BookStack\Repos\PageRepo::saveUpdateDraft PHP Method

    public function saveUpdateDraft(Page $page, $data = [])
    {
        $userId = user()->id;
        $drafts = $this->userUpdateDraftsQuery($page, $userId)->get();
        if ($drafts->count() > 0) {
            $draft = $drafts->first();
        } else {
            $draft = $this->pageRevision->newInstance();
            $draft->page_id = $page->id;
            $draft->slug = $page->slug;
            $draft->book_slug = $page->book->slug;
            $draft->created_by = $userId;
            $draft->type = 'update_draft';
        }
        $draft->fill($data);
        if (setting('app-editor') !== 'markdown') {
            $draft->markdown = '';
        }
        $draft->save();
        return $draft;
    }