How to upload file PDF using laravel?

I have an application based on Laravel 5 with file upload functionality. 1. I try to insert images(jpeg,bmp,png) and files(Docx,xlsx) so Everything works fine except uploading of PDF files. 2. Need help on how to insert files (pdf) using laravel? I use laravel framework with Mysql

    public function rules()
    {
    return [
    'proposition' => 'required',];
    $filename = count($this->input('filename'));
    foreach(range(0, $filename) as $index) {
        $rules['filename.' . $index] = 
    'required|mimes:pdf,jpeg,bmp,png,doc,docx,csv,xlsx|max:20000';
    }
    return $rules;
    }



   public function store(PropositionRequest $request)
   {
    $proposition = new Proposition();
    $prop = Proposition::create($request->all());
    $prop->saveTags($request->get('tags'));
     foreach ($request->filename as $filename) {
     $filename = $filename->store('filename');
     PropositionFiles::create([
     'proposition_id' => $prop->num_proposition,
      'filename' => $filename
        ]);
       }