get函数返回空数组laravel

I need some help getting my user_id from my pdf_files table, but for some reason it keep giving me an empty array when I try using $request = all() --> return me {} and dd($downloads) return me this Collection {#233 ▼ #items: [] }. Do I have to use with statement or anything? I saw some people using it but do I really need it? Thanks for helping

Code:

Controller:

public function downfunc(Request $request){
//  $downloads = new pdfFile;
$downloads=pdfFile::where('user_id', $request->user_id)->get();
//$downloads=DB::table('pdf_files')->get(); --> this code return results
//dd($downloads);
//return $request->all();
return view('download.viewfile',compact('downloads'));

}

download.blade.php

<table class="table table-bordered">
                    <thead>
                        <th>Name of File</th>
                        <th>Action</th>
                    </thead>

                    <tbody>

                    @foreach($downloads as $down)
                        <tr>
                            <td>{{$down->file_name}}</td>
                            <td>
                            <a href="download/{{$down->file_name}}" download="{{$down->file_name}}">
                                <button type="button" class="btn btn-primary">
                                <i class="glyphicon glyphicon-download">
                                    Download
                                </i>
                                </button>
                            </a>
                            </td>
                        </tr>
                    @endforeach
                    </tbody>
                </table>

pdfFile model:

protected $fillable = array('file_name','file_size','user_id');

public function personal_infos() {
    return $this->belongsTo('App\personal_info', 'user_id', 'id');
}

Please make sure your $request->user_id is valid

You can check by run sql manually.