Can't pass variable to a Dompdf loadView method

Probably because you named the variable $data instead of $card, whereas it was named $card where you said it was working (without rendering the pdf)

$pdf = PDF::loadView('print.print',array('card' =>$card));  // name the variable card

You'll also need to retrieve $card from the db like you do in your first code snippet, in order to pass it to the view.

public function print_pdf()
{
    $card = Card::all(); // you're not passing an $id to print_pdf() like you are the show() method
    $pdf = PDF::loadView('print.print', ['card' => $card]);
    return $pdf->download('card.pdf');
}

@Cronix, thank you for your answer! I try to do

use App\Card; 
use PDF;
............
public function show($id)
    {
      $card = Card->where('id',$id)->get(); //or another model query
       $this->print_pdf($card); 
    }
//and call print_pdf method with $card parameter
public function print_pdf($card)
{
   $pdf = PDF::loadView('print.print', ['card' => $card]);
    return $pdf->download('card.pdf');
}

dd($pdf) returns some array but if i use

   $pdf = PDF::loadView('print.print', ['card' => $card]);
    return $pdf->download('card.pdf');

error occurs: Maximum execution time of 30 seconds exceeded in vendor\dompdf\dompdf\src\Css\Stylesheet.php file (i want to display in pdf not so much data, only a few rows)

Try changing

$card = Card->where('id',$id)->get(); //or another model query

to

$card = Card::where('id',$id)->get(); //or another model query

And also try using

 $pdf = PDF::loadView('print.print', compact('card'));

this worked for me $pdf = PDF: :loadView('print. print', compact('card'));