Laravel 5.4一对多关系（检查数据透视表中是否存在记录）

I want to check if current user already has this car.

User.php:

public function car()
    {
        return $this->hasMany(Car::class);
    }

Car.php

public function user()
    {
       return $this->belongsTo(User::class);
    }

For example, I'm passing to view all cars from cars table and I want to check if current user already has this car:

@foreach( $cars as $car )

   @if(Auth::user()->cars->where('car_id', $car->id)->exists())

        You have this car!

   @else

        Buy this car!

   @endif

@endforeach

Now, this code returns an error:

Call to a member function where() on null

How can I check if User already has this car?

2 Problems:

First the typo car/cars.

Second, you have public function car() so it should be Auth::user()->car()->where('car_id', $car->id)->exists() for condition chaining.

Check out the "One To Many" Section in Laravel 5.4 Documentation about chaining query conditions (pretty much at the end of the section).