php - Getting foreign key name through multiple relationships in Laravel blade view

one text

I am trying to get a foreign key name through a relationship of multiple foreign key names in my Laravel blade view, but it isn't bringing back the foreign key name and giving me a "Trying to get property 'location' of non-object

In my blade view I am trying to get the foreign key name like this:

<input type="text" class="form-control" value="{{ $document->office->location->location_name }}" disabled> 

This is my document model:

class Document extends Model
{

    protected $fillable = [
      'doc_code',
      'doc_name',
      'doc_description',
      'office_id',
    ];

    public function office() {
      return $this->belongsTo(Office::class);
    }
}
 

This is my office model:

class Office extends Model
{

    protected $fillable = [
      'location_id',
      'office_name',
    ];

    public function location() {
      return $this->belongsTo(Location::class);
    }
}
 

This is my location model:

class Location extends Model
{

    protected $fillable = [
      'location_name',
      'location_address',
    ];

}
 

This is the code for my view in my Document Controller:

public function show($id)
    {
        $office = Office::all();
        $document = Document::find($id);

        return view('documents.show',compact('document', 'office'));
    } 

What am I missing in order to retrieve the foreign key name based on another foreign key like the above?