laravel eloquent has method code example

Example 1: associate laravel

When updating a belongsTo relationship, you may use the associate method. This 
method will set the foreign key on the child model:

	$account = App\Account::find(10);
	$user->account()->associate($account);
	$user->save();

When removing a belongsTo relationship, you may use the dissociate method. This
method will set the relationship foreign key to null:

	$user->account()->dissociate();
	$user->save();

Example 2: by default null eloquent user data in relationship in laravel 8

# simple handle in blade file 
{{ $post->author->name or 'No author' }}

# Model action 
public function author()
{
    return $this->belongsTo('App\Author')->withDefault();
}

public function author()
{
    return $this->belongsTo('App\Author')->withDefault([
        'name' => 'Guest Author',
    ]);
}