How to use an instance of a class in its own class - php

Question

In Laravel 4.x I have a Customer Eloqeunt Model that has a relationship to a Customer_tel Eloquent Model:
class Customer extends Eloquent
{
public function tel()
{
return $this->hasMany('Customer_tel');
}
}
The Customer_tel table has a boolean column 'main'.
When I make an instance of the Customer Class in a view, then I can filter out the main number with the filter() method:
$Customer = Customer::find(1);
$Customer->tel->filter(function($tel)
{
if ($tel->main == true)
{
return true;
}
})->shift()->tel
But when I try to make a function in the class with the filter() method:
public function mainTel()
{
return $this->tel()->filter(function($tel)
{
if ($tel->main == true)
{
return true;
}
})->shift()->tel;
}
When I try to reference it in the view $Customer->mainTel, then it gives me an error "Call to undefined method Illuminate\Database\Query\Builder::filter()".
Why can't I filter the instance only outside of the class but not in the class? And is there a right way to do it?

Answer 1

Calling the method (tel()) returns the HasMany instance, upon which you can then call the query builder methods. Using Eloquent's magic properties, you can short-circuit it. So $customer->tel is equivalent to $customer->tel()->get(), which returns a collection. That is why it's working for you in your first example.
See the docs for more info.
A better option would be to do it in the query itself:
return $this->tel()->where('main', true)->pluck('tel');
Also note that you can create your own magic properties in Eloquent:
class Customer extends Eloquent {
public function tel()
{
return $this->hasMany('Customer_tel');
}
public function getMainTelAttribute()
{
return $this->tel()->where('main', true)->pluck('tel');
}
}
Now when you have a $customer model, you can call your magic method directly:
$tel = $customer::find(1)->main_tel;