Laravel Has One Relation changing the identifier value - laravel

Question

I'm not sure this is a real relation. I will try to explain the best way I can.
So first of all, I have three models :
Appartement,
AppartementPrice
The AppartementPrice depends on :
- appartement_id
I would like the AppartementPrice to be retrieve like that :
If there is a specific price for the appartement, then retrieve it, If not retrieve the price for all appartement which is stored in the database with an appartement_id = 0.
So basically what I would like is to do something like that :
public function price()
{
if(isset($this->hasOne('AppartementPrice')->price) // Check that relation exists
return $this->hasOne('AppartementPrice');
else
return $this->hasOne('AppartementPrice')->where('appartement_id', '0');
}
But this is not working.
It does not retrive me the default price.
I guess anyway this is not a best practice ?
I first tried to get the informations like that :
//Check if appartment has a specific price or retrieve default
if($priceAppartement = AppartementPrice::getPriceByCompanyAppartement($this->id))
return $priceAppartement;
else
return AppartementPrice::getDefaultPrice();
But I had this error :
Relationship method must return an object of type Illuminate\Database\Eloquent\Relations\Relation
when doing :
echo $app->price->price;
How can I check that a relation exists ? And is there a way to do as I describe ?
Thank you

Answer 1

You can't replace relation like this, as what you intend is not logical - you want to retrieve relation that doesn't exist.
Instead you can do this:
public function getPriceAttribute()
{
return ($this->priceRelation) ?: $this->priceDefault();
}
public function priceDefault()
{
// edit: let's cache this one so you don't call the query everytime
// you want the price
return AppartmentPrice::remember(5)->find(0);
}
public function priceRelation()
{
return $this->hasOne('AppartementPrice');
}
Then you achieve what you wanted:
$app->price; // returns AppartmentPrice object related or default one
HOWEVER mind that you won't be able to work on the relation like normally:
$price = new AppartmentPrice([...]);
$app->price()->save($price); // will not work, instead use:
$app->priceRelation()->save($price);

Answer 2

First of all something really important in Laravel 4.
When you do not use parentheses when querying relationship it means you want to retreive a Collention of your Model.
You have to use parentheses if you want to continue your query.
Ex:
// for getting prices collection (if not hasOne). (look like AppartementPrice)
$appartment->price;
// for getting the query which will ask the DB to get all
//price attached to this appartment, and then you can continue querying
$priceQuery = $appartment->price();
// Or you can chain your query
$appartment->price()->where('price', '>', 0)->get() // or first() or count();
Secondly, your question.
//Appartement Model
// This function is needed to keep querying the DB
public function price()
{
return $this->hasOne('AppartementPrice')
}
// This one is for getting the appartment price, like you want to
public function getAppartmentPrice()
{
$price_object = $this->price;
if (!$price_object) // Appartment does not have any price {
return AppartementPrice->where('appartement_id', '=', 0)->get();
}
return $price_object;
}