Laravel how to add a custom function in an Eloquent model?

I have a Product model

class Product extends Model
{
    ...

    public function prices()
    {
        return $this->hasMany('AppPrice');
    }

    ...
}

I want to add a function which will return the lowest price, and in controller I can get the value using:

Product::find(1)->lowest;

I added this in Product model:

public function lowest()
{
    return $this->prices->min('price');
}

but I got an error saying:

Relationship method must return an object of type IlluminateDatabaseEloquentRelationsRelation

And if I use Product::find(1)->lowest();, it will work. Is it possible to get Product::find(1)->lowest; to work?

Any help would be appreciated.

Answer

When you try to access a function in the model as a variable, laravel assumes you’re trying to retrieve a related model. They call them dynamic properties. What you need instead is a custom attribute.

Laravel 6 docs: https://laravel.com/docs/6.x/eloquent-mutators

add following method to your model:

public function getLowestAttribute()
{
    //do whatever you want to do
    return 'lowest price';
}

Now you should be able to access it like this:

Product::find(1)->lowest;