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

Question

I have a Product model
class Product extends Model
{
...
public function prices()
{
return $this->hasMany('App\Price');
}
...
}
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 Illuminate\Database\Eloquent\Relations\Relation
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 1

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.
Before Laravel 9
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;
EDIT: New in Laravel 9
Laravel 9 offers a new way of dealing with attributes:
Docs: https://laravel.com/docs/9.x/eloquent-mutators#accessors-and-mutators
// use Illuminate\Database\Eloquent\Casts\Attribute;
public function lowest(): Attribute
{
return new Attribute(
get: function( $originalValue ){
//do whatever you want to do
//return $modifiedValue;
});
/**
* Or alternatively:-
*
* return Attribute::get( function( $originalValue ){
* // do whatever you want to do
* // return $modifiedValue;
* });
*/
}

Answer 2

Use Eloquent accessors
public function getLowestAttribute()
{
return $this->prices->min('price');
}
Then
$product->lowest;

Answer 3

you can use above methods or use following method to add a function direct into existing model:
class Company extends Model
{
protected $table = 'companies';
// get detail by id
static function detail($id)
{
return self::find($id)->toArray();
}
// get list by condition
static function list($name = '')
{
if ( !empty($name) ) return self::where('name', 'LIKE', $name)->get()->toArray();
else return self::all()->toArray();
}
}
Or use Illuminate\Support\Facades\DB; inside your function. Hope this help others.

Answer 4

why you just dont do this? i know , it's not what you asked for specificallyand it migh be a bad practice sometimes. but in your case i guess it's good.
$product = Product::with(['prices' => function ($query) {
$query->min('price');
}])->find($id);

Answer 5

change follow code
public function lowest()
{
return $this->prices->min('price');
}
to
// add get as prefix and add posfix Attribute and make camel case function
public function getLowestAttribute()
{
return $this->prices->min('price');
}