how to use a model function in scope in laravel? - laravel

Question

I have two tables
1- Products
2- Discounts
I want to select all discounted products, but there is a problem, in Discount table there is no product_id, there is array of product id like : ["1","4","23"] which means this discount is used for products with id of 1 or 4 or 23.
I already created a function in my product model that defines if the product has discount or not and use it like :
$product->hasDiscount(); //returns 1 or 0
what I need actually?
I need an scope for my product model like below to use in my select query to get all discounted products:
public function scopeDiscounted($query)
{
return $query->where($this->hasDiscount() , '=' , 1);
// I know this code is wrong, I just want to explain the needed code result
}

Answer 1

Lets start by normalizing your data, create the following table and loop in a migration.
public function up()
{
Schema::create('discount_product', function (Blueprint $table) {
$table->unsignedInteger('discount_id');
$table->unsignedInteger('product_id');
// add foreign keys if you like
});
Discount::all()->each(function (Discount $discount) {
$productIds = json_encode($discount->productIds);
foreach ($productIds as $productId) {
$discount->saveMany(Product::whereIn('id', $productIds)->get());
}
});
}
To make this migration work, you have to create the relationships before running the migration. I was lazy using models in the migration, the best approach is to use the DB facade.
class Discount {
public function products()
{
return $this->belongsToMany(Product::class);
}
}
class Product {
public function discounts()
{
return $this->belongsToMany(Discount::class);
}
}
Now you should be able to get all discounted products and you could put this in your scope.
$discountedProducts = Product::whereHas('discounts', function ($query) {
$query->where('active', true);
$query->whereDate('expire_at', '>=', now())
})->get();