How to get items are not in a collection in Laravel Eloquent? - php

Question

In my Laravel 6.x project I have Product model, Warehouse and WarehouseProduct models.
In the Product I store the base information of my products. In the WarehouseProduct I store the stock amount informations about products in warehouse. Of course I have many warehouses with many products.
My Product looks like this:
class Product extends Model
{
protected $fillable = [
'name',
'item_number',
// ...
];
}
The Warehouse looks like this:
class Warehouse extends Model
{
protected $fillable = [
'name',
'address',
// ...
];
public function products() {
return $this->hasMany(WarehouseProduct::class);
}
public function missingProduct() {
// here I need to return a Product collection which are not in this Warehouse or the
// stored amount is 0
}
}
Finally the WarehouseProduct looks like this:
class WarehouseProduct extends Model
{
protected $fillable = [
'product_id',
'warehouse_id',
'amount',
// ...
];
public function product() {
return $this->belongsTo(Product::class, 'product_id');
}
public function warehouse() {
return $this->belongsTo(Warehouse::class, 'warehouse_id');
}
How can I get a Product collection which are not stored in a Warehouse or the amount is 0?

Answer 1

Something like this should work:
use App\Product;
public function missingProduct() {
$excludedProducts = $this->products()->where('amount', '>', 0)->pluck('id');
return Product::whereNotIn('id', $excludedProducts)->get();
}
Based on #KarolSobański's solution, when you add a warehouse_products relation to your product model:
use App\Product;
use Illuminate\Database\Eloquent\Builder;
public function missingProduct() {
return Product::whereDoesntHave('warehouse_products', function (Builder $query) {
$query->where('warehouse_id', $this->id);
})->orWhereHas('warehouse_products', function (Builder $query) {
$query->where('warehouse_id', $this->id);
$query->where('amount', 0);
})->get();
}

Answer 2

The shortest answer might be similar to this:
Product::doesntHave('warehouse_products')
->orWhereHas('warehouse_products', function (Builder $query) {
$query->where('amount', '=', 0)
})->get();
Although I am not sure if the above works.
But the following longer query certainly resolves the issue:
Product::where(function ($query) {
$query->doesntHave('warehouse_products');
})->orWhere(function ($query) {
$query->whereHas('warehouse_products', function (Builder $query) {
$query->where('amount', '=', 0);
});
})->get();