Laravel Factory Logic - php

Question

I have the factory below. When I set it to create more than one model, the ID does not seem to increment. Please help me understand how I can make this code work so the ID increments each time.
<?php
/* #var $factory \Illuminate\Database\Eloquent\Factory */
use App\PurchaseOrder;
use Faker\Generator as Faker;
use Illuminate\Support\Facades\DB;
$factory->define(PurchaseOrder::class, function (Faker $faker) {
DB::select(DB::raw('SET FOREIGN_KEY_CHECKS=0'));
$numberOfLines = rand(1, 5);
$id = PurchaseOrder::all()->last()->id + 1?? 1;
for ($i = 0; $i < $numberOfLines; $i++) {
$line = factory(App\Line::class)->make([
'purchase_order_id' => $id,
]);
$line->save();
};
$lines = App\Line::where('purchase_order_id', $id)->get();
DB::select(DB::raw('SET FOREIGN_KEY_CHECKS=1'));
return [
'total_price_ex_vat' => $lines->sum('price_ex_vat'),
'total_price_inc_vat' => $lines->sum('price_inc_vat'),
'revised_total_price_ex_vat' => $lines->sum('revised_price_ex_vat'),
'revised_total_price_inc_vat' => $lines->sum('revised_price_inc_vat'),
'deliver_to' => $faker->words(2, true),
'requested_staff_id' => factory(App\Staff::class)->create()->id ,
'auth_staff_id' => Null,
'supplier_id' => factory(App\Supplier::class)->create()->id,
'rejection_code_id' => Null,
'status_id' => 1,
'status_changed_date' => date('Y-m-d'),
'user_id' => factory(App\User::class)->create()->id,
];
});

Answer 1

You have table PurchaseOrder dependent on Lines, and Lines dependent on PurchaseOrder. I believe you should review your db design then, as this seems quite weird.
Why don't you avoid to use Lines in PurchaseOrder and load it as an attribute inside the PurchaseOrder model with an accessor?
For more info: https://laravel.com/docs/5.8/eloquent-mutators#defining-an-accessor