Laravel - Seeding Relationships

Laravel: Seeding table with several belongs to relationship using factories

You have to use associate():

public function seed()
{
    factory(User::class, 10)->create();
    factory(Category::class, 10)->create();
    factory(Post::class, 100)->make()->each(function ($post) {
        $post->user()->associate(User::inRandomOrder()->first());
        $post->category()->associate(Category::inRandomOrder()->first());
        $post->save();
    });
}

Also User::all()->random(1) will return a collection and not a model, which will throw an exception, I replaced it with Model::inRandomOrder()->first(), which will fetch a random model from the database.

From the docs:

When updating a belongsTo relationship, you may use the associate
method. This method will set the foreign key on the child model:

$account = App\Account::find(10);

$user->account()->associate($account);

$user->save();

Update

In your Modelfactory:

/** @var Factory $factory */
$factory->define(Post::class, function (Faker\Generator $faker) {
    return [
        // not sure why you do this, is it not a autoincrement column?
        'id' => $faker->unique()->randomNumber(3), 
        'name' => $faker->realText($maxNbChars = 200, $indexSize = 2),
        'category_id' => function () {
            if ($category = Category::inRandomOrder()->first()) {
                return $category->id;
            }

            return factory(Category::class)->create()->id;
        },
        'user_id' => function () {
            if ($user = User::inRandomOrder()->first()) {
                return $user->id;
            }

            return factory(User::class)->create()->id;
        },
    ];
});

In your seeder:

public function seed()
{
    factory(User::class, 10)->create();
    factory(Category::class, 10)->create();
    factory(Post::class, 100)->create();
}

Laravel 8: How to seed a pivot table in many to many relationship

so first you can check if in the database there is Atg, if no you can seed like you do, otherwise you can seed Debtor then save Atg in relations(->atg() is your relation name so improve it if i wrote wrong name) like so:

P.S. Also i removed ->count(1) from Debtor because by default it creates one item.

<?php

namespace Database\Seeders;

use App\Models\Atg;
use App\Models\Debtor;
use Illuminate\Database\Seeder;

class DebtorSeeder extends Seeder
{
    /**
     * Run the database seeds.
     *
     * @return void
     */
    public function run()
    {
        $atg = Atg::first();
        if($atg){
           $debitor = Debtor::factory()
                ->create();

           $debitor->atg()->save($atg);
        }else {
           $debitor = Debtor::factory()
                ->hasAtg(1)
                ->create();
        }
    }
}

Seed data with relationship in Laravel

You can query which roles you want to assign to the companies and related them to the created records like this:

class CompanySeed extends Seeder
{
    public function run()
    {
        $contractorRole = Role::whereName('Contractor')->firstOrFail();
        $ownerRole = Role::whereName('Owner')->firstOrFail();

        factory(Company::class, 10)->create()->each(function ($company) use ($contractorRole, $ownerRole) {
            $company->roles()->attach([
                $contractorRole->id,
                $ownerRole->id
            ]);
        });
    }
}

You can check the doc for relating records https://laravel.com/docs/5.6/eloquent-relationships#inserting-and-updating-related-models

How to seed related data during migration in Laravel?

This is what worked for me:

App\Models\Client::factory(10)->create()->each(function ($client) {
    $client->contract()->save(Contract::factory()->make());
});

Seeding Relationship one to many in Laravel

attach for many to many relationships, you don't need device_user table for one to many relationship, in one to many you should create a column with name user_id in device table and just it. after that you can insert data in device table with user_id. and get user relationship with

Device::user()->get();

Laravel Seed with Relationship (Real Data)

Your Car model:

public function brand()
{
    return $this->belongsTo(\App\Brand::class, 'brand_id');
}

Your Brand model:

public function cars()
{
    return $this->hasMany(\App\Car::class);
}

Your cars migration:

public function up()
{
    Schema::create('cars', function (Blueprint $table) {
        $table->increments('id');
        $table->string('name');
        $table->enum('type_of_car', ['small', 'medium', 'large']); // just extra example
        $table->year('year');
        $table->mediumInteger('horse_power');

        // car's brand id below
        $table->unsignedInteger('brand_id');
        $table->foreign('brand_id')->references('id')->on('brands')->onDelete('cascade');
    });
}

To seed your cars table, you can insert any id from brands table into brand_id in your cars table, for example:

Car::create([
    'name'        => 'S4',
    'type_of_car' => 'medium',
    'year'        => '2014',
    'horse_power' => 333,
    'brand_id'    => 3 // <-- this id should exist in brands table
]);

If you are seeding cars with random brands, you can insert a random brand id instead of hardcoding the id (like I did above with brand_id being 3):

...
    'brand_id' => \App\Brand::all('id')->random()->id
]);