HasMany Delete Parents: Validate or Cascade

In a hasMany relationship, what should happen with the children's record if you delete the parent record? I will show you three ways how to deal with that situation.

Here are our options:

1. Validation on the Laravel level: How can that error be processed more gracefully?
2. Validation on DB level: in Laravel migrations.
3. Using soft-deletes instead of deleting anything.

Laravel Project

First, the project setup and the problem itself.

In the project, we have two Models: Company and Contact. A contact belongs to a company.

database/migrations/xxx_create_companies_table.php:

Schema::create('companies', function (Blueprint $table) {
    $table->id();
    $table->string('company_name');
    $table->string('company_address');
    $table->string('company_website');
    $table->string('company_email');
    $table->timestamps();
});

database/migrations/xxx_create_contacts_table.php:

Schema::create('contacts', function (Blueprint $table) {
    $table->id();
    $table->foreignId('company_id')->constrained();
    $table->string('contact_name');
    $table->string('contact_last_name');
    $table->string('contact_phone_1');
    $table->string('contact_phone_2');
    $table->string('contact_email');
    $table->string('contact_skype');
    $table->string('contact_address');
    $table->timestamps();
});

To delete a company in the Controller, simply call the delete() method on the Company Model, which comes from the Route Model Binding.

use App\Models\Company;
use Illuminate\Http\RedirectResponse;
 
class ContactCompanyController extends Controller
{
    // ...
 
    public function destroy(Company $contactCompany): RedirectResponse
    {
        $contactCompany->delete();
 
        return redirect()->back();
    }
}

When the delete method is executed without any additional checks, the Integrity constraint violation error is shown.

Now, what are our options to solve it?

Option 1: Laravel Validation on Delete

Let's validate if the company has children of contacts. If it does, do not allow deleting them. There are a few ways to do that, but the most straightforward is adding an...