laravel can't delete a row with one to many relation - laravel

Question

I have one to many relation in my project ( the user has many details ), and when i delete any user row it says
SQLSTATE[23000]: Integrity constraint violation: 1451 Cannot delete or update a parent row: a foreign key constraint fails (`sehhatys_saudi`.`details`, CONSTRAINT `details_user_id_foreign` FOREIGN KEY (`user_id`) REFERENCES `users` (`id`)) (SQL: delete from `users` where `id` = 9)
the details table migration
Schema::create('details', function (Blueprint $table) {
$table->id();
$table->bigInteger('user_id')->unsigned();
$table->string('check_date', 100);
$table->string('result_date', 100);
$table->string('result', 100);
$table->string('check_center', 100);
$table->timestamps();
$table->foreign('user_id')->references('id')->on('users')->onDelete('cascade');
});
the User model
<?php
namespace App\Models;
use Illuminate\Database\Eloquent\Factories\HasFactory;
use Illuminate\Database\Eloquent\Model;
class User extends Model
{
use HasFactory;
protected $fillable = ['name', 'name_en', 'national_id',
'birth_date', 'user_password', 'nationality', 'nationality_en',
'vaccine_type_one', 'vaccine_type_one_en', 'date_one',
'batch_number_one', 'vaccine_type_two', 'vaccine_type_two_en',
'date_two', 'batch_number_two', 'report_id', 'qr_url', 'access_token',
'phone', 'email', 'social', 'social_en', 'weight', 'height', 'mass',
'blood_pressure', 'blood_sugar', 'waist', 'hypertension',
'hypertension_en', 'diabetes', 'diabetes_en', 'city', 'city_en',
'health_center', 'health_center_en'];
public function details(){
return $this->hasMany('App\Detail');
}
}
the Detail model
<?php
namespace App\Models;
use Illuminate\Database\Eloquent\Factories\HasFactory;
use Illuminate\Database\Eloquent\Model;
class Detail extends Model
{
use HasFactory;
protected $fillable = ['user_id', 'check_date', 'result_date',
'result', 'check_center'];
public function user(){
return $this->belongsTo('App\User');
}
}
the delete function for the user row
public function delete($id)
{
User::findOrFail($id)->delete();
return redirect(route('users.all'));
}
even when edited the delete function and make it like this
public function delete($id)
{
$user = User::findOrFail($id);
$user->details()->delete();
$user->delete();
return redirect(route('users.all'));
}
it returns this error
Class "App\Detail" not found

Answer 1

The name space for your Detail Model is namespace App\Models; While you are using App\Detail in User.php.
The relation in User model should be:
public function details(){
return $this->hasMany('App\Models\Detail');
}
If you are using laravel-8 it should be like:
public function details(){
return $this->hasMany(App\Models\Detail::class);
}