hasMany and belongsTo Laravel - mysql

Question

I have 3 models. User, Notification and Lmo Notifications. The relation is a User hasMany Notifications and Notification has many LmoNotification.
to insert the notification and lmoNotification i created two models and controllers and they have separate database tables.
My problem is when i enter notifications into the database, it inserts data without any problem with user_id as the foreign key. But next when i try to enter the lmonotification, it gives an error.
Notification Model:
class Notification extends Model
{
protected $table = "notifications";
protected $fillable = [
'unit_code', 'unit_name', 'project_title', 'project_ref_number', 'storage_location', 'keeper_name', 'user_id',
];
public function user(){
return $this->belongsTo('App\User');
}
}
LmoNotification Model
class AddLmoNotification extends Model
{
/**
* The attributes that are mass assignable.
*
* #var array
*/
protected $table = "lmo_notifications";
protected $fillable = [
'lmo_name', 'lmo_risk_level', 'lmo_quantity', 'lmo_volume', 'notification_id',
];
public function notification(){
return $this->belongsTo('App\Notification');
}
}
Notification controller to create the notification
public function create(Request $request)
{
$notification = Notification::create([
'unit_code'=>$request->unit_code,
'unit_name'=>$request->unit_name,
'project_title'=>$request->project_title,
'project_ref_number'=>$request->project_ref_number,
'storage_location'=>$request->storage_location,
'keeper_name'=>$request->keeper_name,
'user_id'=>Auth::user()->id
]);
return redirect()-> route('show.lmo_form', $notification->id);
// return view('ApplicationForms.notifi', $notification);
}
Lmonotification controller
$notification = new Notification;
/*this loop is because im adding rows dynamically to the table*/
$count = count($request->input('lmo_name'));
for ($i=0; $i<$count; $i++){
$data = AddLmoNotification::create([
'lmo_name'=>$request->lmo_name[$i],
'lmo_risk_level'=>$request->lmo_risk_level[$i],
'lmo_quantity'=>$request->lmo_quantity[$i],
'lmo_volume'=>$request->lmo_volume[$i],
'notification_id'=>$notification->id
]);
return response($data);
}
//return response($notification);
return redirect()->route('show.go_to_notification');
}
web.php
Route::prefix('notification')->group(function(){
/*show notification main page*/
Route::get('/', 'HomeController#getNotificationPage')->name('show.go_to_notification');
/*route to lmo_notification_form*/
Route::get('/personal_information_notification_form', 'HomeController#getNotificationForm');
/*route to biohazardous material notification form*/
Route::get('/biohazardous_material_notification_form', 'HomeController#getotherNotificationForm')->name('show.biohazardous_material_notification_form');
/*submit lmo notification route*/
Route::post('/personal_information_notification_form/submit', 'NotificationController#create')->name('submit.personal_Info_Notification');
/*Rtoute to lmo form*/
Route::get('/personal_information_notification_form/add_lmo/{notification_id}', 'HomeController#getlmoNotificationForm')->name('show.lmo_form');
/*Route to submit lmo list for notification*/
Route::post('/personal_information_notification_form/add_lmo', 'LmoNotificationController#create')->name('submit.lmo_list');
});
Notification table
Schema::create('notifications', function (Blueprint $table) {
$table->increments('id');
$table->integer('user_id')->unsigned();
$table->foreign('user_id')->references('id')->on('users')->onDelete('cascade')->onUpdate('cascade');
$table->string('unit_code')->nullable();
$table->string('unit_name')->nullable();
$table->string('project_title')->nullable();
$table->string('project_ref_number')->nullable();
$table->string('storage_location');
$table->string('keeper_name');
$table->timestamps();
});
Lmo Notification table
public function up()
{
Schema::create('lmo_notifications', function (Blueprint $table) {
$table->increments('id');
$table->integer('notification_id')->unsigned();
$table->foreign('notification_id')->references('id')->on('notifications')->onDelete('cascade')->onUpdate('cascade');
$table->string('lmo_name');
$table->string('lmo_risk_level');
$table->string('lmo_quantity');
$table->string('lmo_volume');
$table->timestamps();
});
}
the notification table contains some personal details fields and the lmonotification contains list of products.
the error message says that
SQLSTATE[23000]: Integrity constraint violation: 1048 Column 'notification_id' cannot be null (SQL: insert into lmo_notifications (lmo_name, lmo_risk_level, lmo_quantity, lmo_volume, notification_id, updated_at, created_at) values (asd, medium, 2, 2, , 2017-05-09 22:35:15, 2017-05-09 22:35:15))
Please help.

Answer 1

There is nothing wrong with your relations setup. The problem starts where you set the notification_id of your new AddLmoNotification off of a model you instantiated with:
$notification = new Notification;
Note that as long as $notification is not persisted to database with:
$notification->save()
that notification will not have an ID assigned to it by the database, and thus, accessing its id attribute returns null. So you'll have to save the $notification model first, before creating any models that rely on its id attribute for their foreign-key fields.