Laravel saving polymorphic model doesn't have a default value - php

Question

I'm working on a Laravel 9 project. I'm new to Polymorphic relationships and believe I need to define one.
In my application, I have a parent model called Application that has a single ApplicationGBPayday model, but it could have other models in the future for different products/countries.
I've defined my Application model schema to contain a modelable morph fieldset, and in my controller where I create an Application I then need to create and link the ApplicationGBPayday, but I'm getting an error right now:
Illuminate\Database\QueryException: SQLSTATE[HY000]: General error: 1364 Field 'modelable_type' doesn't have a default value
My controller I'm doing:
// create application
$application = Application::create([
'user_id' => $affiliate->user_id,
'company_id' => $affiliate->company_id,
'country_id' => $affiliate->affiliate_product->country->id,
'product_id' => $affiliate->affiliate_product->product->id,
'serve_method_id' => $affiliate->affiliate_product->serve_method->id,
'application_form_id' => $affiliate->affiliate_product->application_form->id,
'pingtree_group_id' => $affiliate->affiliate_product->pingtree_group->id,
'affiliate_id' => $affiliate->id,
'thread_uuid' => $threadUUID,
'status' => 'pending',
'submitted_at' => $submittedAt
]);
$payday = ApplicationGBPayday::create($request->all());
And here's my model for Application:
<?php
namespace App\Models;
use Illuminate\Database\Eloquent\Factories\HasFactory;
use Illuminate\Database\Eloquent\Model;
use Illuminate\Database\Eloquent\SoftDeletes;
use App\Casts\Json;
class Application extends Model
{
use HasFactory, SoftDeletes;
/**
* The table associated with the model.
*
* #var string
*/
protected $table = 'applications';
/**
* The attributes that aren't mass assignable.
*
* #var array
*/
protected $guarded = [];
/**
* The attributes that should be cast.
*
* #var array<string, string>
*/
protected $casts = [
'submitted_at' => 'datetime',
];
/**
* Get the parent modelable model.
*/
public function modelable()
{
return $this->morphTo();
}
}
And ApplicationGBPayday:
<?php
namespace App\Models;
use Illuminate\Database\Eloquent\Factories\HasFactory;
use Illuminate\Database\Eloquent\Model;
use App\Casts\Json;
class ApplicationGBPayday extends Model
{
use HasFactory;
/**
* The table associated with the model.
*
* #var string
*/
protected $table = 'application_gb_paydays';
/**
* The attributes that aren't mass assignable.
*
* #var array
*/
protected $guarded = [];
/**
* The attributes that should be cast.
*
* #var array<string, string>
*/
protected $casts = [
'buyer_list' => Json::class,
'buyer_list_pending' => Json::class,
'buyer_list_accepted' => Json::class,
'buyer_list_declined' => Json::class,
'buyer_list_invalid' => Json::class,
'buyer_list_skipped' => Json::class,
'other_data_json' => Json::class,
'response_json' => Json::class,
];
/**
* Get the model's application
*/
public function application()
{
return $this->morphOne(Application::class, 'modelable');
}
}
I'm struggling to figure out how to save the morph fields since they can't be null here, yet I need the application created first and then the payday? What am I missing?
UPDATE
I've tried:
// create application
$application = Application::create([
'user_id' => $affiliate->user_id,
'company_id' => $affiliate->company_id,
'country_id' => $affiliate->affiliate_product->country->id,
'product_id' => $affiliate->affiliate_product->product->id,
'serve_method_id' => $affiliate->affiliate_product->serve_method->id,
'application_form_id' => $affiliate->affiliate_product->application_form->id,
'pingtree_group_id' => $affiliate->affiliate_product->pingtree_group->id,
'affiliate_id' => $affiliate->id,
'thread_uuid' => $threadUUID,
'status' => 'pending',
'submitted_at' => $submittedAt
]);
$payday = new ApplicationGBPayday($request->all());
$application->modelable()->save($payday);
Which gives me:
Illuminate\Database\QueryException: SQLSTATE[HY000]: General error: 1364 Field 'modelable_type' doesn't have a default value (SQL: insert into applications