Laravel - Store data with a Polymorphic relation - php

Question

I'm new to Laravel and would I'm confused on how to properly store a data from a form with a polymorphic relation. I have three models.
Salary Grade Model
public function salaryallowance() {
return $this->morphOne('App\SalaryAllowanceModel', 'salary');
}
Salary Matrix Model
public function salaryallowance() {
return $this->morphOne('App\SalaryAllowanceModel', 'salary');
}
Salary Allowance Model
public function salary() {
return $this->morphTo();
}
Salary Allowance Controller
public function create()
{
$getSalaryAllowanceWithSalary = SalaryAllowanceModel::all();
$getPosition = PositionModel::pluck('position_name', 'id');
$getSalaryGrade = SalaryGradeModel::pluck('salary_grade', 'id');
return view('SalaryAllowanceView.add', compact('getSalaryAllowanceWithSalary', 'getPosition', 'getSalaryGrade'));
}
public function store(Request $request) {
SalaryAllowanceModel::create ([
'salary_id' => $request->position,
'salary_type' => get_class($request),
'salary_allowance' => $request->allowance,
'salary_transportation' => $request->transportation,
'salary_medical' => $request->medical,
'salary_education' => $request->education,
'salary_housing' => $request->housing,
'salary_clothing' => $request->clothing
]);
return back();
}
Blade.php
<div class="form-group col-md-12 row">
<label class="col-md-4 col-form-label text-md-right">{{ __('Position') }}</label>
<div class="col-md-6">
<select name="position" class="form-control">
<option value="0">Please Select Position</option>
#foreach ($getPosition as $id => $position)
<option value="{{$id}}">{{ $position }}</option>
#endforeach
</select>
</div>
</div>
<div class="form-group col-md-12 row">
<label class="col-md-4 col-form-label text-md-right">{{ __('Allowance') }}</label>
<div class="col-md-6">
<input type="text" class="form-control" name="allowance">
</div>
</div>
I'm having a hard time to do a syntax for storing the data. I want the ID to be based on the selected drop-down.
EDIT:
I have tried using this approach but I'm getting the wrong ID to be saved in the column salary_id of Salary Allowance table. The model is properly saved in the salary_type.
public function store(Request $request)
{
$post = SectionModel::find(2);
$comment = new SalaryAllowanceModel;
$comment->salary_allowance = $request->allowance;
$comment->salary_id = $request->position;
$post->salaryallowance()->save($comment);
return back();
}
EDIT 2: SOLVED Finally I have found the solution. Posting answer for people who have the same problem
public function store(Request $request)
{
$post = SalaryMatrixModel::find($request->position);
$comment = new SalaryAllowanceModel;
$comment->salary_allowance = $request->allowance;
$comment->salary_id = $request->position;
$post->salaryallowance()->save($comment);
}