Laravel save related data in database - laravel

Question

I want to save question_id in answer table using post form
I tried to use foreach or functions but i always got null data
Controller
public function store(Request $request, Survey $survey)
{
$request->validate([
'answer' => 'required',
]);
$survey->option_name = unserialize($survey->option_name);
$answers = new Answer([
'answer' => $request->get('answer'),
'commentaire' => $request->get('commentaire'),
'user_id' => auth()->id(),
'last_ip' => request()->ip(),
'question_id' => $survey->questions,
'survey_id' => $survey->id,
]);
$answers->save();
return redirect()->action('SurveyController#view_survey_answers', [$survey->id]);
}
answers table
question table's row :
id
survey_id
title
timestamp
I got always null data or i tried using where but i got errors like id index doesn't exists...

Answer 1

View :
{!! Form::open(array('action'=>array('AnswerController#store', $survey->id))) !!}
#forelse ($survey->questions as $key=>$question)
<p class="flow-text">Question {{ $key+1 }} - {{ $question->title }}</p>
#if($question->question_type === 'text')
<div class="form-group">
<div class="input-field col s12">
<input id="answer" type="text" name="answer">
<label for="answer">Answer</label>
</div>
</div>
#elseif($question->question_type === 'textarea')
<div class="form-group">
<div class="input-field col s12">
<textarea id="textarea1" class="materialize-textarea" name="{{ $question->id }}[answer]"></textarea>
<label for="textarea1">Textarea</label>
</div>
</div>
#elseif($question->question_type === 'radio')
#foreach($question->option_name as $key=>$value)
<p style="margin:0px; padding:0px;">
#if($value === 'else')
<div class="form-group" style="margin-left: 20px;">
<input name="answer" class="custom-control-input" type="radio" id="{{ $value }}" value="{{$value}}"/>
<label class="custom-control-label" for="{{ $value }}">{{ $value }}</label>
<div id="textboxes" style="display: none">
<br>
<textarea class="form-control" name="commentaire" id="exampleFormControlTextarea1" rows="3" placeholder="Write a large text here ..."></textarea>
</div>
</div>
#else
<p style="margin:0px; padding:0px;">
<div class="form-group" style="margin-left: 20px;">
<input name="answer" class="custom-control-input" type="radio" id="{{ $value }}" value="{{ $value}}"/>
<label class="custom-control-label" for="{{ $value }}">{{ $value }}</label>
</div>
</p>
#endif
#endforeach
#elseif($question->question_type === 'checkbox')
#foreach($question->option_name as $key=>$value)
<p style="margin:0px; padding:0px;">
<div class="form-group">
<input type="checkbox" id="{{ $value }}" name="answer" value="{{$value}}"/>
<label for="{{$value}}">{{ $value }}</label>
</div>
</p>
#endforeach
#endif
<div class="divider" style="margin:10px 10px;"></div>
#empty
<span class='flow-text center-align'>Nothing to show</span>
#endempty
<div class="form-group">
{{ Form::submit('Submit Survey', array('class'=>'btn btn-success mt-4')) }}
</div>
{!! Form::close() !!}