Search query through foreign key - laravel

Question

I'm trying to search through my comments on the username connected to the user_id Foreign Key
Tables:
Comment- id, comment, user_id, timestamps
User - id, name, username
Models:
class Comment extends Model
{
public function author()
{
return $this->belongsTo('App\User','user_id');
}
}
Controller:
public function index(Request $request)
{
$comments = Comment::query()->orderby('created_at', 'DESC');
$id=$request->]
return view('comments.index')->withComment($comment);
}
View:
<div class="panel-body">
{!! Form::open(['route' => 'comments.index', 'method' => 'GET']) !!}
<div class="col-md-5">
{!! Form::label('id', 'Search By ID:') !!}
{!! Form::text('id', null, array('class' => 'form-control')) !!}
</div>
<div class="col-md-5">
{!! Form::label('username', 'Search By Username:') !!}
{!! Form::text('username', null, array('class' => 'form-control')) !!}
</div>
<div class="col-md-2">
{!! Form::submit('Find Comments', array('class' => 'btn btn-send ')) !!}
</div>
{!!Form::close()!!}
</div>
#foreach($comment as $comments)
//data
#endforeach

Answer 1

I believe it is failing at the builder level because you are trying to query on an object that is not yet known. IE the author LIKE must be part of a sub query:
$comments = Comment::whereHas('author', function ($query) use($request) {
$query->where(users.username, 'LIKE', $request->input('username') )
}])->orderby('created_at', 'DESC')->get();
I see you will have to write the query a second time, but I think this may be successful for you.