Now am a logged in user and I need to comment on a post. So the user and post are already created and now we need to create comment with post and user id on it.
@vinoth06 Good point on the associate(). That could very well allow you to have neither user_id nor post_id fillable. Sorry for the confusion, it's been a while since I tackled the 'owned by two' that wasn't a polymorphic thing.