title: dynamic fields in the rails view
body: <p>I want to show fields from the database dynamically.i.e, if suppose
  in one case my @user object reads from users table
           @user = User.new </p>
  
  <p>in another case @user object reads from posts table
           @user = Post.new</p>
  
  <p>Then dynamically my view(new page) shows the fields based on the model selected.</p>