title: How to unwrap nested Struct column into multiple columns?
body: <p>I'm trying to expand a DataFrame column with nested <code>struct</code> type (see below) to multiple columns. The Struct schema I'm working with looks something like <code>{"foo": 3, "bar": {"baz": 2}}</code>.</p>
  
  <p>Ideally, I'd like to expand the above into two columns (<code>"foo"</code> and <code>"bar.baz"</code>). However, when I tried using <code>.select("data.*")</code> (where <code>data</code> is the Struct column), I only get columns <code>foo</code> and <code>bar</code>, where <code>bar</code> is still a <code>struct</code>.</p>
  
  <p>Is there a way such that I can expand the Struct for both layers?</p>