title: MongoDB tabularize nested array
body: <p>Given the document of the following structure:</p>
  
  <pre><code>{
      username: "John",
      subjects: [
          {subjectName: "subjectA", status : "PASSED" },
          {subjectName: "subjectB", status : "PASSED" },
          {subjectName: "subjectC", status : "FAILED" }
      ]
  },
  {
      username: "Jason",
      subjects: [
          {subjectName: "subjectA", status : "PASSED" },
          {subjectName: "subjectB", status : "PASSED" },
          {subjectName: "subjectC", status : "FAILED" }
      ]
  }
  </code></pre>
  
  <p>How can I get all the passed subjects in the following format?</p>
  
  <pre><code>[{username: "John", subjectName: "subjectA", status : "PASSED"},
  {username: "John", subjectName: "subjectB", status : "PASSED"},
  {username: "Jason", subjectName: "subjectA", status : "PASSED"},
  {username: "Jason", subjectName: "subjectB", status : "PASSED"}]
  </code></pre>