title: MongoDB - Update an object in nested Array
body: <pre><code>{
    "_id": "xPBc4By8FemDwTPqH",
    "u": {
      "_id": "6PoZawHZcQz4Gwzcv",
      "username": "michael"
    },
    "friends": [
      {
        "u": {
          "_id": "eGqDjAjjtYADbuSnn",
          "username": "michael",
          "name": "michael"
        }
      },
      {
        "u": {
          "_id": "k4gKCGwYryXDMMHvs",
          "username": "joyce",
          "name": "joyce"
        }
      }
    ]
  }
  </code></pre>
  
  <p>I want to update the name of "friends.u.username": "michael" 's name is "hello", how I need to do it.</p>