title: how to find document from collection by property name (NodeJS, Monggose)
body: <p>this is how my collection look like</p>
  
  <pre><code>{
      "field1": "aa",
      "field2": [
          {"field21": "bb"},
          {"field22": "cc"},
          {"field23": "dd"},
      ],
      "field3": "ee"
  }
  {
      "field1": "ff",
      "field2": [
          {"field21": "gg"},
          {"field22": "hh"},
          {"field23": "ii"},
      ],
      "field3": "jj"
  }
  {
      "field1": "kk",
      "field2": [
          {"field21": "aa"},
          {"field22": "mm"},
          {"field23": "nn"},
      ],
      "field3": "oo"
  }
  </code></pre>
  
  <p>what i want is find the document that the value contains "aa", so the document will be shown is first doc and third doc.</p>