title: How to findAndModify a value in a nested array
body: <p>Below is an example document.</p>
  
  <pre><code>    {
          "_id" : ...,
          "inprogress" : true,
          "name" : "Biz report",
   "inviteCode" : [
           {
                   "key" : "4fbd2b4b265a3",
                   "status" : "1"
           },
           {
                   "key" : "4fbd2b4b265b5",
                   "status" : "1"
           },
           {
                   "key" : "4fbd2b4b265b9",
                   "status" : "1"
           },
           {
                   "key" : "4fbd2b4b265bc",
                   "status" : "1"
           },
           {
                   "key" : "4fbd2b4b265c0",
                   "status" : "1"
           }
   ]
      }
  </code></pre>
  
  <p>According to the doc, I can use a modifier object as update argument, but it seems that an update argument doesn't include an filter on witch field I want to update. I can only use <code>$set:{name:"xxx"}</code> but I can't specify which element to update in a nested array. How do i set the "status" filed of the inviteCode column where key is "4fbd2b4b265a3"?</p>