title: How to update array value in MongoDb
body: <p>$set is overtiring complete array value how to update it </p>
  
  <pre><code>                var obj = // contains some other data to update as well 
                  obj.images=images;  //  updating obj with images []
                  Units.update({_id: 'id', {$set: obj});
  </code></pre>
  
  <p>finally my  mongo object must be something like this  </p>
  
  <pre><code>{
  "_id" : "ZhBgrNFtr2LRPkQrZ",
  "sitouts" : "test",
  "interiors" : "test",
  "features" : "test",
  "keyHolder" : "test",
  "images" : [
      "1445481257465-8678-20130520_113154.jpg", ## `updated value ` ##
      "1445481257456-3-20130520_113157.jpg",
      "1445481258058-5771-20130520_113202.jpg",
      "1445481258230-9603-20130521_075648.jpg"
  ]
  </code></pre>
  
  <p>}</p>