title: Storing dynamic value in mongoDB which refers to other properties
body: <p>I am working in Node js - mongoDB . I have a requirement where I need to store and retrieve data in mongoDB which are dynamic and refers to other keys in the collection.
  Example:
  firstName : string
  lastName : string,
  fullName : string</p>
  <p>Assume we insert a record like below</p>
  <p>{
  firstName : &quot;hello&quot;,
  lastName : &quot;world&quot;,
  fullName : &quot; firstName lastName&quot;
  }</p>
  <p>Now when we retrieve the record the fullName field is expected to show the actual name . In front end , we could use something like string interpolation to achieve this in angular. Is there any way I can directly handle this expression in backend . My actual use case involves more complex structures hence it is not possible to rely on front end.</p>