This function solves an issue i was experiencing on a project where mongoose wasn't correctly returning an object for graphql resolvers. This fixes that issue by returning a new version of the object supplied to the function and converting the object id to a string.

objectify.js

//long version
const objectify = object => (
  object.isArray() 
  ? 
  object.map(element => objectify(element)) 
  : 
  ({
    ...object.toObject(), 
     _id: object._id.toString(),
  }) 
);

//Short, better version
const objectify = o => (o.isArray()?o.map(e => objectify(e)):({...o.toObject(),_id:o._id.toString()}));