title: change _id string to base64 encoded string in mongodb via mongoose
body: <p>By default mongodb generates some random string like <code>5548087025c7f79259525eff</code> its type is ObjectId. Instead of that random string i want to use base64 encoded string so that it will always start from <code>alphabet</code> because I want CRUD on embeded documents which is not possible if id starts from integer according to my understanding. also store as string instead of ObjectId. Better if solution is using mongoose.</p>
  
  <p>I can encode string to base64 using nodejs as in my case. but i dont know where to change this default behavior ... thanks a lot</p>