Store _Id as object or string in MongoDB?

Question

I am developing an API using Codeigniter and MongoDB. In this system I am saving the full name and _ID of users that the selected user is following.

What is best to

Answer 1

When you use ObjectId, it generates _id as a unique value in all your computers. So if you use Sharding, you will not worry about you _id conflicts. See how ObjectId generates in specification
But if you use string, you should generate it carefully.