using custom object ID with mongoose

I am working on a API.I am using mongo DB and mongoose as ORM tool with express. I want to use customer object id for my schema.

I want to implement CURD operation on the schema with customer id. The custom id can be anything for ex: 'someid' or a Number like 1.

The users can query the API using those Id's

I am using Model.create() method to insert and update() method to update and remove() method to delete and findById to find by id

The Schema is defined as

var mySchema = new Schema({
    name : {type: String},
    email: {type : String}
});

EDIT: If the ID is not present then generate an auto id