db.createUser() in mongodb

createUser(user, writeConcern?)

This method creates a new user for the database where the method runs. db.createUser() returns a duplicate user error if the user already exists on the database.

The following operation creates the dbUser in the database and gives the user the readWrite and dbAdmin roles.

use db

db.createUser({

  user: "dbUser",

  pwd: "password",

  roles: [ "readWrite", "dbAdmin" ]

})

Approach 1: When  user is not exist

MongoDB

db.createUser({
        user: "dbUser",
        pwd: "password",
        roles: [ "readWrite", "dbAdmin" ]
      })

Output:

Successfully added user: { "user" : "dbUser", "roles" : [ "readWrite", "dbAdmin" ] }

Approach 2: When the user already exists

MongoDB

db.createUser({
        user: "dbUser",
        pwd: "password",
        roles: [ "readWrite", "dbAdmin" ]
      })

Output:

uncaught exception: Error: couldn't add user: User "dbUser@products" already exists :
_getErrorWithCode@src/mongo/shell/utils.js:25:13
DB.prototype.createUser@src/mongo/shell/db.js:1367:11
@(shell):1:1