I am using Auth0 for login in my Nodejs+MongoDB application. When user is authenticated, Auth0 provides user details such as name, email, nickname etc.(see attached screenshot) It also has one field called 

sub

 which is a unique identifier for that particular logged in user. Now I wanted to know should I store this 

sub

 field in mongo database schema for getting user specific data? for example if user creates some resources when logged In. Then while fetching data using /GET route I can use mongo query 

db.find({sub: xyz})

 and retrieve the data for that specific user. Is this correct implementation of storing

sub

field in database schema or do you think this can be improved? Please suggest thanks

Yup,

sub

is the user's id (as generated by auth0). You can also use a combination of

sub

+

email

.

So in my application there are posts which user creates. Now I have GET route for getting posts in that I am doing db.find({sub: xyz}) which returns all the posts for user with sub field having value xyz. Now I was thinking of another approach: when user login is success I will store user name, email, sub and _id (default created by mongodb) in mongodb user model. Now in post model I will have following fields: title, subtitle, and userId instead of sub field. Through this I can map user all the posts with specific user by userId. So in GET route I will do db.find({userId: userId}) instead of using sub field. Is this approach correct? Please suggest if this can be improved. Thanks

Yes, having your own ID for a user is better than relying on auth0 id. So in future you can swap out auth0 easily or add any other auth systems.

You mean to say if in future auth0 APIs change and they remove sub field or rename it then my application backend will break if I run all queries on sub field instead of userId is that right?