Here is a full walkthrough for the Exercise Tracker project.

I connect to a MongoDB database and set up 2 models for storing users and exercise sessions. Then express routes can be created to add and retrieve data from the database which the user can access through form POST and url GET routes.

Input data of username: POST /api/users
Input data of exercises: POST /api/users/:_id/exercises
GET a list of all users: GET /api/users
GET user's exercise log: GET /api/users/:_id/logs