Exercise Tracker - Tips and Tricks

I recently completed the Exercise Tracker and spent a fair amount of time thrashing which, based on other comments here, is not uncommon. The User Stories for this project are poorly written and the tests are notoriously vague. I figured I’d share my learnings to possibly help out the next folks who attempt this one.

Mongo Schema

  • Mongo automatically adds Versioning (__v) and id fields unless you explicitly disable them. Having these present will potentially break test 4 if you’re returning the Mongo Model directly.


Parameters are not always passed in the URL. For the example, the HTML based schema exerciser uses a form with a POST query which sends empty fields as blank. The tests do not send a blank parameter when they do a GET/POST. This means that you need to both check to see if the parameter exists AND if it is blank before using it.

Review the Tests

The tests can be found here:

Understanding them can help fill in the user stories and save you time and heartache.

Test 4

The expected result must match this exactly:

const expected = {
     description: 'test',
     duration: 60,
     date: 'Mon Jan 01 1990'

duration must be a number.
date is the output from JavaScript’s Date.prototype.toDateString(). You will need to transform the date stored by Mongodb. Note also that if your node.js environment has a timezone other than UTC, toDateString() will modify the date. I suggest moment.js as a library to simplify modifying/outputing dates.

Test 6


It is possible to filter and limit the log portion of your User Schema using MongoDB’s aggregate queries. You can build a $project statement using the $filter and $slice aggregate functions respectively. You will need to pass in a JS Date object when constructing the $filter for the date. You may also need to $and the to and from conditions together.

Alternatively, just use JavaScript array manipulation to get the same result. My preference long term would be to use the in-engine manipulation, since it is likely to be more performant and scale better. Consider the case where you had many thousands of results - it’s going to be faster to NOT send them over the network from your DB to Node then hold them in memory to filter.


The result of Test 6 should be a single user object, not an array. It will contain an array however.

Testing and Debugging

The tests are run client side, which means that regardless of where you’re hosting/developing, you can run the tests so long as your computer has access to the URL. I was able to test with a localhost:3000 address.

Because the tests are occurring in-browser, you can view the browser console Network tab to see what is being sent and what is being returned. This, in conjunction with server side console.log statements will give you good insight as to what is being sent and received by the tests.

Happy Coding, Stay Safe!