Exercise 2: Why .slice(0, 10) Is Needed Here and Not in the Sibling — Possible Solution
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WHAT EACH DASHBOARD ACTUALLY RECEIVES
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The sibling course's expiry_date column is plain TEXT, and
better-sqlite3 hands back exactly what's stored - a simple string like
"2026-09-01", with nothing added or changed. That string is already in
the exact shape a dashboard would want to display.

This course's expiryDate field is typed DateTime. When Prisma Client
reads it, it comes back as a real JavaScript Date object on the server.
Express's res.json() then serializes that Date object to JSON - and a
JS Date always serializes to a complete ISO-8601 timestamp, including a
time component and timezone marker, something like
"2026-09-01T00:00:00.000Z", never just the date portion alone.

WHY THE FIX IS NEEDED
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Displaying item.expiryDate directly in this course would show that
entire timestamp string to the user, time component and all - not what
a "expires on this date" label should look like. item.expiryDate.slice
(0, 10) takes just the first ten characters, which for an ISO-8601
string is exactly the YYYY-MM-DD date portion, giving a clean result
comparable to what the sibling course already had for free.

WHY THIS WORKS AS AN ANSWER
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It correctly explains that the underlying values are different kinds
of things by the time they reach the frontend - a plain stored string
versus a Date object forced through JSON's own date-serialization
behavior - rather than describing this as an arbitrary or unexplained
difference between the two courses.