finance check "handles valid ticker symbol" is actually using "invalid ticker symbol"

[goyalyashpal]

hi!

Reason behind

• i navigated to the git blame view of the file defining those checks:

• there were only 2 recent commits by @ CarterZenke & @ curiouskiwi which were very small

• navigating past them, i noticed that most of the checks defined there were written by @brianyu28 in month of 2020 November. https://github.com/cs50/problems/blame/bbc4dce5aad913a04fc2d6ff0092c3941d384616/finance/__init__.py#L90

• So, more than 3 years ago.

And it seems to me that:

• back then, the stock market api backend used was: the iexcloud.io i.e. the Data provided by IEX part in the distribution code of the layout.html

• ... and that iex provided example dummy requests similar to how visa has dummy cards in the credit pset, or the stripe payment gateway has dummy emails etc

• recently, the api backend was changed to yahoo finance; with which the dummy request no longer returns dummy data; but rather a 400

• but the checks description were not updated to match that. that's what caused the problem.

even the cs50's own implementation aka "staff solution" throws 400 error on running check50's data on it.

https://github.com/cs50/problems/assets/19423063/18b3fcd2-6b5b-42fe-9a32-ae82275dfe3d

details

• the check50 is using the value .quote("AAAA")
• which results in the helpers.lookup() url string to become:

https://query1.finance.yahoo.com//v7/finance/download/AAAA?period1=1703103695&period2=1703708495&interval=1d&events=history&includeAdjustedClose=true

• or as shown in the console logs, the HTTP GET request to be:

DEBUG: Starting new HTTPS connection (1): query1.finance.yahoo.com:443
DEBUG: https://query1.finance.yahoo.com:443 "GET /v7/finance/download/AAAA?period1=1703103695&period2=1703708495&interval=1d&events=history&includeAdjustedClose=true HTTP/1.1" 404 52

which

• being an invalid symbol, results in 404 from this yahoo api itself. and hence,
• both - my implementation, and even cs50's own implementation at https://finance.cs50.net/buy rightly show 400 on it

when given a genuinely valid symbol like nflx:

• the yahoo api responds with correct data, and again,
• both my as well as https://finance.cs50.net/buy show the data correctly.

now:

• if the ticker symbol is invalid/dummy,
• the upstream yahoo api doesn't have any data on it,
• so, how will any application show it as valid without comprimising with academic honesty 😃

https://github.com/cs50/problems/blob/5144d41e5cc83fe5708bfacce9f1811e897867c1/finance/__init__.py#L96C1-L105

[curiouskiwi]

@goyalyashpal what you may have missed is that check50 uses its own specific lookup.py file and does not use the Yahoo api at all. This is done so that we always know what the price will be. So we don't need any changes. Thanks for the effort though.

[goyalyashpal]

hi @curiouskiwi ! thanks a lot for sharing.

umh, my check50 report is failing. and i have now no clue why.

'cz as shown in above screen recording, both in browser & in console with http status 200 it is clearly working "on my system" lol

here's the link: https://submit.cs50.io/check50/8ee4ad64886dc4fac29728a853fe20be3d18a6aa

[curiouskiwi]

More than likely, you haven't formatted all dollar values using the usd jinja filter, as described in the first Hint in the specification. If that's not it, I'd suggest you post in one of our communities for further help.

[goyalyashpal]

ahwwww right. awesome. thanks a lot again.

edit: yeah, it passes now. thanks a lot

using the usd jinja filter, as described in the first Hint in the specification