CS50 2021 in HDR - Lecture 9 - Flask

This is CS50, Harvard University's Introduction to the intellectual enterprises of computer science and the art of programming. Enroll for free at cs50.edx.org/. Slides, source code, and more at cs50.harvard.edu/x. Playlist at • CS50 Lectures 2021 (HDR) .
TABLE OF CONTENTS
00:00:00 - Introduction
00:01:17 - Web Programming
00:02:29 - http-server
00:03:36 - Paths and Routes
00:06:01 - Flask
00:08:47 - app.py
00:20:11 - Forms
00:32:58 - Templates
00:41:10 - GET vs. POST
00:46:50 - Model, View, Controller
00:52:37 - froshims
00:58:49 - Form Validation
01:08:05 - CSS and Flask
01:10:29 - Jinja Loops
01:16:08 - Model
01:22:41 - SQLite and FLask
01:34:13 - Email
01:40:46 - Sessions and Cookies
01:47:58 - Login
01:54:24 - Shopping Cart
02:02:50 - Search
02:10:09 - JSON
02:15:18 - This was CS50
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LICENSE
CC BY-NC-SA 4.0
Creative Commons Attribution-NonCommercial-ShareAlike 4.0 International Public License
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David J. Malan
cs.harvard.edu/malan
[e-mail]

[@user-xr6sk5be8n]

Woooow! The difference between any tutorial and this video is the teaching professional.

[@AriaHarmony]

For anyone who's curios, the lightbulbs binary says

[@airepublic9864]

Few videos on youtube that you don,t need to listen with twice speed

[@sayori3939]

This lecture is pure madness

[@luv_sic]

Fun regardless

[@DeKu-rl5oy]

Just finished the Week 9 lecture and can't believe i'm now at week 9

[@juniorvalente1483]

me too

[@saadshah1035]

Excellent as always !

[@shivaprasad79999]

Guys, please make sure that you name the templates folder as "templates". It wont work if you name it as "template". We get error 500.

[@almutasim79]

omg this issue made me panic in pset9😂😂

[@sayori3939]

Just because you said please now i am not doing it! 😝😝 My program is not working 😢😢

[@lc93]

The Best Teacher in the world!!!

[@cristianmedina9630]

This was a lot, but I can't help loving it. So much fun.

[@Mamdouh_]

Best lecture ever. And seeing how teacher David deals with his mistakes is another level of teaching. The audience silence is driving me crazy 😠

[@DarkLightBoy]

They're not silent, we just can't hear them haha

[@pfever]

This was the best lecture!

[@abubakrmughal5938]

New and Improved!

[@davidx5828]

See how smart people with the name David are!

[@anuradhamangalpalli2774]

Wow! Amazing Professor. I am planning to enroll for CS 50

[@guillermoemmanuelsanchezin4068]

My brain hurts badly after watching this lecture, so much information for a noob xd

[@not_amanullah]

thanks ❤

[@alptug]

i made it this far!!!!!!!!!!!!!!!

[@rahulmittal9023]

Finally, dots are connected🧩

[@dakoderii4221]

Anyone know what theme David is using? That's the best light theme I've seen(for me anyways) but I can't find it. 😫🤷‍♂

[@Matiwan3]

this man is amazing

[@randlyce]

i'm lost in this one

[@e-raticartist]

1:58:20 I tried modifying the ids and my request works, they append to the session["cart"] even with a different id from the database. I think line 33 does nothing because it doesn't check if the key exists in the database, only if the id is None. By the way, it doesn't show a book with id 30, for example, because in line 38 we select books with ids 1 to 7. But I think we should stop before appending, am I wrong?

[@sayori3939]

You're write, the user can simply make up an id

[@mon0theist_tv]

It's kinda reassuring that when he asks the audience of students for answers, they have no idea either 😆 Really fascinating stuff though, I never realized that HTML was being dynamically generated

[@immanuelkantholz9033]

Admittedly I just started the video but in the first three quarters of an hour there was nothing that php couldn't do. I'm curious where the advantage of flask will be.

[@ago255]

Does anyone have any problems with the email part? When I ran flask, I keep getting keyError: 'MAIL_DEFAULT_SENDER'. I tweaked a few things like changing os.environ["MAIL_DEFAULT_SENDER"] to os.environ.get("MAIL_DEFAULT_SENDER"). Still getting the error default sender is not defined. Any solution? Thank you

[@sowki_tv]

This messing with HTML code reminds me of the times when I was changing the content of the Steam website to add a different amount of money to the wallet than the default 10, 20, 50 euros, etc. I don't know if the Steam people were so lazy to fix it, or if they just thought that if someone cares so much, they will just let them add an undefined amount to their wallet, after all, it's profit for them anyway

[@sabatv100]

Can split titles this video and other video as a C Lecture video?

[@adityagupta4074]

They will in some time

[@Madikon07]

Hey, an update they split titles

[@raicyceprine8953]

18:17 finally, this is answered😭 (the significance of 'question mark' in URL) but honestly it looks like he doesnt know the answer. He just answered out of spite of giving a satisfying answer😂 18:22 nvm. he actually did give a good answer here 1:02:03 wait, is /register actually supposed to be necessary or did we only changed it cause /greet was already used?? or are these routes actually supposed to be specific? in relation to file name or input tags? i m confuse 1:04:34 him making mistakes actually is effective for learning 1:17:02 i guessed it out of the blue to be 'empty dictionary',, i feel proud of little things😭 1:37:35 this is funny though😂 1:45:34 cookies compared to resort stamps 2:01:52 my question as to why he never used elif or else in these conditionals has finallly been answered finally done (July 16 2023)

[@amaldev4150]

same company of flask developed jinja! FYI

[@FatimaZahra-zb8ub]

please can someone explain to me what is happening here(1:23:39)? I am stuck at this point. like how do I create a database...

[@cabanis]

See lecture 7 - SQL.

[@sashildath4432]

2:12:33 how did the data get converted to json format. has anyone tried this?

[@mon0theist_tv]

because of the response.json() call at 2:13:20, whereas before it was response.txt() (I think)

[@sayori3939]

Wow every time there's less comments as the series goes on

[@varunnayyar3138]

Personal bookmark 55:00

[@sayori3939]

David making those mistakes makes me really nervous about pset9, does it hurt? 👉👈

[@sayori3939]

I completed it one week after, it was really good

[@sungvin]

@@sayori3939 Chad

[@sayori3939]

@@sungvin 😂😂😂 are you taking the course?

[@sungvin]

@@sayori3939 Yes :D I’m yet to start pset number 9

[@sayori3939]

@@sungvin :3

[@rayroman6209]

At first I did not intend to watch this as i thought it's another programming language, my mistake it is a python framework Did they abandon Django?

[@franciscogutierrezramirez5497]

i think they focus on django in their webdevelopment track, this is just the intro to CS

[@sonnetsoftheapocalypse]

@@franciscogutierrezramirez5497 are there videos on their web development track available?

[@airepublic9864]

Cause django need a full ist itself.

[@sayori3939]

@@sonnetsoftheapocalypse yes you can watch it here on cs50 channnel and edx

[@airepublic9864]

Python is awsome as f$k

[@sayori3939]

Ikr, what infuriates me is the people saying python sucks etc, complaining about it having a lot of libraries (as if it's a bad thing) and start defending languages like C which are much older and should have a lot of good resources for the time it has being around, they should start making it appealing for developers or shut their damn speaking hole and stop complaining about people using other languages

[@DogginsFroggins]

Great teaching style etc but this week is far far too condensed, this could be 2 or 3 weeks at least, its literally Web apps, extending layouts, sessions, a whole new type of syntax, integrating sql lite all in a 2 hour block with no practical input until after. I'm no teaching expert and I understand this it pique the curiosity of the student but it seems really overwhelming. Like its really hard to pay full attention when there is no way my short term memory can hold even a 10th of what is being shown here, because I know the real learning is me playing around with it myself.

[@sungvin]

Yeah, 8th and 9th weeks are so fast, like super sonic speed, even python section of cs50 didn't have that.

[@raicyceprine8953]

true, i cant watch the lectures straight but its also good for me to take a break every 5-10 mins

[@kamilp1567]

If you use ! shortcut for creating html layout template, delete or you'll get 500 error. Good luck!

[@mrCetus]

the video editors for this one were like: body {background-color: red; camera-noise: true; shadows: obliterated;;;}

[@krosskinetic]

I think it is because of HDR compatibility of this video. Like I have HDR certified phone and colors appeared great on it but on laptop it is a bit...off?

[@sayori3939]

There's a non hdr version on the channel

[@aliben123]

I feel like I have a lot of power and and i don't know what do with it hahz

[@Shalve94]

The secret message is

[@maximglebov7705]

Что с нами со всеми случилось? На сцене человек один, и вынужден быть в маске. Спасибо вам.

[@thuliocribe103]

wy you use maks??? give a tal for this man

[@cposadaa]

Seriusly..... WHY the mask ? What are you trying to prove ?

[@evilpimp7877]

I don't wear a mask personally but isn't this in Harvard? I'm sure they have a mask policy in their buildings? He is just following the rules of his job.

[@zionaea3094]

Because of COVID

[@exnihilonihilfit6316]

@@zionaea3094 You genius.

[@alsonyang230]

?

[@anniemeenie]

Why do you care so much?

[@ayeshaafzal7495]

1:03:52 I saw it the moment he typed sport in "request.form.get("sport")" at 59:43

[@magickpalms4025]

the video editors for this one were like: body {background-color: red; camera-noise: true; shadows: obliterated;;;}