Learn Flask for Python - Full Tutorial

Flask is a micro web framework written in Python. It is classified as a microframework because it does not require particular tools or libraries. Learn how to use it in this crash course tutorial.
💻Code: github.com/jakerieger/FlaskIn...
Tutorial from Jake Rieger. Check out his KZbin channel: / @codingwjake776
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Learn to code for free and get a developer job: www.freecodecamp.org
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[@BrentBrewington]

Love that you walk through completely end to end - from installing prerequisite tools all the way through. Sometimes the initial install/setup stuff is the hardest part

[@pavloaleksyeyev5065]

virtualenv install for windows 10: open up terminal in VS Code 1)pip install --upgrade virtualenv press enter 2) virtualenv env press enter 3) virtualenv \path\to\env\Scripts\activate press enter For windows 10 you must use 'virtualenv ...' to run commands. Example: 'virtualenv \path\to\env\bin\activate' to activate.

[@hassanwehbi6324]

habibi u saved my life

[@karthikpuvvula]

thank you !!

[@kunalrajput2234]

Thank you odin

[@No_name-lq2ww]

3) For windows 10 just run ' \path\to\env\bin\activate' without virualenv command

[@CozyCoupons_]

after that if you guys encounter any error like this (execution_policies or running scripts is disabled on this system) 1) use this commend: set-Executionpolicy -scope process -Executionpolicy Bypass run the above commend 2) after that use this commend: .\Activate (or) Activate

[@N3fario]

I like the pace and the fact that there's no fluff words. Though, this isn't really a 'learn Flask' video, this is a "Type as you follow along as he *kind of* explains what's going on" type video.

[@N3fario]

If your table is blank when you first make it, add a border=1 attribute to the table tag so,

[@cat47]

15 minutes in and he's already showing us how to work with databases. THIS GUY IS AWESOME

[@MeetSinojia7]

Exactly what I needed! Covers complete flask basics for a simple CRUD application (Todo list) in 45 minutes.

[@tiaantoinette8047]

The voice was instantly comforting - thank you for being my educator on flask in less than an hour!

[@danield.7359]

Great tutorial about a great framework. The video nudged me into the right direction. I just finished a contract management app for our leasing business within less than a week. Thanks!

[@CreativGaming]

Hello all. I figured out why this doesn't work. SQL alchemy has been updated since this video Tutorial. The problem is nobody explains it properly, but I will give you a quick fix. Instead of Running the db.create_all() command in the terminal Initialize the Database in your code after your Database Models classes have been setup: with app.app_context(): db.create_all() Basically, put this in your Flask app under the Db.Model classes. Make sure to indent properly and run your flask app one time. It should create the database (also check your instance folder for the db file). Then comment it out. You can run other SQL commands under the with statement if you need info on what's in your database file.

[@mohitvashisht9259]

This is not working for me. Can you share your code please. Thanks!

[@CreativGaming]

@@mohitvashisht9259 What error message are you getting?

[@mohitvashisht9259]

The database file is not creating while running the app.py file

[@CreativGaming]

@@mohitvashisht9259 Yes, but what error message are you getting in the terminal when you run the app.py file?

[@mohitvashisht9259]

@@CreativGaming No error in itself, it is executing and giving no error but my database file is not created, as shown here.

[@razvanc94]

Really nice tutorial. I'm a software developer who works in embedded systems/automotive and for my work I use C programming language for 99% of tasks and for the rest of tasks I use python. I enjoid this crash course.

[@jacobmoore8734]

Holy cow! This has been a lifesaver. I got about a quarter way through Cory Schafer's flask series and was completely lost. It's a bit hard to tell the essentials apart from stylistic design choices and I just felt like I was struggling to memorize huge chunks of code. This tutorial is way more bare bones; but that's a great advantage it has over other tutorials as I'm really getting the no-nonsense core ideas about flask out of this. Great stuff!

[@anyanyanyanya27]

Same

[@LamNguyen-nm1id]

Cory Schafer's flask series is something else, you should take your time taking it in. it's just that good

[@carlfranz6805]

Cory Schafer is pretty good. His downfall is that he talks way to fast and he skips steps. Also, I'm using a 32 inch screen and even then his VSCode display is still sometimes to small to read clearly. He also needs to do more illustrations, especially project structure. In any of these APIs, the project structure is very important to success AND understanding. It doesn't hemp that VSCode's method of displaying directory structure is less then optimal (read as 'stupidly bad'). Try running it at 0.75 speed. I find it helps with many of the tutorials available on KZbin. Also make sure KZbin is sending the highest available video quality. I'm regularly going into the settings and changing it back to 1080p (this really helps reading small print even on a large screen). I sometimes wonder whether having two screens would help doing these tutorials.

[@kristerl939]

Thanks, this was exactly what I needed to get going with flask :)

[@MickaelGillot]

Thanks a lot, it was truly enjoyable to follow your tutorial step by step to dive into Flask. Your voice is really nice to hear. Now, I feel like I have all the basics to build my own app. You did a great job.

[@arturoroche3782]

08:53 render_template 10:02 template inheritance 12:58 CSS 15:36 SQL Alchemy 20:35 div 22:25 Make a textbox and a button 24:50 Methods

[@davinsutanto]

OK

[@marmeladovsvid]

"20:35 div" HAHAHAHHA bro

[@sam031000]

This is a god send! Have a task using Flask and struggled for 2 weeks just to setup the virtual environment, thanks so much :) Liked and subbed!

[@DouglasFrota]

Great tutorial, my friend! I have some experience with Django and yesterday I had to to build a simple crud application and Flask fitted well. Keep it up! 😁

[@someoneokay5530]

Really good tutorial. I am a beginner in flask and I must say the lecture is really insightful covering all the topics in one go.

[@lazyguy597]

NA..

[@user-bm8uc1ei5p]

Wow, it was so easy explained. I believed that the topic is really difficult, but thanks to you, I understood everything. Thank you!

[@TechWithTim]

Congrats on 1 million subs!

[@Crucizer]

and no one recognized you here?

[@jheave]

Hi tim

[@kromydas5063]

hi tim your tutorials are so nice :)⠀⠀⠀⠀⠀⠀ ⣰⣿⣿⣿⣿⢢⣶⣄⡀⁣ ⠀⠀⠀⠀⣀⣐⠻⣿⣿⡿⢣⣿⣿⣿⣿⡆⁣ ⠀⠀⠀⣰⣿⣿⣿⣶⣍⡁⢿⣿⣿⣿⡟⣰⣷⣄⁣ ⠀⠀⣴⣿⣿⣿⣿⣿⣿⣿⣷⡮⣿⢏⣼⣿⣿⣿⣷⁣ ⠀⣼⣿⣿⣿⣿⡟⠿⣿⣿⠟⠁⢋⣾⣿⣿⣿⡟⣱⣦⡀⁣ ⣼⣿⣿⣿⣿⣿⣁⠀⠀⠀⠀⠀⣿⣿⣿⡿⢋⣾⣿⣿⣿⁣ ⠘⣿⣿⣿⣿⣿⣿⣷⣄⠀⠀⠀⠈⠻⠟⣵⣿⣿⣿⢟⠁⁣ ⠀⠈⢿⣿⣿⣿⣿⣿⣿⣷⡀⠀⠀⠀⠈⠻⣿⠟⣡⣿⁣ ⠀⠀⠈⢻⣿⣿⣿⣿⣿⣿⣿⡀⠀⣿⣶⣤⣠⣾⣿⡟⁣ ⠀⠀⠀⠀⠻⣿⣿⣿⣿⣿⣿⣷⢠⣿⣿⣿⣿⣿⡟⁣ ⠀⠀⠀⠀⠀⠹⣿⣿⣿⣿⣿⣿⣾⣿⣿⣿⣿⡿⠁⁣ ⠀⠀⠀⠀⠀⠀⢸⣿⣿⣿⢿⣿⣿⣿⣿⣿⣿⠁⁣ ⠀⠀⠀⠀⠀⠀⣼⣿⣿⣿⣷⡌⢉⣽⣿⣿⡇⁣ ⠀⠀⠀⠀⠀⠀⣿⣿⣿⣿⣿⡇⣸⣿⣿⣿⡇⁣ ⠀⠀⠀⠀⠀ ⣿⣿⣿⣿⣿⣷⣿⣿⣿⣿⡇⁣ ⠀⠀⠀⠀⠀ ⣿⣿⣿⣿⣿⣿⣿⣿⣿⣿⡇ (edit) : thx for 2 likes I never got a like before :))))))))

[@senthilkumarsundaravinayag9809]

Alert everybody The big Tim guy is HERE!!!!

[@vikalpjain1098]

Just subscribed because of Tim

[@wahedshuvo]

Finally, I could really learn something on the web! You are an amazing educator!

[@jackcardozo]

Glad I stumbled on your tutorial. I followed along for a couple of hours. Thanks so much!

[@490o]

I'm just starting Python and I'm already loving this language. This is so much more fun than PHP.

[@DominicNweze]

python is the best. 😊😊

[@theonlycaulfield]

That's kind-of a low bar. Anything is better than php.

[@jasonlee6294]

Awesome, awesome. as an experienced developer, I could learn new stuff with your confident voice. Thank you, Dude

[@alexkarav]

It's a really cool lesson. Every material, like books and video lessons, show how to create a blog, a nothing else. And this video is something special, thank You so much!

[@anisbhsl]

Went through the full video. Good intro for newcomers! Thank you!

[@circuitmasters5258]

Brother This is what I needed..I got tons applications I am ready to deploy!

[@darwishds1459]

" Error while activating virtual environment in Windows 10 PowerShell " ??? If you are running Windows, then navigate to \Scripts, where is the name of your virtual environment. Then, execute the following command: set-Executionpolicy -Executionpolicy Remotesigned -Scope CurrentUser Type activate and press return. You will now be able to use your virtual environment.

[@oferl15]

not working from cmd. Open Powershell as Administrator and run the command: it works

[@snigdhapeddi8528]

@@oferl15 after routing to the above mentioned path type in .\activate in VS code terminal to activate the environment

[@alexandermarthius5593]

the fastest and easiest way for my first introdutions flask python.. you doing a great jobs jakerieger! Thanks you so much...

[@bipulkumar1556]

This is amazing for a python experienced person, what is wanted to learn only how to quick started with flask.

[@Kenobiii]

Great tutorial! A lot of densly packed information for a person who is not that familiar with web applications, but I already learned a lot in this tutorial!

[@lron1447]

Thank you very much. It was indeed a great course. I was able to overview the connections between Python, Flask, CSS and SQL.

[@RobertoTucci]

thanks man, that has been my official introduction to Python and Flask! You rock!

[@CTYPCL]

this is an incredibly simple and useful tutorial, thank you very, very much

[@EdiFerreiranet]

Loved when you did open your Chrome and I saw that you are a PIRATE!!! :P

[@da_winraja9740]

anyone having problem with the source command remember you just need to put in the location of activate.bat file, usually in the env directory.

[@KimiaXLife]

This was an amazing thorough tutorial! THANK YOU!

[@sknganga3633]

first freecode camp tutorial i have ever finished!

[@BRBallin1]

By far one of the best frameworks I used built in the most elegant programming language. Building REST APIs has never been easier.

[@sfsf285]

How is it the best by far? If anything its just a little small framework

[@juanfolgarcolomer2573]

This tutorial is simply genius mate, you not only explain the very basics from a Flask app but the actual deployment to Heroku too. Probably one of best tutorials ever. Respect!

[@GerardGRes]

Wait, he is setting up an entire database like do this than that than that. I dont call that explaining, feels moren like a demonstration

[@lycorislune3846]

@@GerardGRes right? I felt like he could've explained more

[@mrcrazyenough007]

I have been working on different frameworks from different languages from the past 8 years. When it was PHP, I worked with CodeIgniter, Symfony, Laravel, Yii2 and CakePHP When it was NodeJs, I worked with ExpressJS, KoaJS, SailsJS and NestJS and now I got a new Python project and the requirement was Flask This crash course helped me a lot in kickstarting with Flask in no time, and definitely this crash course is mostly intended for experienced developers only.

[@lukeverso]

Such a cool tutorial, finally one short and complete!

[@bulcub]

This really filled in some missing blanks, especially on how to setup in Visual Studio Code. Thanks

[@greensphinx]

I need this: 15:53 30:45 42:40 Finished :) Good tutorial

[@unknownvariant9842]

Pretty darn good tutorial. It helped a lot. Thanks for taking your time to make this.

[@ramankumar41]

The perfect hands-on intro to flask !!

[@mastercode7851]

i just love your vscode setup the font and everything is unique

[@byeCoDhelloRS]

Hey all, I was having difficulty with my CSS not loading even after I updated it. The solution is to hard refresh because for some reason flask will save your style settings with caching. Try CTRL-Shift-R and hopefully that can solve your issue as well. :-)

[@user-qy7dc3oq2i]

I guess it's not a Flask issue, but rather your browser is actually doing that caching stuff.

[@MeetSinojia7]

Thanks, I was confused by this behavior. Your comment saved me the time to debug it :)

[@civ20]

Has nothing to do with Flask, it is your browser that is caching the website files.

[@_JoeDigital]

THANK YOU! Great info

[@georgigeorgiev271]

Thank you a lot!

[@ilkerozturk3260]

Thanks Jake, it was so useful for me to learn basics of flask 🙏

[@LS-cb7lg]

amazing workflow i dont know how you can be so fast! amazing tutorial too thanks a lot!

[@podoliev]

Thanks a lot, this is an amazing tutorial! I highly recommend it to everybody;)

[@yashsolanki069]

Congratulations team #freecodecamp on reaching 1 Million milestone !🙌

[@mayursawarkar7916]

Good example and simple steps that one can follow along. I'm able to create that Task Master. Kudos to you! Thanks!

[@juanmachatelet]

This video really helped me to get started with Flask. Thank you!

[@sushantdas1349]

Pretty good tutorial, although it can be a little too fast for a beginner with no backend experience. But for switching frameworks, this is really good. :)

[@spicymercedes5287]

agree

[@deaththink]

pause or use the .5 speed and or cc. thats what I do.

[@catherinemamo6837]

I agree, but otherwise a very good one.

[@AudreyGraceB]

As a beginner, it doesn't explain anything...

[@circrna]

Excellent! 6:04 Install Requirements 6:53 First app 8:55 Static content, introduction 13:00 CSS 15:36 Databases 19:38 Setting up a database (use 'flask shell' at terminal to activate interactive shell if running it from terminal). And run the commands there. 22:19 Adding methods to 'route' in app file 34:00 Delete code is done; Updating code start here.

[@rodrigomessias]

Thanks for the explanation about Flask, it helped me a lot to understand several concepts.

[@iainlindahl8460]

That was so helpful, thank you! Got me going in Flask

[@albertulysses]

Thanks for the tutorial, I'm working through the Flask Mega-Tutorial right now as well and your video really helped me understand some of the things I didn't catch on his tutorial. For example, the difference between {{}} and {%%} for Jinja

[@quanganhbui9503]

I'm stupid so I'm still not sure, what's the difference , can you help me, please ?

[@albertulysses]

@@quanganhbui9503 sure what isnt that you don't understand?

[@quanganhbui9503]

Albert Chavez the 2 brackets you mentioned above

[@albertulysses]

@@quanganhbui9503 {%%} are statements for "for, ifs, and loops"and {{}} is to out put something. If you're familiar with python, when you write a for loop you have to write "for x in y: return x" here it's "{% for x in y%} {{ x }} {% endfor%} " of course this isn't a functional language, so it's not exactly used the same way but the concept is similar

[@anupthatal5253]

Which flask mega tutorial you are using

[@lhayanavieira7723]

for those who are having the database creating problem: just delete the "completed = db.Column(db.Integer, default = 0)" line so it's gonna work

[@niteshsingh561]

Still not working for me

[@namegoeshere657]

Amazing tutorial! BEST beginner flask tutorial out there!!

[@jannikbade5974]

very nice to show the final result at the beginning of the video! 👍🏼

[@issygaming5479]

You guys almost reached 1 million subscribers 😎

[@OttoFazzl]

1.1 already!

[@kokowin5851]

If you are not getting a lines to separate rows and columns like he did you can simply add this:

[@pawnage3]

Any idea how he got the lines without adding this? Also, thanks for posting this!

[@natashaiggwilv7193]

@@pawnage3 different browser probably, others had the same issue only on Chrome and Firefox

[@ysq-nomi]

Great video, to the point. Exactly what I was looking for!

[@david2beckham691]

Very simple and excellent tutorial for getting started with Flask

[@ayubomaraden867]

while i was watching this video you reached 1m subs :))

[@destinyjames6117]

Tip: On windows dont put activate.bat, just do activate in command prompt. Note that the privacy issue or something does not allow this to be done in VSC in terminal.

[@hardikjadwani7715]

Thanks a lot :)

[@jakubunold5750]

Very good tutorial. Helped me a lot and took several days to fully understand :P

[@umeshpandey5226]

Incredible simple and precise flask tutorial !!! Hatts of you 💕👨‍🏫📓

[@sweetphilly2]

Heads up: if you plan on using conda to perform this tutorial, make sure you're using pip to install these packages; otherwise, you may run into an issue with the packages in requirements.txt pointing to the conda installation of the package. You'll experience a "No such file or directory" error during the push to master.

[@franciscobacotich2672]

og

[@atibyte]

I learnt a lot, thank you.

[@sivaramanramamoorthy8493]

really

[@namratabafna14]

Simple and to the point tutorial!

[@izzlenizzle]

Simple and eloquent crud app tutorial. Nicely done!

[@mdhidayat1117]

if you have Windows and getting errors while activating a new virtual env, try this ".\env\Scripts\activate " and ".\env\Scripts\activate.bat " instead of "source env/bin/activate".. one of them will work. first one worked for me, latter didn't.

[@_s._.unshine]

YOU ARE MY HERO

[@natashaferguson1618]

If you are on Windows, activate your virtual environment with env/Scripts/activate

[@NikkiMcMistie]

Love it. Smooth and quick. Good framework

[@petera.k.8735]

Great stuff, all I needed to know in less then an hour.

[@Omkarh]

I am stuck on 20:02 when I type "from app import db" in terminal it is showing this "TypeError: Additional arguments should be named _, got 'defult'"

[@sylwesteroleszek3143]

You need to install flask-sqlalchemy. It looks like you have SQLAlchemy installed but not the Flask extension. Try pip install Flask-SQLAlchemy in your project's virtualenv to install it from PyPI.

[@goddessleader]

@@sylwesteroleszek3143 Thank you!

[@spaghetti534]

@@sylwesteroleszek3143 thanks

[@dotterel]

legend, bruv

[@StefanosStavropoulos]

Nice tutorial, thank you! I'm getting the error "Instance of 'SQLAlchemy' has no 'Column' member " when I try to add id variable under class Todo(db.Model). SQLAlchemy is imported though. Any ideas?

[@darioradic117]

The following info from StackOverflow resolved the same problem for me: pip install pylint-flask on your project directory find folder .vscode (if you dont have it, just create it) inside settings.json add this line { "python.linting.pylintArgs": [ "--load-plugins", "pylint-flask" ] }

[@carlosamaral6917]

@K Mmm I have the same problem as well. In both Vscode and pycharm

[@sakshishetty1310]

@@darioradic117 I added that but still getting the error

[@athegreat88]

CTRL+SHIFT+P select linter disable linter. Restart VS code that solved my problem.

[@tayebshahbakhsh]

Thank you for this wonderful tutorial.

[@noahplant4524]

This was exactly what I needed very much appreciated

[@CdGreven]

FYI (if anyone encounters the same problem) I was using comment blocks inside html files to take notes but jinja did not like it. Deleting the comment blocks inside html solved them.

[@JorgeGarcia-fv3gp]

That font is beautiful! Whats it called?

[@IzzyRock]

OMG thank you so much for this video! One of the best and easy to follow tutorials. Appreciate it very much.. thanks again!

[@cindinishimoto9528]

I'm so happy I just got my first web app using flask!! Thanks, man!

[@guillermobarboza5903]

Hey, when linking my css to base.html, I href="/static/css/main.css" and it applied my styles! is Jinja necesary?

[@johnnylang3657]

yeah, coz your dev env is probably different from the published one once the project is deployed to application server, so there might chances the hard coded css path is not gonna work

[@jakubunold5750]

Yeah, I just had problem with it. Once it's hardcoded it seems not to accomodate to changes

[@timotheospetros]

How do Windows users install Flask and SqlAlchemy to their newly activated environment?? When I follow the instructions here, these packages get installed to my global Python37 folder instead. I wish Python were a little more Windows-friendly :(

[@AdalV51]

Great tutorial for Flask introduction, amazing content!

[@CaptainInbox]

great video. attractive due to the 1 hour time on it. Did it on windows in VScode, deployment it didn't go to plan every time, a fair bit of googling, took a few goes but got there, then did it again with a conda env, learned a lot. thanks.

[@sarathkumar-ie5iu]

what does this mean '' % self.id? Why is it enclosed in a tag and what does the percentage mean?

[@ARKSYN]

All that line does is return a printable representation of the Todo class we created. The percent is Python syntax for string interpolation where '%r' is the placeholder and the '% self.id' is what will replace the '%r'. In this case we're just printing: where id is the id of the Todo object we just created. The brackets are just for formatting they aren't necessary.

[@sarathkumar-ie5iu]

@@ARKSYN Thank you the brackets confused me

[@kelvinomereshone3541]

Percentages are Jinja2 syntax

[@Lucaischz]

I actually think it would be better to use __str__() other than __repr__() as it's not going to be the exact representation of the class, which should be Todo().

[@kken8766]

Hi, thanks for the tutorial. Good that finally someone can explain why we need the virtual env. I have a question. If I already created/established a database in MySQL. do I still have to go through the process of what you did on the class Todo(db.Model) part 17:45 where you build the DB in the python class? If so, is there a better way of doing this because I have 25 tables in my relational DB and each with 10+ attributes.

[@avinashchaudhary2374]

No you have to do it in any db

[@taruchitgoyal3735]

Amazing course. Allows to learn Python, Flask and build CRUD application.

[@xanthe69]

the best and easiest flask tutorial I have ever seen

[@KetanLambat]

If the css content is not loading, try refreshing the browser cache

[@stefanbaumann7474]

THANKS

[@corlipr]

Hey Jake, I've been following along in the video, and I haven't been able to see the CSS rules apply, is there anything I am specifically doing wrong?

[@ARKSYN]

How are you linking your stylesheet? Have you compared your code to the code in the repo for this video?

[@arturblachnio6210]

After changing css file, you need to 'refresh' your browser with ctrl+shift+r. Then you should see the changes.

[@aeddwad]

@@arturblachnio6210 Thank you so much! Do you know what is the difference between ctrl+shift+r and just ctrl+r?

[@LIGHTENING110]

@@aeddwad ctrl+shift+r clears the cache files as well. ctrl+r only reloads the webpage but does not refresh the linked files.

[@QuiqueFlowers]

The tutorial is very useful, thank you for share it :)

[@mgori_media]

wow. what such clear and very insightful intro to Flask. Keepup

[@shervinrad100]

I get an error at 20:00 because ImportError: DLL load failed: The specified module could not be found. line 27, in from _sqlite3 import *?

[@cosmicvoice7657]

good

[@spezistyle]

I'm on Windows and having problem creating that procfile ('Push failed: cannot parse Procfile.'). Any help how to create that empty file?

[@MilkJug12]

Tip, if you encounter a issue with return_template is undefined, make sure at the top where the from flask import Flask, do from flask import Flask, return_template.

[@DerSpielerMabuse]

Fantastic to the point tutorial. Brilliant