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REST API With Flask & SQL Alchemy
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- Опубликовано: 14 авг 2024
- In this project we will use Python Flask along with SQL Alchemy and Marshmallow to create a RESTful API for products.
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0:27 - Intro to tutorial
1:00 - Intro to the other packages used in this tutorial (SQLAlchemy, Marshmallow, PostMan)
2:01 - Creating virtual environment (Pipenv)
3:09 - Installing dependencies
4:10 - Create main file (app.py)
5:43 - Initialize flask and run server
7:02 - Creating a basic route
7:58 - Making POST request in Postman
8:18 - Setting up database URI
9:04 - Setting up database
10:46 - Initialize database
11:00 - Initialize Marshmallow
11:23 - Creating a class for your resource(s)
16:13 - Creating a product schema (This is where we use Marshmallow)
17:13 - Initialize schema
17:56 - Another schema initialization
18:50 - Creating the database
20:04 - Creating our routes
20:15 - "Create a product" route ('/product')
23:30 - Making a POST request in Postman
24:50 - Creating "fetch all products" route
25:40 - SQLAlchemy .all() method
26:46 - Testing get all products in Postman
27:28 - Creating "get single product" route
29:29 - Creating "update a product" route
31:35 - Making a PUT request to product in Postman
32:21 - Create a delete route
33:49 - Making a DELETE request in Postman
Everything is easy if you put them in a single module, you should organise your app in a proper structure and then explain what you are doing.
If when running "db.create_all()" from the Python interpreter you experience "RuntimeError: Working outside of application context.", instead run the following three lines:
>>> from app import app, db
>>> app.app_context().push()
>>> db.create_all()
was looking for this. thanks sm
thanks!!
really thanks
instead you can ad a line of code in you app.py file "# Create all tables within the application context
with app.app_context():
db.create_all()
"
Another great video thank you.
If anyone gets the error "AttributeError: 'list' object has no attribute 'data'", it's because since Marshmallow v3 you don't need the .data attribute as dump returns the data directly ...
def get_products():
all_products = Product.query.all()
result = products_schema.dump(all_products)
return jsonify(result)
Thank you.
Just for someone who gets stuck when they get all products, the "result" variable will be default be an array/list so you don't need the `data` you can just jsonify(result)
For people coming across this video in June 2021. I had a few issues using the latest versions of everything.
1. At 18 minutes the schema no longer requires strict = True.
2. At 16.30, result.data should be result.
legend, thanks
For anyone using this now, and update to Marshmallow (from documentation):
Setting the strict option on class Meta has no effect on Schema behavior. Passing strict=True or strict=False to the Schema constructor will raise a TypeError.
Thanks bro.
legend, thanks
yeah i got it and removed it
Quite old, some methods are not the same right now. But it's definitely a good tutorial.
The strict param is not accepted right now for marshmallow (product(s)_schema)
For the get_all the following lines are the new ones:
all_products = Product.query.all()
return products_schema.jsonify(all_products)
Thank you so much, it saved a lot of time
Also, could you tell if dump() is depreciated?
thanks man
Thanks for the video Brad. kudos.
I was getting this error when sending a GET to return all the Products,
To fix it I returned jsonify(result) instead of jsonify(result.data)
I hope it will save someone else time
=)
Came here to find this exact problem
this solved my issue too of not finding 'data'
This was my last issue with the code. Thanks.
I was just about to comment this myself. Cheers!
You save my time, thanks
This channel is the gift that keeps giving.
Make sure you give back ;)
Thank you for presenting an example by using my favorite two tools - pipenv and vscode. They save so much time and effort. I also ALWAYS create a git repository for projects, even if they are the throwaway kind. As of this date, marshmallow is version 3.0 and the "strict" key is no longer needed or allowed.
Hi Traversy, Thanks so much for this video. I had been reading a lot and trying to get the concept of such an API but it was confusing to me mostly because many tutorials start off by putting different things in different files and then they import different modules into each other-it's just too confusing for a beginner. So thanks to God you put everything in a single file and gave us an overview. You have no idea how that is important to me.
Still useful in 2022. Thanks so much for this tutorial. I can't believe how easy this was to implement.
Thank you! I’m coming from node web backends and just tryna switch it up and start using python instead. Most tutorials were just brushing over the basics without explaining and getting straight to the point. Thank you brad, you’re THE best!
18:00 - When initialising the schema object, the strict argument is no longer valid, for the newer versions of SQLAlchemy.
Thank you very much for that. I removed strict=True for now
Hi, am getting an error, (TypeError: __init__() got an unexpected keyword argument 'strict') any advice
Got same errors too. I removed 'strict' and it worked.
Also getting this error, anyone know why?
@@johnnysim1985 new version release. Schemas are always strict so no need.
CzemBri ;p
@@KushChoudhary Thanks
For anyone confused about how the table name is generated, I just realized that on executing the db.create_all() command, a table with same name as the lower cased Class name gets created in SQLite database, so in this case a table named 'product' is created with the defined schema. Also, if Class name has a name like MyProduct then table would be named as my_product.
Awesome tutorial, it clearly shows why Flask is the best framework for python API development.
You can also use Flask-Restful to define your endpoints.
It give you all the HTTP verbs ready, your endpoints will be called resources rather than routes.
Thanks Brad for your hard work and dedication.
I was introduced to FastAPI and never want to look back! It feels like a sucessor to flask: inspired by it, but adding a lot of structure and validation with parameters and type hints.
Thanks for a quick introduction to Flask REST API. I am working on a React/Flask application for IT Inventory system. I was looking for something quick on Flask REST API development.
Is this some sort of magic?
I swear I was reading flask documentation and now you post a video. Thank you so MUCH
BTWBrad, what magic classes do you take,?
Come on, you know I can't tell you that. Nice try though :)
I was just looking into it too! Brad is in tune
me too.
Dont know why Traversy decided to create the database in the terminal makes no sense to me, instead import create_engine from sqlalchemy, then engine=create_engine(use the url Traversy uses) then db.Model.metadata.create_all(engine) and thats it ! You can add ‘if not database_exists(engine.url): db.Model.metadata etc.’ to only create database if it does not exist, that will make your program portable. There are many ways to check if a database exists but installing the sqlalchemy_utils and importing database_exists is easier
Tell me more about this please, Have you any videos concerning this?
Thank you Brad, i learn anything from node js, react js, and today currently learn python(flask) from you. I prefer with how you teach some thing
Once again a simple and perfect demonstration, love your work! Keep it up
File "C:\Users\Engr\Documents\flask-api\traversy\app.py", line 47, in add_product
name = request.json['name']
TypeError: 'NoneType' object is not subscriptable
after I try to make the same post request with postman. And I got the same error with the code from github so I wrote all the code correctly. Can anyone help with this?
@Isaac Neace SAME PROBLEM
Thank you so much for this.
As a part of an interview assignment, I was given a task to create a CRUD system and expose APIs for a table.
Starting from absolutely 0 knowledge about Flask, I was able to fully develop it thanks to you.
Thank you so much!
Do let me know if there is some way I can buy you a couple of beers (your Paypal?)
I would really appreciate a tutorial on how this could work with NoSQL! Great work, Brad.
On the get all products route I had to remove .data from result in order to see my products. I was getting the error, " 'list' object has no attribute 'data' ".
Use return jsonify(result) instead. You don't need .data
I really love Flask coz it's is similar to express when it comes to build apis but I would love to watch a video with authentication added to this via Rest. Anyways your contents are making our lives in this competitive world easier. Thanks teacher
Flask is ridiculously simple to work with Rest APIs. So grateful with this tutorial
My lunch break well spent watching another Brad tutorial!
Breaking Marshmallow changes since the version used to record this tutorial.
3.0.0b7 (2018-02-03)
Features:
Backwards-incompatible: Schemas are always strict (#377). The strict parameter is removed.
Backwards-incompatible: Schema().load and Schema().dump return data instead of a (data, errors) tuple (#598).
Thank you for providing such great content. However, I believe many of us would like to see this project expanded further. Right now, as great this tutorial might be, it's not suitable to use for any real-world application. Some things I would like to see are: breaking the app.py into multiple files to separate out the models and routes, using token authentication, implementing model relationships, etc. I hope you please consider. Thank you.
If you're getting an empty object for your JSON response, you need to add the 'many' option to the 'dump' method.
dump(arr_objs, many=True)
Just a note:
jsonify does more than the simple conversion (if I'm not mistaken), it actually does some other prep steps to make it ready to be used as a response. For a simple conversion, you can use the built in module `json` ... json_string = json.dumps(som_python_dict)
I am currently studying this same topic, great having Brad’s take on it.
If you found an error about strict or marshmallow. Install the packages following this version:
marshmallow==3.0.0b6
marshmallow-sqlalchemy==0.15.0
Thanks from Japan.
Your video is very useful to me.
Thank you very much.
I love this; that you make real projects now days that are more "complete" and not just 'frontend', but I would like to see more front-end, please. E.g. you could explain how 'content: ""' works when people use it "before" and "after" when they do these seemingly magic stuff. How does it work? Looks like magic to me, and would like to know more about it.
For anyone following this tutorial in 2021 The strict parameter was removed. Schemas are always strict.
So
product_schema = ProductSchema()
products_schema = ProductSchema(many=True)
Thanks
Ohhhh Thankssss Brad .You are the best .I am just Searching for this tutorial ......Love you man...
Outstanding, so clear and simple, thank you.
name = request.json['name']
TypeError: 'NoneType' object is not subscriptable - keep getting this error and looking all over for it, but I have no idea what it means. Can anyone help?
Awesome video. could you make a small video that integrates a flask backend and a react frontend. I would like to know how the data flows between both ends. More so how to send data from the frontend and receive it in the flask backend. Please if you do get a chance make a video on it. Thank you.
Good Tutorial Thanks Brad Might be something new with Marshmellow but I think that this is the correct synatax - # Init Schema
product_schema = ProductSchema()
products_schema = ProductSchema(many=True)
I tried it with strict and it was dropping an error .. above worked.
thanks
If you have an empty json output after post request, Change the "Fields" to "fields" in the product schema
Thats nice Brad, can yu make authentication on this API
I will see if I can do that
@@TraversyMedia that will be fine, and also how to deploy flask app on do with mysql db
@@TraversyMedia Authentication to this API, pleeeeease :)
Yes you can use Flask-Login and Flask-Jwt for auth.
@@TraversyMedia yes please! this is exactly what I want to learn!
Thank you very much for this tutorial.
product_schema = ProductSchema(strict=True) was throwing up an error for the flask server. So I omitted it and the program ran without any hiccups. I had to use the POSTMAN desktop app to request the API.
Thank a lot again.
Regards Ed
name=request.json["name"]
TypeError: 'NoneType' object is not subscriptable
update_product error
please help
Check headers content-type and set it to json
in postman
Watched this late, but the information is still relevant! A life save! Thanks Brad!
Thank you for this video. Please make a video on 'Flask as Rest API and Angular as the Front end.' Thumbs up.
Hi Brad, I've been following your channel for the past few months. I have learnt HTML and CSS as well as Python from your channel. I was forced to learn Java in my college as part our curriculum (which I find hard as a first time coder) and currently, we are going to make an Android app Although I find React Native to be really efficient, my professors, insist that I should make an app through Java. Can you include a crash course on Java and Android Studio. sorry if I'm asking too much. Your work is awesome as always
Thanks for very nice explanation. It is explained in such a way that beginner gets confidence to go ahead without any frustration.
No need for strict=True, now schemas are always strict!
Had a lot of issue with that then i just remove it completely and also in return just jsonfy(result)
I m currently working on a project with the exact same tools and man I needed a video like this on
Nice. Lots of online documentation is a bit out of date and will recommend flask-restful or flask-restplus. A better alternative is the stack you use, plus flask-classful. So easy and lightweight.
Hey Brad, you are a gift from the Web Dev Gods.
This year is going to be awesome for your students first React and now this. Thanks Sir!
This was a great video that explained some elements that I hadn't quite grasped within my existing API. Covered all CRUD scenarios however I feel "Add Multiple Products" would have just finished those scenarios off.
Nice tutorial. It is clearly the best I have seen since I began Flask API.
But, one of my biggest questions I always not answered. This question is the next one:
How would you structure a complete API in Flask?
Have you some resource which can answer to this or any public project which can be used as example?
Can someone please tell what was the purpose of the below commands running on python shell.
Does it create objects as well or just created the db.
From app import db
Db.create_all()
Hello! while passing the first product by postman this console throws me this error
TypeError: 'Product' object is not iterable
did that happen to anyone else? you can help me?
Excellent tutorial. So far I have not figured out how to place classes in a separate file. Any suggestions on that?
so why not use python venv? Also I got an error:
TypeError: __init__() got an unexpected keyword argument 'strict'
Lo corregiste, compañero??? tengo el mismo error
Remove 'strict=True', by default, they are already strict
@@alannava6132 Eliminar 'strict = True', de forma predeterminada, ya son estrictos
@@mike111615 Gracias!
Great video. This looks so simple I wish I could find a gig doing Python and Flask everyday :)
For a REST API I think it would be better to showcase the PATCH method for updating a product. There is a whole debate to be had about idempotence, but most of the time you do not want to supply the entire product in order to update a single field. Especially if the API is not consumed by a frontend, but utilized directly by an end-user to fetch and modify data.
Thanks for sharing a little of knowledge. This makes the world a better place.
I am getting error
400 Bad Request
Bad Request
Failed to decode JSON object: Expecting value: line 1 column 1 (char 0)
Is anybody receiving the "TypeError: 'NoneType' object is not subscriptable" error?
If you are trying to receive data from frontend along with API as data, use
name = request.form.get('name') ==> instead of ==> name = request.json['name']
@@arunaravindpm still not work, I mean it works but the value of each key pair will be null. I wonder why
Forget it, now it works just like in the tutorial without changing anything-_-
Thanks Brad ! Lots of Love
No problem, thanks for watching :)
At 26:40, would it be all right to replace the two statements:
result = products_schema.dump(all_products)
return jsonify(result.data)
with:
products_schema.jsonify(all_products)
? I'm too much of a noob to understand the difference 🙈
This is a great tutorial. Thanks for putting this up. Definitely saving this video.
Thank you from India 🇮🇳 Sikkim.
Very nice tutorial. Would it be possible to elaborate at some point about the necessity of Marshmallow? I didn't quite get why it is being used.
Great video as ever guys. Have a nice and successful 2019 , best wishes from México to both of you!
It's showing an error like "Instance of 'SQLAlchemy' has no 'Column' member" what should i do ?
Great Tutorial for the Flask beginners! Thanks a lot.
Pipenv is my fav package at the moment! So awesome!
Thanks for the awesome vid, really easy to follow and learned so much
great video, I have a question. If I give an example, I have a user table and a vehicle table user and my vehicle table are one-to-many linked. When I get my user table, the vehicle's id comes. How do I get all the values of the vehicle to be listed, not just the id?
Isn't it better to use a query param like product?id=[ID] rather than product/[ID] ? And how would we do it? Also, please do a video where you show us how to add authentication and a front-end.
Excellent video once again Brad!!! I would be grateful if you could do a Flask React app with deployment!
Great Video man... keep the good work. It was a really really good learning. Many thanks for putting this effort and spreading useful knowledge.
Thank you Brad, It is very good tutorial. The sample code works for me.
Great stuff. Thanks for this. As this a light-weight solution to creating a RESTful database, or could it work with heftier amounts of data?
In testing POST on Postman and in Terminal, I was receiving the following error: jsonify() missing 1 required positional argument: 'obj'
Originally, I had deleted the strict=True parameter since it produced an error in the compiler. Inadvertently, I removed the parens after ProductSchema.
product_schema = ProductSchema(strict=True)
products_schema = ProductSchema(many=True, strict=True)
So, when the program reached the
return product_schema.jsonify(new_product)
there was nothing there.
Hi Charles .. I ran into the same .. while testing POST on Postman .. I could ony get " { } " as Post ... with no values ..
Please help me .. if you solved this one .. thanks 🙌
In case you get error: File "C:\Users\Playground\FlaskAPI\app.py", line 65, in get_products
return jsonify(result.data)
AttributeError: 'list' object has no attribute 'data' just remve data then the error gone
I keep getting the error "ModuleNotFound" with flask_sqlalchemy and flask_marshmallow.
Need help!!
Press "Ctrl + Shift + P" : Show all commands
Type: "Configure Language Specific …", then pick "Python"
"settings.json" will open. Check in this json file if there is a line like this: {"python.jediEnabled": false}
If yes, then comment it out, then reload VSCode, the problem should be solved
touch app.py file creation command not working in vs code terminal??
27:23 postman give me "'list' object has no attribute 'data'" . It didn't reveal the list that in the video
I found the sollution. Just remove the 'data' and return only jsonify(result).
@@MrPoime thanks man, that worked smoothly :)
Hi Brad, I would be very happy to have a tutorial about Gatsby + Netlify CMS, I'd be interested to learn the JAM stack.
Awesome video! I have been wondering how to make a API. Thank you !
thank you so much sir , It's easy to use, and feels modern and natural.
if you guys find error: TypeError: __init__() got an unexpected keyword argument 'strict', just remove "strict=True" in app.py
Getting error in get-all method, after doing this. can you help?
Remove 'strict=True', by default, they are already strict
For "return jsonify(result.data)", I'm getting error: "AttributeError: 'dict' object has no attribute 'data' // Werkzeug Debugger".
Can you advise on how to overcome it?
it is apparently not a dict when you print result, but a list. so do "return jsonify(result)" instead :)
Really clear tutorial, thank you very much!
If you guys find error : AttributeError: 'list' object has no attribute 'data', just change the code ''jsonify(result.data)" to "jsonify(result)" in get all product
TypeError: __init__() got an unexpected keyword argument 'strict'
pls help
removing 'strict=True' got rid of this error (NOTE: I'm only at 19:36 of this video)
product_schema = ProductSchema()
products_schema = ProductSchema(many=True)
The documentation specifies that starting with Marshmallow version 3.0, schemas are always strict so the strict parameter was removed (marshmallow.readthedocs.io/en/stable/upgrading.html)
Brad, I'm a big fan of you. please do the full project-based course of a flask in udemy.
I can't get this to work. I've installed all the necessary dependencies and pulled the code from Github in my attempts to troubleshoot the problem. The interpreter keeps on complaining about the strict in the ProductSchema(strict=True).
Anyone who has an idea of what I have to do to sort this out please help 😣
Remove 'strict=True', by default, they are already strict
Is it better to use vanilla flask or flask-restful for building REST API? What are your opinions?
how would you add a script that would create the db if it doesn't exist and you are in debug more?for instance if you dockerize this and want to just run the container and have it do the things straight away. I suppose another python file in your dockerfile?
I was watching your other flask tutorial just the other day, so this video came at the perfect time. Thanks, Brad! I've even been telling my girlfriend about you.