Learn Flask - Clean Architecture

In our last experiment, we have seen that it's fairly easy to create a single page app with Flask. But, in any other project, we will have different pages and url to use.

Here is the architecture I love.

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Let's go !

Let's make sure flask is there (type this in terminal):

pip3 install flask

(type this in terminal)

For this first episode, our code will mainly be in a package.

Let's create our package flask_app:

mkdir flask_app

Then let's create one python file in the same directory as flask_app:

touch worker.py

We are not gonna write code into those right now.

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Now I will put the path to the file we are talking about just before the codeblock balise

exemple:

/flask_app/__init__.py

int_instance = 1 # don't put that in your code

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Then, we will need to import flask and create a instance of the Flask class

/flask_app/__init__.py

from flask import Flask

app = Flask(__name__)

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Create a new file in flask_app:

touch flask_app/views.py

In flask_app/views.py import the app instance from __init__.py, with flask, we don't have to worry about circular import on this particular case. So:

flask_app/views.py

from flask_app import app

# let's add some route

#basic endpoint
@app.route('/')
def index():
    return 'hello world!'

# in case of 404 http error, send the error
@app.errorhandler(404)
def error_handler_404(error):
    return str(error)

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Then we have to import our views back into __init__.py

/flask_app/__init__.py

from flask import Flask

app = Flask(__name__)

from flask_app import views

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Now let's head back to worker.py previously created.

# import Flask instance
from flask_app import app 


if __name__ == "__main__":
    app.run()

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Run flask_app.py with this

export FLASK_ENV=development
export FLASK_APP=flask_app
flask run

Then visit http://127.0.0.1:5000/ on your browser !

Don't forget, you can find this code here !

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You made it to the end, bravo! If you have any questions, don't forget to ask. See you next time! If you spot a grammar or vocabulary mistake, please let me know in the comments.

You will be able to find a good part of the articles in this account in this repository.

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