Split Python Flask app into multiple files

Question

I'm having trouble understanding how to split a flask app into multiple files.

I'm creating a web service and I want to split the api's into different files (AccountAPI.py, UploadAPI.py, ...), just so I don't have one huge python file.

I've read that you can do this with Blueprints, but I'm not entirely sure that route is the right one for me.

Ultimately I want to run one Main python file and include other files so that when it runs, they are considered one big file.

For example if I have Main.py and AccountAPI.py I want to be able to do this:

Main.py:

from flask import Flask
import AccountAPI

app = Flask(__name__)

@app.route("/")
def hello():
    return "Hello World!"

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

AccountAPI.py:

@app.route("/account")
def accountList():
    return "list of accounts"

I know with this example it obviously won't work, but is it possible to do something like that?

Thanks

Solution 1

Yes, Blueprints are the right way to do it. What you are trying to do can be achieved like this:

Main.py

from flask import Flask
from AccountAPI import account_api

app = Flask(__name__)

app.register_blueprint(account_api)

@app.route("/")
def hello():
    return "Hello World!"

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

AccountAPI.py

from flask import Blueprint

account_api = Blueprint('account_api', __name__)

@account_api.route("/account")
def accountList():
    return "list of accounts"

If this is an option, you might consider using different URL prefixes for the different APIs/Blueprints in order to cleanly separate them. This can be done with a slight modification to the above register_blueprint call:

app.register_blueprint(account_api, url_prefix='/accounts')

For further documentation, you may also have a look at the official docs.

Solution 2

Using Blueprint you can add your routes in the routes directory.

Structure

app.py
routes
    __init__.py
    index.py
    users.py

__init__.py

from flask import Blueprint
routes = Blueprint('routes', __name__)

from .index import *
from .users import *

index.py

from flask import render_template
from . import routes

@routes.route('/')
def index():
    return render_template('index.html')

users.py

from flask import render_template
from . import routes

@routes.route('/users')
def users():
    return render_template('users.html')

app.py

from routes import *
app.register_blueprint(routes)

---

If you want to add a new route file, say accounts.py, you just need to create the file accounts.py in the routes directory, just like index.py and users.py, then import it in the routes.__init__.py file

from .accounts import *

Solution 3

If you are using blueprints and want to route / redirect to a url of your blueprint inside a template you are using you need to use the correct url_for statement.

In your case if you would like to open the url account of your blueprint you have to state it like this in your template:

href="{{ url_for('account_api.account') }}"

and for the main app it would look like this:

redirect(url_for('account_api.account'))

Otherwise the werkzeug library will throw an error.

Solution 4

One another way to do this can be with lazy loading, where you would explicitly attach view functions on need basis.

View more solutions

Comments

[user1751547]

This worked perfectly for me thanks! I guess I should have read the Blueprint docs more carefeully.

[jeyraof]

Hey, I have a question. In following above code, does url for accountList() be matched 'domain/accounts/account'?

[matchifang]

Can Main.py and AccountAPI.py have a shared global variable that is in either of the files?

[Abhishek J]

It's throwing an Import Error

[GA1]

Is there a simple solution for putting accountList inside a class in the same file?

[TomSawyer]

Importing in middle of the file can be considered as bad practice?

[Ashok Sri]

Worked like a charm, further how to add protected end point by using JWT in separate .py files

[cyroxx]

@AshokSri This goes beyond the scope of the question. I would recommend to search for a good tutorial on Flask and JWT.