Add prefix to all URLs while using Blueprint

I am trying to prefix all endpoints with /api/, but I am getting 404 in return if not providing directly in the URL or while registering blueprint.

main.py

from init import app

from modules.User import User

app.register_blueprint(User)

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

init.py

from flask import Flask

# initiating application instance
app = Flask(__name__)

# app configurations
app.config["SCRIPT_NAME"] = "/api/"

# -- OR --

app.config["APPLICATION_ROOT"] = "/api/"
...

modules/User.py

from flask import request, Blueprint

User = Blueprint("user_blueprint", __name__)

# if "/api/" is provided directly 
@User.route("/api/", methods=["GET"]) 
def get():
    return "Called get method"


# 404 if "/" is provided
@User.route("/", methods=["GET"]) 
def get():
    return "Called get method"

Solution

APPLICATION_ROOT and SCRIPT_NAME define the base path where the application is mounted by the WSGI server.

They don’t automatically add /api to your routes during development, so your @User.route("/") ends up at /, not /api/, hence you get the 404.

You can achieve the desired behavior in one of the following ways:

use url_prefix on the blueprint

Use:

# modules/User.py
User = Blueprint("user_blueprint", __name__, url_prefix="/api")

Instead of:

# modules/User.py
User = Blueprint("user_blueprint", __name__)

Code:

# main.py
from init import app
from modules.User import User

app.register_blueprint(User)


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

# init.py
from flask import Flask

# initiating application instance
app = Flask(__name__)

# modules/User.py
from flask import request, Blueprint

User = Blueprint("user_blueprint", __name__, url_prefix="/api")

@User.route("/", methods=["GET"])
def get():
    return "Called get method"

@User.route("/data", methods=["GET"])
def data():
    return "Called data method"

python main.py

>> curl http://127.0.0.1:5000/api/
Called get method
>> curl http://127.0.0.1:5000/api/data
Called data method

or use url_prefix when registering it

Use:

# main.py
app.register_blueprint(User, url_prefix="/api")

Instead of:

# main.py
app.register_blueprint(User)

Code:

# main.py
from init import app
from modules.User import User

app.register_blueprint(User, url_prefix="/api")


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

# init.py
from flask import Flask

# initiating application instance
app = Flask(__name__)

# modules/User.py
from flask import Blueprint

User = Blueprint("user_blueprint", __name__)

@User.route("/", methods=["GET"])
def get():
    return "Called get method"

@User.route("/data", methods=["GET"])
def data():
    return "Called data method"

python main.py

>> curl http://127.0.0.1:5000/api/
Called get method
>> curl http://127.0.0.1:5000/api/data
Called data method