Develop Reference

Flask API Calling a Method from Itself

My question is, can an endpoint in a Flask API call a method from another endpoint, that is a member of itself? Is there a proper way of doing this?

Yes, you can indeed call another endpoint by using redirect with url_for
If this is something you are trying to achieve.
from flask import Flask, redirect, url_for
app = Flask(__name__)
#app.route('/')
def hello_world():
return "Hello world"
#app.route('/home')
def hello_again():
return redirect(url_for('.hello_world'))
if __name__=="__main__":
app.run(debug=True)
The request to /home will redirect you to /.

Flask app doen't register jwt.user_lookup_loader, Flask-JWT-Extended

I have a Flask app with blueprints. It worked just fine, but than I decided to use flask_jwt_extended to handle tokens. It is said in docs that I can decorate method with jwt.user_lookup_loader to have current_user working. But for some reason calling current_user ends up with an error:
You must provide a `#jwt.user_lookup_loader` callback to use this method
But it is there, in the same blueprint. There is also a method, decorated with #jwt.user_identity_loader and it works perfectly well.
Here is a simplified version of my code:
from . import rpc, jwt
from flask_jwt_extended import current_user, jwt_required
bp = Blueprint('login_bp', __name__)
#jwt.user_identity_loader
def _user_identity_lookup(user):
return user.id
#jwt.user_lookup_loader
def _user_lookup_callback(_jwt_header, jwt_data):
identity = jwt_data["sub"]
user = rpc.cache_service.get_user(identity)
if user is None:
return None
return UserSchema().load(user)
#jwt_required()
#bp.route("/logout", methods=['POST'])
def logout():
rpc.cache_service.forget_user(current_user.id)
return {"status": "OK"}
jwt here is JWTManager, initialized with my app:
jwt = JWTManager()
def create_app():
app = Flask(__name__, instance_relative_config=False)
app.config.from_mapping(JWT_SECRET_KEY=os.environ["JWT_SECRET_KEY"])
...
jwt.init_app(app)
...
with app.app_context():
from . import login_bp
app.register_blueprint(login_bp.bp)
This code is basicly from the documentation examples:
https://flask-jwt-extended.readthedocs.io/en/stable/automatic_user_loading/
and I can't see what the problem might be (
Link to the repo:
https://github.com/GreenBlackSky/COIN/blob/master/api_app/app/login_bp.py

Your decorators are in the wrong order. #bp.route() needs to come before #jwt_required(), otherwise it tries to evaluate the logout method when a request comes in before it decodes the JWT in the request.

How to apply decorator to all blueprint urls in flask

I have a blueprint and some url functions,
admin_bp = Blueprint('admin', __name__)
#admin_bp.route('/dashboard', methods=['GET', ])
#flask_login.login_required
def dashboard():
context = {}
page = 'admin/dashboard.html'
return render_template(page, **context)
#admin_bp.route('/deny', methods=['GET', ])
#flask_login.login_required
def deny():
return 'hey bro you dont belong here'
I don't want to copy paste #flask_login.login_required decorator for all url functions under this blueprint. Is there a better way that I can apply decorator for all blueprint urls?

You can add before_request() as a function that will run before each request in a view.
You will then want to add decorators to inject additional functionality to the before_request function. You will want to import the login_required decorator to ensure each endpoint requires a logged in user. This decorator is part of the flask_login library.
Since it looks like your views are part of an admin, I'd also recommend adding a custom decorator to your before_request function with something like #role_required('admin'). The functionality for that decorator will live somewhere else and be imported.
#admin_bp.before_request
#login_required
def before_request():
""" Protect all of the admin endpoints. """
pass

Subclass Blueprint and override the route method.
import flask
class MyBlueprint(flask.Blueprint):
def route(self, rule, **options):
def decorator(f):
# these lines are copied from flask.Blueprint.route
endpoint = options.pop("endpoint", f.__name__)
self.add_url_rule(rule, endpoint, f, **options)
# At this point flask.Blueprint.route simply returns f.
# But you can nest a decorator.
def inner(*args, **kwargs):
# stuff you want to do before each request goes here
try:
result = f(*args, **kwargs)
# stuff you want to do on successful responses (probing status, headers, etc.) goes here
except Exception as e:
# stuff you want to do on error responses goes here
raise
return inner
Now use the new subclass in your blueprints:
-v1_blueprint = Blueprint('v1', __name__)
+v1_blueprint = MyBlueprint('v1', __name__)
No changes needed to individual routes.
The drawback of this approach is that it copies code from inside Flask. If the implementation of flask.Blueprint.route were to change in a future version, you'd need to sync MyBlueprint with it when you upgrade Flask.

How about checking the user first:
from flask.ext.login import current_user
#admin_bp.before_request
def check_user():
if not current_user.is_authenticated():
abort(401)
# your other functions without `#flask_login.login_required`

how do I make get request directly to a flask app object

I inherited a project that uses flask. This flask application has several APIs, each API has a GET function that returns a json object.
I was asked to implement an additional API that requests information from the other APIs. So my question is how do I make a GET request directly to a flask application? Is it something like....
from flask import request
#app.route('/root_dir/api_number_1/info', methods=['GET'])
def request_info_from_api_number_1():
return request.get_json()
#app.route('/root_dir/api_number_2/info', methods=['GET'])
def request_info_from_api_number_2():
return request.get_json()
When I do this the functions return None. I suppose I could always make an http request to the flask url and specify the address as localhost but it seems strange to have to make an http request when I can directly access the flask app object.

Could you just use the existing api functions?
from flask import Flask
app = Flask(__name__)
#app.route("/foo")
def foo():
return "foo"
#app.route("/foobar")
def foobar():
return foo() + "bar"
if __name__ == "__main__":
app.run(debug=True)

Flask Pluggable Views Error: "Not Implemented Error"

I am learning how to use Pluggable Views in Flask, since it seems that everyone uses them always for their advantages. I have the following file which returns an "Not Implemented Error". I am assuming that is because I am not implementing the dispatch_request. However, according to Flask's documentation, when using MethodView: "...if you implement a method called get() it means you will response to ’GET’ requests and the dispatch_request() implementation will automatically forward your request to that." Meaning, I do not require dispatch_request.
from flask import Flask, render_template, request, redirect, url_for, flash
from flask.views import View, MethodView
import os
SECRET_KEY = 'some_secret_key'
DEBUG = TRUE
app = Flask(__name__)
app.config.from_object(__name__)
class Main(View):
def dispatch_request(self):
return "Hello World!"
class Template(View):
def get(self):
return render_template('index.html')
def post(self):
result = eval(request.form['expression'])
flash(result)
return self.get()
app.add_url_rule('/', view_func=Main.as_view('main'))
app.add_url_rule('/template', view_func=Template.as_view('template'), methods=['GET', 'POST'])
if __name__ == "__main__":
app.run()

Oops.. silly Python beginner's mistake by me.
I was subclassing flask.views.View instead of flask.views.MethodView. flask.views.View requires dispatch_request, and does not automatically forward HTTP requests to dispatch_request as MethdoView does, hence the error.