In my Python Flask app I have Blueprint Routes defined that correspond to API endpoints,
# Submit Agreement (Insert or Update)
#bp.route('submitAgreement', methods=['POST'])
#auth.login_required
def submitAgreement():
#...code...
# Get Existing Agreement
#bp.route('fetchAgreement', methods=['POST'])
#auth.login_required
def fetchAgreement():
#...code...
I need to define a common route pass-through or filter that will perform authorization prior to executing the code. The authorization needs to be, if the URL contains the param id=.., check that that ID belongs to the logged-in user.
Is there a way to define a custom "aspect" or filter with this code in Python Flask?
Flask offers an
#app.before_request decorator
You can substitute app for bp to apply the function you define to just the blueprint.
I'm new to python and working on a small code for flask webserver.
I need a solution to achieve the below scenario.
I have app.py which calls settings.py for flask user ID and password and also a route.py to handble the routes.
Now I want users to be asked for authentication only for few routes and other routes should override authentication and perform operation based on specific users/specific host.
Can this be achieved?
As of now its asking for authentication for all the routes
You can write a decorator. Decorators are usually called before the definition of a function you want to use (in this case whenever you want to authenticate your route).
For example:
def requires_auth():
def wrapper(f):
#wraps(f)
def decorated(*args, **kwargs):
if 'id' not in flask.session:
return unauthorized_abort()
else:
if flask.session['first_login']:
return f(*args, **kwargs)
else:
return flask.render_template('change_password.html')
return decorated
return wrapper
After writing this decorator, we can easily use authentication for particular routes only. This below code shows #require_auth() which will easily help for particular routes only.
#app.route('/data/get_data',methods=['GET'])
#requires_auth()
def get_data():
Although the above answer solves my query, I was looking for more specific scenario.
Here's what I changed,
I commented #app.config['BASIC_AUTH_FORCE'] = True in flask settings
Here is what changed in routes.py
Added
basic_auth = BasicAuth(app)
and I added this decorator
#basic_auth.required for the routes which requires authentication.
As a security measure, I am allowing Unauthenticated requests only from a specific host using headers.
Can someone show me examples of making a RESTful API which uses database information in Flask? I have no idea how to implement POST, PUT and DELETE and I always get the 405 error where I can't use the method in url.
Have you add request method in your routing? you can following reference from: flask-restful
from flask import Flask, request
from flask_restful import Resource, Api
app = Flask(__name__)
api = Api(app)
class TodoSimple(Resource):
def get(self):
# do get something
def put(self):
# do put something
def delete(self):
# do delete something
def post(self):
# do post something
api.add_resource(TodoSimple, '/api/todo')
if __name__ == '__main__':
app.run(debug=True)
in flask-restful the HTTP actions (GET, PUT, POST, DELETE) have their corresponding method in the resource class, so is just a matter of defining those method in the resource (with the corresponding parameter defined in the routing)
I've also built a lightweight framework for building restful apis that makes it super easy to build apis. You can take a look at the code to have an idea of how an API can be built, configured and run, and of course, build on top of it
here's the code: https://github.com/sebastiandev/peach
I'm writing a proxy in Flask. The proxy should forward all requests except one small subset, for which some additional checks should be performed.
Since there is a variety of routes I found this example in the docs
to match all URLs:
from flask import Flask
app = Flask(__name__)
#app.route('/', defaults={'path': ''})
#app.route('/<path:path>')
def catch_all(path):
return 'You want path: %s' % path
if __name__ == '__main__':
app.run()
What I'm wondering is what is the best way to have one view function that handles this subset of routes, and another view function that handles all others ?
Flask has decorators to perform action before handling the request.
#app.after_request
def catch_all(response):
# * additional checks here *
You can stop the normal handling by returning data
If any of these function returns a value it’s handled as if it was the return value from the view and further request handling is stopped.
It is often use for authentication or permission checks.
The Flask documentation shows:
add_url_rule(*args, **kwargs)
Connects a URL rule. Works exactly like the route() decorator.
If a view_func is provided it will be registered with the endpoint.
endpoint – the endpoint for the registered URL rule. Flask itself assumes the name of the view function as endpoint
What exactly is meant by an "endpoint"?
How Flask Routing Works
The entire idea of Flask (and the underlying Werkzeug library) is to map URL paths to some logic that you will run (typically, the "view function"). Your basic view is defined like this:
#app.route('/greeting/<name>')
def give_greeting(name):
return 'Hello, {0}!'.format(name)
Note that the function you referred to (add_url_rule) achieves the same goal, just without using the decorator notation. Therefore, the following is the same:
# No "route" decorator here. We will add routing using a different method below.
def give_greeting(name):
return 'Hello, {0}!'.format(name)
app.add_url_rule('/greeting/<name>', 'give_greeting', give_greeting)
Let's say your website is located at 'www.example.org' and uses the above view. The user enters the following URL into their browser:
http://www.example.org/greeting/Mark
The job of Flask is to take this URL, figure out what the user wants to do, and pass it on to one of your many python functions for handling. It takes the path:
/greeting/Mark
...and matches it to the list of routes. In our case, we defined this path to go to the give_greeting function.
However, while this is the typical way that you might go about creating a view, it actually abstracts some extra info from you. Behind the scenes, Flask did not make the leap directly from URL to the view function that should handle this request. It does not simply say...
URL (http://www.example.org/greeting/Mark) should be handled by View Function (the function "give_greeting")
Actually, it there is another step, where it maps the URL to an endpoint:
URL (http://www.example.org/greeting/Mark) should be handled by Endpoint "give_greeting".
Requests to Endpoint "give_greeting" should be handled by View Function "give_greeting"
Basically, the "endpoint" is an identifier that is used in determining what logical unit of your code should handle the request. Normally, an endpoint is just the name of a view function. However, you can actually change the endpoint, as is done in the following example.
#app.route('/greeting/<name>', endpoint='say_hello')
def give_greeting(name):
return 'Hello, {0}!'.format(name)
Now, when Flask routes the request, the logic looks like this:
URL (http://www.example.org/greeting/Mark) should be handled by Endpoint "say_hello".
Endpoint "say_hello" should be handled by View Function "give_greeting"
How You Use the Endpoint
The endpoint is commonly used for the "reverse lookup". For example, in one view of your Flask application, you want to reference another view (perhaps when you are linking from one area of the site to another). Rather than hard-code the URL, you can use url_for(). Assume the following
#app.route('/')
def index():
print url_for('give_greeting', name='Mark') # This will print '/greeting/Mark'
#app.route('/greeting/<name>')
def give_greeting(name):
return 'Hello, {0}!'.format(name)
This is advantageous, as now we can change the URLs of our application without needing to change the line where we reference that resource.
Why not just always use the name of the view function?
One question that might come up is the following: "Why do we need this extra layer?" Why map a path to an endpoint, then an endpoint to a view function? Why not just skip that middle step?
The reason is because it is more powerful this way. For example, Flask Blueprints allow you to split your application into various parts. I might have all of my admin-side resources in a blueprint called "admin", and all of my user-level resources in an endpoint called "user".
Blueprints allow you to separate these into namespaces. For example...
main.py:
from flask import Flask, Blueprint
from admin import admin
from user import user
app = Flask(__name__)
app.register_blueprint(admin, url_prefix='admin')
app.register_blueprint(user, url_prefix='user')
admin.py:
admin = Blueprint('admin', __name__)
#admin.route('/greeting')
def greeting():
return 'Hello, administrative user!'
user.py:
user = Blueprint('user', __name__)
#user.route('/greeting')
def greeting():
return 'Hello, lowly normal user!'
Note that in both blueprints, the '/greeting' route is a function called "greeting". If I wanted to refer to the admin "greeting" function, I couldn't just say "greeting" because there is also a user "greeting" function. Endpoints allow for a sort of namespacing by having you specify the name of the blueprint as part of the endpoint. So, I could do the following...
print url_for('admin.greeting') # Prints '/admin/greeting'
print url_for('user.greeting') # Prints '/user/greeting'
Endpoint is the name used to reverse-lookup the url rules with url_for and it defaults to the name of the view function.
Small example:
from flask import Flask, url_for
app = Flask(__name__)
# We can use url_for('foo_view') for reverse-lookups in templates or view functions
#app.route('/foo')
def foo_view():
pass
# We now specify the custom endpoint named 'bufar'. url_for('bar_view') will fail!
#app.route('/bar', endpoint='bufar')
def bar_view():
pass
with app.test_request_context('/'):
print url_for('foo_view')
print url_for('bufar')
# url_for('bar_view') will raise werkzeug.routing.BuildError
print url_for('bar_view')
If you have same class name and want to map with multiple routes, then specify the endpoint, so that framework will differentiate between two:
class ClassName(Resource):
def get(self):
if request.endpoint!='hello':
return {"data": "Hello"}
elif:
return {"data" : "World"}
api.add_resource(ClassName, '/rout1', endpoint = "world")
api.add_resource(ClassName, '/rout2', endpoint="hello")
#app.route('/') #Endpoint
def a_function(): #View function
return 'view'
Inside Flask, every endpoint with its request methods mapped to a view function. When you use app.route decorator you are actually adding a URL rule.