I have some url paths and want to check if they point to a url rule in my Flask app. How can I check this using Flask?
from flask import Flask, json, request, Response
app = Flask('simple_app')
#app.route('/foo/<bar_id>', methods=['GET'])
def foo_bar_id(bar_id):
if request.method == 'GET':
return Response(json.dumps({'foo': bar_id}), status=200)
#app.route('/bar', methods=['GET'])
def bar():
if request.method == 'GET':
return Response(json.dumps(['bar']), status=200)
test_route_a = '/foo/1' # return foo_bar_id function
test_route_b = '/bar' # return bar function
app.url_map stores the object that maps and matches rules with endpoints. app.view_functions maps endpoints to view functions.
Call match to match a url to an endpoint and values. It will raise 404 if the route is not found, and 405 if the wrong method is specified. You'll need the method as well as the url to match.
Redirects are treated as exceptions, you'll need to catch and test these recursively to find the view function.
It's possible to add rules that don't map to views, you'll need to catch KeyError when looking up the view.
from werkzeug.routing import RequestRedirect, MethodNotAllowed, NotFound
def get_view_function(url, method='GET'):
"""Match a url and return the view and arguments
it will be called with, or None if there is no view.
"""
adapter = app.url_map.bind('localhost')
try:
match = adapter.match(url, method=method)
except RequestRedirect as e:
# recursively match redirects
return get_view_function(e.new_url, method)
except (MethodNotAllowed, NotFound):
# no match
return None
try:
# return the view function and arguments
return app.view_functions[match[0]], match[1]
except KeyError:
# no view is associated with the endpoint
return None
There are many more options that can be passed to bind to effect how matches are made, see the docs for details.
The view function can also raise 404 (or other) errors, so this only guarantees that a url will match a view, not that the view returns a 200 response.
In addition to the #davidism answer (The core developer of flask).
Note that if you want to discover the view function of the current url processed by flask app. You can use the Request object of flask which :
The request object used by default in Flask. Remembers the
matched endpoint and view arguments.
and the Flask.view_functtions which:
#: A dictionary mapping endpoint names to view functions.
#: To register a view function, use the :meth:route decorator.
def get_view_function():
if request.url_rule:
return current_app.view_functions.get(request.url_rule.endpoint, None)
Related
In Flask, you create routes like this:
from flask import Flask
app = Flask(__name__)
#app.route("/foobar")
def foo_bar_endpoint():
...
But the route decorator also has an endpoint parameter. The documentation just states:
the endpoint for the registered URL rule. Flask itself assumes the name of the view function as endpoint
Why should / would one not simply name the function as the endpoint should be called? Is this relevant for anything else than url_for?
The "endpoint" is an arbitrary name you provide, which is basically the canonical thing that a route refers to. You're not actually mapping a URL to a function there, you're mapping a URL to an endpoint and are attaching a view function to that endpoint.
URL → endpoint → function
You're just doing all that in one action, and the name of the function automatically becomes the name of the endpoint in the process. But you could do this all separately and register an endpoint for a URL, and later attach a function to that endpoint:
Basically this example:
#app.route('/')
def index():
pass
Is equivalent to the following:
def index():
pass
app.add_url_rule('/', 'index', index)
If the view_func is not provided you will need to connect the endpoint to a view function like so:
app.view_functions['index'] = index
https://flask.palletsprojects.com/en/1.1.x/api/#flask.Flask.add_url_rule
You may want to name your endpoint independently of your function, if you're under some constraint for the function name but are already referring to the endpoint from elsewhere, especially during refactoring, as one possible example where that might become relevant.
The URL is for external clients, for HTTP-requests.
The endpoint is for internal usage if you need to know which URL to redirect for example without any hardcoding.
In case you not defining endpoint your code looks like:
blueprint = Blueprint("bp_1", __name__)
#blueprint.route("/foobar")
def foo_bar_endpoint():
...
url = flask.url_for("bp_1.foo_bar_endpoint")
In case you define endpoint, you use function url_for with its name:
#blueprint.route("/foobar", endpoint="custom_name")
def foo_bar_endpoint():
...
url = flask.url_for("bp_1. custom_name")
i have a table which include all users and two columns at the end (Edit,Delete) and i just enabled the delete column, the issue is when i click on the delete icon the record will be deleted but the url will stuck on the delete function even if i used return render(request,'getUsersInfo.html') which is get all records function
Model Name: Users
urls:
from django.urls import path
from django.conf.urls import url
from . import views
urlpatterns = [
path('signup.html',views.signup,name=''),
path('getUsersInfo.html',views.getAllUsers,name=''),
url(r'^deleteUser/(?P<fullname>\D+)/$',views.deleteUser, name='deleteUser'),
# this is how to call a function without parameters url(r'^deleteUser/$',views.deleteUser, name='deleteUser'),
in the same view i have 3 functions (singup "add user", getAllUsers "get all the records to the table,deleteUser)
views:
def getAllUsers(request):
print("getAllUsers")
thesearchValue = ''
if 'SearchValue' in request.GET:
thesearchValue = request.GET['SearchValue']
print(request.GET['SearchValue'])
allUsers = User.objects.filter(fullname__icontains=thesearchValue)#all()
# return render(request,'getUsersInfo.html',{'allUsers':allUsers})
return render(request,'getUsersInfo.html',{'allUsers':allUsers})
else:
print("Empty")
allUsers = User.objects.all()
return render(request,'getUsersInfo.html',{'allUsers':allUsers})
def deleteUser(request,fullname):
print('delete the user')
todelete = User.objects.filter(fullname=fullname)
todelete.delete()
return render(request,'getUsersInfo.html')
Notice that i used return render(request,'getUsersInfo.html') which should call getAllUsers(request): but the url stuck on http://127.0.0.1:8000/deleteUser/John/
Rendering the same template as another view does not mean that you will somehow call other views. A template is nothing more than a tool to specify how to convert context data to a string, that is passed as HTTP response. You can use the same template in multiple views, and a view can render multiple templates.
You can make use of redirect(..) [Django-doc] to return a HTTP redirect response (302):
from django.shortcuts import redirect
def deleteUser(request,fullname):
print('delete the user')
todelete = User.objects.filter(fullname=fullname)
todelete.delete()
return redirect(getAllUsers)
Note: A GET request is not supposed to have side-effects, hence removing
objects when a user makes a GET request, is not compliant with the HTTP
standard. Therefore it might be better to remove a User with a POST request.
Is there a way to pass request object from one view to another? Or do I have to dissect the request into individual parts or use request.__dict__ and pass those?
Currenlty, because the request cannot be serialized, the below code:
def explorer(request):
collect_activities_init(request)
return render(request, 'explorer/explorer.html')
def collect_activities_init(request):
task = collect_activities.delay(request)
return JsonResponse({'status_url': reverse('explorer:collect_activities_status', kwargs={'task_id': task.id})})
#celery.task(bind=True)
def collect_activities(self, request):
api = StravaApi()
code = request.GET.get('code', '') # extract code from redirect URL query string
Will give:
WSGIRequest: GET
'/explorer/?state=&code=3ba4hgh5ad99ea3cf8e52d8&scope='>
is not JSON serializable
But I need to have the request data from the first function in the last one, because its code extracts some data from the request.
The problem you're having is not passing request between those functions, but rather that celery requires arguments passed to a celery task to be serialized.
The simple solution here would be to pull out the attributes you need from the request then pass those to the task.
So instead of
task = collect_activities.delay(request)
Do
code = request.GET.get('code', '')
task = collect_activities.delay(code)
Of course, you'll need to change the collect_activities task definition to accept the code as an argument, rather than a request object.
I found this: Django pass object from view to next for processing
The top answer uses sessions in order to pass the save the object and retrieve it later:
def first_view(request):
my_thing = {'foo' : 'bar'}
request.session['my_thing'] = my_thing
return render(request, 'some_template.html')
def second_view(request):
my_thing = request.session.get('my_thing', None)
return render(request, 'some_other_template.html', {'my_thing' : my_thing})
I can't seem to find any documentation on how to use twisted.web.util.Redirect to redirect to another function.
For more information see below.
I have the following code:
class Login(Resource):
isLeaf = True
def getChild(self, name, request):
if name == '':
return self
return Resource.getChild(self, name, request)
def render_GET(self, request):
saml = SamlRequest(request)
print('redirecting to sso')
return Redirect(saml.sso())
class SamlRequest(object):
self.auth = OneLogin_Saml2_Auth(self.request, custom_base_path=settings_path)
def sso(self):
return self.auth.login()
I need to redirect to page login to the login function inside OneLogin_Saml2_Auth.
When I try to redirect as-is I receive the error
raise TypeError("Unicode object not allowed as URL")
Is there a way to accomplish this?
twisted.web.util.Redirect is a kind of Resource, not something you return from a render method. It's most suitable if you have a "static" redirect that exists in your URL structure and redirects to a fixed location.
If you want to write a custom resource that redirects to a dynamic URL, use twisted.web.util.redirectTo(url, request), which you can call from your render_GET method just like you tried to do with Redirect.
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.