Flask session not persisting - python

I have a web application running on a Flask backend with a JS client handling the front-end work. I'm running into problems trying to save a key-value pair to Flask's session object (flask.session) through a simple Flask API.
The session object I'm trying to modify is called account_id and the two API routes basically look like this:
GET
#access_service.route('/current_account.json', methods=['GET'])
#login_required
def show_current_account():
return jsonify(account_id=session.get('account_id'))
POST
#access_service.route('/current_account.json', methods=['POST'])
#login_required
def update_current_account():
if request.json:
session['account_id'] = request.json['account_id']
return jsonify(account_id=session.get('account_id'))
return jsonify()
In the JS frontend a call to the POST route is made as follows:
$.ajax({
url: '/current_account.json',
contentType: 'application/json',
type: 'POST',
data: JSON.stringify({ 'account_id': 10 })
});
Which does appear to work correctly, the ajax call returns with 200 OK and a correct return value. Logging from the Flask application also reveals that the session now contains the key account_id with value 10. However, looking up /current_account.json immediately after the POST request is made simply returns an account_id with value null.
What's stranger still is that using a simple in-browser REST client and making an identical POST request to current_account.json causes the session to work and persist as expected through full-page refresh, etc. Since that is the case, it leads me to believe that the problem has to do with the request itself rather than with Flask's session object, although I can't seem to figure out what exactly is causing it.

In my previous project, we experienced the same issue and it turns out that $.ajax does not carry cookies. We used manual session store to remedy the problem.

Related

get request data from Flask redirect

I have to create a small web app in Flask which contains an API and also an interface and I'm facing the following problem:
This would be how i handle a GET request:
#app.route('/member/<id>', methods=['GET'])
def member_get(id):
member = cursor.execute(f"select * from members where id={id}").fetchone()
if member is not None:
return to_json(member), 200
else:
return 'Not found', 404
And I would like to create some small forms with which I could do GET,POST,PUT,DELETE operations.
This would be how I get the data from the form:
#app.route('/dashboard', methods=['POST'])
def dashboard_post():
id = request.form['get_id']
return redirect(url_for("member_get",id=id))
My question is how can I get the data from the API method without actually redirecting to that page?
More precise, can I call somehow redirect(url_for("member_get",id=id)) and get the response data directly? (if I print the return of the redirect method it only shows the request status)
I assume one solution would be using the requests module, but is there a way to do it directly in Flask?
First of all, an API should always return a response in a format that is consistent and predictable. The code for member_get returns JSON in case of success but plain text in case of failure. This is not okay. You should return JSON always, with the appropriate HTTP status code. Here you are using 404 to express Not found, this is good.
You can use the jsonify function in Flask for that. And maybe normalize the response, so that is always has the same shape, whether the member ID is found or not.
Otherwise, parsing the response from your API will be harder because it is not consistent depending on the scenario.
Second point, if I understand it right: if you want to invoke the route '/member/' from within your API, you could simply do:
return member_get(id)
You call the function that is attached to the route, not the route itself. Of course you could actually fetch the page with the requests module but this is unnecessary, since the function is available internally.
Your question is not clear, but as I understand, (1) you think you have to get your form data from one view and send it to another view to do operations. (2) you are not familiar with flask request and flask-wtf. and maybe (3) looking for a way to do this without refreshing or redirecting the page.
You don't need to separate your GET and POST methods. instead you can integrate both in one view.
#app.route('/member/<id>', methods=['GET', 'POST])
To handling data, you can use flask request.
from flask import request
and access to data in your view like this:
id = request.form.get("idField")
but you can also use Flask-WTF to simply make and handle forms.
with Flask-WTF your view would be like this:
from app.forms import SearchForm
#app.route('/your-endpoint', methods=['GET', 'POST'])
def yourView():
form = your_form()
if form.validate_on_submit():
id=form.idField.data
return render_template('test.html', form=form)
the condition form.validate_on_submit() checks if you are submitting a from or you just opened it. if you submit a form and it's data are valid based on validators defined in your form, the code runs. else just renders the template and returns the page.
To learn how to make forms with Flask-WTF I recommend reading this article:
If you don't want to refresh the page or redirect it after submitting the form, you can use AJAx on your page.

Django req.POST always returns False

I am testing a shipstation webhook and I can't seem to get data from the POST request they are sending.
Their webhook docs say that their POST request will contain a body that looks like this:
{"resource_url":"https://ssapiX.shipstation.com/orders?storeID=123456&importBatch=1ab23c4d-12ab-1abc-a1bc-a12b12cdabcd","resource_type":"ORDER_NOTIFY"}
To debug the issue, I went into the Firefox and tried to send this:
And got the same result; req.method = 'POST' and req.POST = False
View controller for myNgrokAddress.ngrok.io/bot/shipstation:
#csrf_exempt
def vc(req):
print(req.META) //this works but it looks like meta-data for my browser and not from shipstation
print(req.POST.get('resource_url')) //prints false
print(req.POST) //prints false
return HttpResponse('')
When I go to localhost:4040 (the ngrok inspector) the POST body shows up, so something must be incorrectly configured on my django server.
I set ALLOWED_HOSTS = ['myNgrokAdress.ngrok.io', 'localhost'] in my settings.py. Is there something else I need to do?
What am I missing here?
The problem is with the req.POST method.
From the Django docs :
HttpRequest.POST:
A dictionary-like object containing all given HTTP POST parameters, providing that the request contains form data. See the QueryDict documentation below. If you need to access raw or non-form data posted in the request, access this through the HttpRequest.body attribute instead.
Since the data-type being sent is non-form data, you will need to use req.body instead.

Send user data in python requests module

I am unable to send the user details along with requests module i had to hard code the user details in the data payload to identify the user.
full_url = ''.join(['http://', get_current_site(request).domain, '/am/reply'])
data = {
'agent_type':'trigger',
'input':platform,
'userid':request.user.id ####==>> had to send userid like this
}
a = requests.get(full_url,params=data)
Is there way to send all general request data using requests.?
And moreover the requests url the destination view i have implemented
def index(request):
if not request.user.is_authenticated:
return HttpResponseRedirect(reverse('login'))
And request.user.id is none when url is reached through requests module
In general how should i validate a request when using requests module
Django uses request and response objects to pass state through the system.
When a page is requested, Django creates an HttpRequest object that contains metadata about the request. Then Django loads the appropriate view, passing the HttpRequest as the first argument to the view function. Each view is responsible for returning an HttpResponse object.
Some of the middleware included in Django’s contrib apps set attributes on the request. If you don’t see the attribute on a request, be sure the appropriate middleware class like authenticationmiddleware,sessionmiddleware.
Following piece of code will give the user.id if and only if the user is authenticated.
def myview(request):
if request.user.is_authenticated:
print request.user.id
else:
... # Do something else.
https://docs.djangoproject.com/en/1.10/ref/request-response/
If I understood your question correctly, You are getting request in one view, and then making a call to other view using requests module. It that case the request object in index view will be totally different because that request was sent from your server where application works, not from user. You can only get data in index view using request.GET.get("userid") and so on. And then if you will need user info, just fetch it again from database using userid. Passing request object to other view using requests library is not possible.

ReactJS server side rendering fo single page application

What I've already done
I have a frontend entirely built with React.JS.
All the business logic is handled by Django and exposed by Django REST Framework via an API.
I'm able to build for different mobile environnements (Android and iOS via Cordova)
The web application is accessible via my Django project (the same that exposes the api), the frontend is sill the same ReactJS code bundled via webpack.
The App has a single entry point, main.js which is a bundled version of my react.js components and dependencies, so my index.html typically looks like this :
<body>
<script type="text/javascript" src="/static/bundles/main-3997ad3476694c3c91cf.js"></script>
</body>
What I want to do
I want to provide a server-side rendering of my web application to let web crawlers correctly index my app on web (I'm not looking for server-side rendering for mobile builds)
How can I handle this considering the fact that my app is a Single Page Application ? I do not want to reinvent the wheel nor to duplicate my code. What kind of node.js server do I have to write in order to achieve this automatic server-side rendering ? Is there any way to provide the server side rendering directly in Django (via some tools reading and interpreting the final results of the page as displayed on the client-side and returning this raw html ?)
You have probably solved your problem by now, but I wanted to share my solution for this.
I have a very similar setup, and have something that seems to work pretty well so far. I basically have a django w/ DRF backend api and isomorphic React/Flux javascript app. I also run a node server next to the python backend server, which acts only as a 'template rendering' service. In essence, replacing the django render function.
So I simply replace the django View with a special IsoView which calls off via http to the node server and returns the rendered html.
from rest_framework.renderers import JSONRenderer
import requests
class IsoView(View):
def user_json(self):
if self.request.user.is_anonymous():
return {'anonymous': True}
else:
return UserSerializer(self.request.user, context={'request': self.request}).data
#classmethod
def render(cls, request, template, data):
req_data = JSONRenderer().render(data)
try:
headers = {'content-type': 'application/json'}
query_params = request.GET
resp = requests.post(_build_url(request.path), params=query_params, data=req_data, headers=headers, timeout=0.1)
reply = resp.json()
if resp.status_code == 302:
return redirect(reply.get('redirect'))
if 'error' in reply:
raise Exception("\n\nRemote traceback: {}".format(reply.get('traceback')))
except requests.exceptions.RequestException as err:
logger.warn('IsoView request exception: {}'.format(err))
reply = {}
return render(request, template, {
'react': reply.get('result'),
'data': data
})
And use it like so:
class HomePage(IsoView):
def get(self, request, *args, **kwargs):
return self.render(request, 'app.html', {
'user': json_data...
})
This also assumes a django template which uses something like this
<html>
<head>
<script>
window.data = {{ data|json }};
</script>
</head>
<body>{{ react|safe }}</body>
</html>
What this does is it renders the html returned from node in the body tag and also dumps the json data required for bootstrapping the app on the client in the window.data object.
This is a really simplified version of the system, but it should work. You should be careful with XSS attacks on the window.data bit, so make sure to escape all your json data but other than that, you should be all good.
Then the node template server looks really similar to any of the tutorials online that you can find for server-side react. Just a simple express app.
Alternatively, you don't need to mess around with django templates at all if you render the full ... in node and return that as a string.
Hope that helps.

Locating django app resources

tl:dr
How would a hosted django app correctly transform resource paths to match any hosted location (/ or /test or /testtest)?
Full Description
Let me try to explain what I am trying to do.
I am trying to write a somewhat re-usable django app which I intend to use from within multiple projects. This app is called systemstatus.
The systemstatus app provides a page under '$^' which provides a simple interface to query the system status.
This page makes an ajax query back to the systemstatus app to determine the actual system status and report it on the UI.
The systemstatus app provides a location '^service/$' which points to the ajax call handler.
This page has to somehow figure out the correct URI for the ajax handler depending on where this app is hosted (e.g. under / or /status or /blahblah).
I am wondering what an ideal way of doing this would be. I would say that this applies to other resources bundled inside the app too (stylesheets, images).
Right now I am using request.path to determine what the target path should be. This path is then passed down as a parameter to the template. But this approach will soon become too cumbersome to handle.
def system_status (request):
queryPath = request.path + "service/"
return render_to_response ('systemstatus.html', {'queryPath': queryPath})
My page template looks like this:
function do_ajax () {
$.getJSON ('{{ queryPath }}', function (data) {
$("#status").html (data.status);
});
}
Thanks!
You shouldn't hardcode your urls like that, but use reverse instead!
Django also has a built-in template tag to reverse urls. So you could do something like
function do_ajax () {
$.getJSON ('{% url path.to.my_ajax_view %}', function (data) {
$("#status").html (data.status);
});
}
directly in your template!
You can also send the ajax request directly to your current page's url and check if it is an ajax request or not:
def my_view(request):
if request.is_ajax():
# generate response for your ajax script
else:
# generate the response for normal request
# (render template of your page)

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