Just yesterday got that I can't use one function that would return one template depending on cookies, and wich would be called by different methods of different routes. The reason is all the response.set_cookie() are not applied to main Bottle object HTTPResponse before the method finishes serving current route. So the question is there a way to explicitly cast application of all the changes to HTTPResponse object, so i could avoid passing complex structures to subroutines and etc.
Thank you for help!
UPD: there is a response.set_cookie('temp', 'sampletext') line for example. And then i am calling subroutine and it calls another one and so on. So In each of them i won't have request.get_cookie('temp') returning 'sampletext'. Because changes to cookies wasn't applied yet. There are in the Bottle.py code you can find following code:
class HTTPResponse(Response, BottleException):
def __init__(self, body='', status=None, headers=None, **more_headers):
super(HTTPResponse, self).__init__(body, status, headers, **more_headers)
def apply(self, response):
response._status_code = self._status_code
response._status_line = self._status_line
response._headers = self._headers
response._cookies = self._cookies
response.body = self.body
that seems to be executing once per request and changes from httpresponse objects are appliied to the response object only on finish of the rout's serving method termination.
I am asking if there is a way to apply changes to response object manually, during the route's serving method evaluation.
I am asking if there is a way to apply changes to response object manually, during the route's serving method evaluation.
No.
I'm not completely sure, but it sounds like you just want to store some state during a request.
The mechanism for this is to simply set attributes on the request object. E.g.
#route(...)
def index_page():
...
request.mydata = 'hello'
...
This is completely independent of cookies. If you need both, just set both; one on the request object and the other on the response.
Related
I'm new to flask and currently converting an existing WSGI application to run through flask as long term it'll make life easier.
All requests are POST to specific routes however the current application inspects the post data prior to executing the route to see if the request needs to be run at all or not (i.e. if an identifier supplied in the post data already exists in our database or not).
If it does exist a 200 code and json is returned "early" and no other action is taken; if not the application continues to route as normal.
I think I can replicate the activity at the right point by calling before_request() but I'm not sure if returning a flask Response object from before_request() would terminate the request adequately at that point? Or if there's a better way of doing this?
NB: I must return this as a 200 - other examples I've seen result in a redirect or 4xx error handling (as a close parallel to this activity is authentication) so ultimately I'm doing this at the end of before_request():
if check_request_in_progress(post_data) is True:
response = jsonify({'request_status': 'already_running'})
response.status_code = 200
return response
else:
add_to_requests_in_progress(post_data)
Should this work (return and prevent further routing)?
If not how can I prevent further routing after calling before_request()?
Is there a better way?
Based on what they have said in the documents, it should do what you want it to do.
The function will be called without any arguments. If the function returns a non-None value, it’s handled as if it was the return value from the view and further request handling is stopped.
(source)
#app.route("/<name>")
def index(name):
return f"hello {name}"
#app.before_request
def thing():
if "john" in request.path:
return "before ran"
with the above code, if there is a "john" in the url_path, we will see the before ran in the output, not the actual intended view. you will see hello X for other string.
so yes, using before_request and returning something, anything other than None will stop flask from serving your actual view. you can redirect the user or send them a proper response.
I'm new with CherryPy web-framework. I would like to know how can
I read POST data that was delivered via HTTP request's body .
Thanks,
Gabriel.
You can either read the body of the request with cherrypy.request.body, cherrypy.request.params or if you use the default handler then, the distinction between GET and POST values is abstracted by cherrypy and you can get the values directly from the arguments:
#cherrypy.expose
def index(self, name, age):
return "My name is %s and age is %s" % (name, age)
Your POST request must have to provide the values for name and age on the traditional forms submission.
If you are planning on using json, then use the cherrypy.tools.json_in decorator and read the cherrypy.request.json property. http://docs.cherrypy.org/en/latest/basics.html#dealing-with-json
If you are using the MethodDispatcher, then there is another way to do it: http://docs.cherrypy.org/en/latest/tutorials.html#tutorial-7-give-us-a-rest
Maybe these posts might help you:
http://blog.joel.mx/posts/cherrypy-101
http://blog.joel.mx/posts/cherrypy-101-method-dispatcher
Cherrypy handles both get and post in a similar way by passing them into the function or method that is handling the request. A good example is located at tut03_get_and_post.py in the tutorial folder within the cherrypy package.
Here is a small portion that specifically speaks to your question...
#cherrypy.expose
def greetUser(self, name=None):
# CherryPy passes all GET and POST variables as method parameters.
# It doesn't make a difference where the variables come from, how
# large their contents are, and so on.
I wonder how to access req object if there's no 'req' parameter in callback.
This is the scenario：
In ExpressJs, I have a common function, it uses to handle something with 'req' object, but not pass req into it.
module.exports = {
get: function(){
var req = global.currentRequest;
//do something...
}
}
My current solution is that I write a middleware for all request, I put the 'req' in global variable, then I can access the 'req' everywhere with 'global.currentRequest'.
// in app.js
app.use(function (req, res, next) {
global.currentRequest= req;
next();
});
But I don't know if it's good? Can anyone have suggestions?
Thanks a lot!
The only proper way is to pass the req object through as an argument to all functions that need it.
Stashing it in a global simply will not work because multiple requests can be in process at the same time if any requests use async calls as part of their processing and those multiple requests will stomp on each other making a hard to track down bug. There are no shortcuts here. Pass the current request as an argument to any code that needs it.
You cannot put request-specific data into a global in node.js, ever. Doing so will create an opportunity for two requests that are in-flight at the same time to stomp on each other and for data to get confused between requests. Remember, this is a server that is potentially handling requests for many clients. You cannot use synchronous, one-at-a-time thinking for a server. A node.js server may potentially have many requests all in flight at the same time and thus plain globals cannot be used for request-specific data.
There is no shortcut here. You will just have to pass the req object through to the function that needs it. If that means you have to change the function signature of several intervening functions, then so-be-it. That's what you have to do. That is the only correct way to solve this type of problem.
There are some circumstances where you may be able to use a closure to "capture" the desired req object and then use it in inner functions without passing it to those inner functions, but it does not sound like that is your function structure. We'd have to see a lot more of your real/actual code to be able to know whether that's a possibility or not.
Actually, this is possible with something like global-request-context
This is using zone.js which let you persist variables across async tasks.
I know for a PreparedRequest, we specifiy the timeout in session.send call, where session can be an instance of requests.Session class, as I've already seen here: http://docs.python-requests.org/en/latest/user/advanced/
But I need to put the timeout before I do the send. Somewhat inherently, to the PreparedRequest object. Because I'm using the session.send method as map function, to map to PreparedRequest instances.
def async_req2resp(reqs, session):
responses = []
try:
with futures.ThreadPoolExecutor(max_workers=workers) as executor:
for response in executor.map(session.send, requests):
responses.append(response)
except Exception as e:
print('async_requests2responses exception: ' + str(e))
return responses
Now I need to specify the timeout somehow. How can I do it?
The above code is wrapped inside a method. I am getting the session object as an argument. Is there a way I can set the timeout for all the requests that will be sent with the session object, before the parallel execution of session.send happens?
Thank you.
I'm waiting for your answer about sendit but until then, let me give you some information that should help you get the rest of the way there.
If you have a PreparedRequest object as request then you can do session.send(request, timeout=timeout_val) where timeout_val is whatever the value of the timeout is that you want.
With that in mind, this question becomes, "How do I pass that to sendit with each request?" and that question I don't have the answer for.
Side note:
You've tagged this with concurrent.futures which makes me suspect you're trying to optimize your application that uses this method. With that in mind, you should avoid appending to a list at all costs. You should, instead, try to do the following:
responses = []
try:
responses = list(sendit.map(session.send, requests))
# etc.
If you figure out how to pass the timeout parameter to sendit, feel free to suggest an edit to this answer to update it to be complete.
With the updated information in the question, I can more accurately answer your question.
Before you call executor.map you should do the following:
import functools
timedout_send = functools.partial(session.send, timeout=my_timeout)
try:
list(executor.map(timedout_send, requests))
# ...
In express you call var app = module.exports = express.createServer(); which creates a new HTTPServer object. I'd like to get access to the current req object from this app(HTTPServer) object. Is there a way to do this?
The req object is only created when the underlying HTTPServer actually gets a request, and only lasts for as long as the request is processed. So it's not really meaningful to talk about it outside the context of a callback.
During a callback, you can simply copy the appropriate data from the session object somewhere else and use that copy in your websockets code. But you can't count on the request object, or even the session object, remaining after you've finished processing the request.
Showing a small code example would be helpful; it sounds like you've got an "XY problem" (you want to accomplish a goal X and you've decided that technique Y is the right way to do it, when in fact technique Z might work better).