I am trying to make a website, where user can start a task on a button click, which will send an api request every x seconds/minutes. Api request gets a list of offers as a response and the task will check if the api request is the same as before.
If it is then then i want to show status on my page as: "No offers were found, still searching" and if the api response is different the status changes to: "I found an offer"
I wanted to make that process in the background and without need to refresh the page by user. I want the context["status"] to be automatically updated when new offer is found.
I tried to achieve this with threading but the page keep on loading as a task is working.
Every idea is appreciated.
Thanks!
Although you can use Ajax, I prefer to use websocket and, therefore, channels. Have a look to this tutorial: https://realpython.com/getting-started-with-django-channels/ or https://blog.logrocket.com/django-channels-and-websockets/. There are lots of tutorials on the web and also book like Django 3 by example (disclosed: I am not the author). Besides, channels is an official Django project and, it will be part of Django in the coming release.
create a custom result view in django, set a timer on your page and then use jQuery.load()
var l_timer = setInterval(function(){
$( "#result" ).load( "/my_periodic_view", function() {
alert( "Load was performed." );
});
},1000) //1000ms loop
you will require jquery. The better approach is to use ajax calls and rest api(or a socket depending on particular case), but both require additional setup on the server, and if your application does not need more realtime updates, going for the load approach is cheap easy and straightforward.
Related
I am retrieving temperature data from a sensor continuously. Now I want to display them in a webpage hosted by a node.js webserver. I struggle to understand how these data are beeing send to my html webpage because there are many ways doing that without making any way clear for me. I read in this context terms like REST, AJAX, POST and GET.
Can someone make it clear for me which would be the easiest choice in that case.
All those terms are connected with one another:
REST is a software architecture used for creating web-services that allows a requesting system (e.g. your browser) to access and/or manipulate data on the server.
GET and POST are two HTTP methods that define what you want to do to the data on the server (get it, change it, add something, ...).
Ajax is used on the client-side to retrieve data from RESTfull services.
In your case, you would create a GET endpoint in node.js (with e.g. express) and then connect to this endpoint via Ajax to retrieve the data and display it to your website.
I created a simple python script which takes a URL as input and once passed will do curl using multiple proxies and show the response code, now I want to create a webpage where others can use(my colleagues) as it will help them too, I want to create simple webpage which let them select set of proxy addresses, and input URL and upon submission, it will run the script on a machine(webserver) and populate the result to webpage using dynatable or datatable frameworks, but am not sure how or if it is possible as I didn't worked much in webserver thing, I want to know what tools I will need and how do I design it.
If python script can be called in terminal(as it needs to run curl) and show result on webpage based on output from script(which I will export to csv file), how can I do that? what to use xampp, wamp, lamp etc ?
You need a framework for this, something that will listen to your request coming from the front-end (webpage), there are tons out there as python framework, you can check bottle framework as a starting point.
So the flow would be something below.
1. from webpage, a request is sent to the backend
2. backend receive the request and run your logic (connecting to some server, computing logic, etc)
3. once backend process is done, backend then send the response to webpage
you can either use a REST approach or use templating functionality of the framework
You will need a request. You can do this in JavaScript with an ajax request there are frameworks to hook it up straight to your python which allow you not to code the JavaScript https://www.w3schools.com/xml/ajax_intro.asp there are many JavaScript frameworks that will make this easier/ shorter to code.
I’m writing a tiny Django website that’s going to provide users with a way to delete all their contacts on Flickr.
It’s mainly an exercise to learn about Selenium, rather than something actually useful — because the Flickr API doesn’t provide a way to delete contacts, I’m using Selenium to make an actual web browser do the actual deleting of contacts.
Because this might take a while, I’d like to present the user with a message saying that the deleting is being done, and then notify them when it’s finished.
In Django, what’s the correct way to return a web page to the user immediately, whilst performing a task on the server that continues after the page is returned?
Would my Django view function use the Python threading module to make the deleting code run in another thread whilst it returns a page to the user?
Consider using some task queues - one of the most liked by Django community solution is to use Celery with RabbitMQ.
Once I needed this, I set up another Python process, that would communicate with Django via xmlrpc - this other process would take care of the long requests, and be able to answer the status of each. The Django views would call that other process (via xmlrpc) to queue jobs, and query job status. I made a couple proper json views in django to query the xmlrpc process - and would update the html page using javascript asynchronous calls to those views (aka Ajax)
Ok i decided to post the question here because i really don't know what to do or even if its possible. You might tell me it's a repost or so but i aready read similar posts about it and it didn't helped me out.
Here is the deal. I have an admin interface with django and want to download a file from an external site on my server with a progressbar showing the percentage of the download.
I can't do anything while it's downloading. I tried to run a command with call_command within a view but it's the same.
Is it because Django server is single threaded? So, is it even possible do achieve what i want to do ?
Thanks in advance,
It's possible but takes some jumps though the metaphorical hoops. My answer isn't Django specific, you'll need to translate it to your framework.
Start a thread that does the actual download. While it downloads, it must update some data structure in the user's session (total size of the download, etc).
In the browser, start a timer which does AJAX requests to a "download status URL"
Create a handler for this URL which takes the status from the session and turns that into JSON or a piece of HTML which you send to the browser.
In the AJAX handler's success method, take the JSON/HTML and put it into the current page. Unless the download is complete (this part is more simple with JSON), restart the timer.
I ask the user to input some data, after that I redirect him to a 'result' website which takes several seconds to load.
I don't like this, because there is no user feedback telling him, that the server has not crashed and that his result is coming. So I was thinking about showing the user a 'loading' website stating 'please wait' and then automatically redirect him to the 'result' page. The user would see the "please-wait"-website the whole time the other one is loading, as Flask does not serve the site before it is finished with the calculations.
[Attempt to clarify]
One of the pages takes so long, because it waits for a file upload. The other side takes so long because its functions wait for data from a third party api.
How would I do that in Flask?
I was going to suggest Celery for this, but someone just posted this on the Flask mailing list, and this might be a more simpler solution: Hello-Redis-Tasks. If you still want to use Celery though, this is what you should check out: Custom states in celery
Flask's documentation for file uploads includes a section on implementing progress bars for file uploads. Choose one of the many client-side solutions to display the progress of the upload and then redirect once the upload is complete.
For the long-running server side process you have several options:
Pre-fetch (and cache) the data from the slow-to-respond API.
Hijack your link's action with JavaScript and make an ajax request for the data - update the DOM with a status message to let the user know that everything is still working.
Have a three step process. Page #1 has a link to the "Please wait ... " page (Page #2). Page #2 has a meta refresh tag pointing at Page #3 (<meta http-equiv="refresh" content="0; url=/path/to/page3">)