python: server is not receiving input from client flask

[Jerry Thefilmmaker]

On Monday, June 28, 2021 at 3:59:54 PM UTC-4, Chris Angelico wrote:
> On Tue, Jun 29, 2021 at 5:43 AM Jerry Thefilmmaker 
> <jerrythe... at gmail.com> wrote: 
> > 
> > Do you mind elaborating a bit more on making one function for any given request? 
> > 
> > As far as defining a bunch of functions that get called when particular requests come in I thought that's what I had going on in my codes. No? 
> > 
> > Also thank you, on making use of the print statement. Thought once I crossed over to the web side there was no more need for it. But what you said makes sense in terms of debugging, because sometimes I couldn't tell whether the client's variable was getting pass to my function which caused it not to be triggered. 
> > 
> > Thank you! 
> >
> Sure. I'll take a step back and look quickly at the way HTTP works and 
> how Flask figures out what function to call; you probably know all 
> this but it'll make the explanation easier. 
> 
> Every HTTP request has a method (GET, POST, PUT, DELETE, etc) and a 
> request URI. Some of the URI just figures out whether it goes to your 
> server or not, and the rest is which page within your server. So if 
> you're running on, say, port 5000 on the same computer the web browser 
> is on, then you can go to http://localhost:5000/any/path/here and 
> it'll be handled by your web app. Since the "http://localhost:5000" 
> part is the way to find the whole server, Flask just looks at the rest 
> of it - "/any/path/here" - to do its routing. So we have two parts - a 
> path and a method - that define which function is called. 
> 
> When you point your browser at "http://localhost:5000/", that's a GET 
> request (normal web page fetches are GET requests) with a path of "/". 
> 
> When you submit the form, that's a POST request (because the form's 
> method) with a path of "/" (because that's the form's action). I'm 
> assuming here that nothing is getting in the way of that, but that's 
> what printing stuff out can help with. 
> 
> So far, so good. I'm pretty sure none of what I just said is news to 
> you, but let's focus on those two requests: "GET /" and "POST /". 
> 
> The app.route decorator lets you associate a function with some 
> path/method combination. What you have in the code you shared is this:
> > @app.route("/", methods = ['POST', 'GET']) 
> > def play(): 
> > 
> > @app.route("/", methods = ['POST', 'GET']) 
> > def check_answer(ans, user):
> That tells Flask that the play function should be associated with 
> "POST /" and "GET /". And then it tells Flask that the check_answer 
> function should be associated with... the same two routes. 
> 
> I suspect that what you actually intend is for one of those functions 
> to just handle GET, and the other to just handle POST. But another way 
> you could fix this would be to change the URL used as the form's 
> action. It's up to you and what your plans are for the rest of this 
> app. 
> 
> (My recommendation is to start out with each function handling just 
> one route - say, "GET /" for play() and "POST /" for check_answer - 
> and only combine them (with multiple keywords in methods=[...]) once 
> you find that the two functions are duplicating a lot of code.) 
> 
> Once that's sorted out, you'll want to figure out exactly what 
> parameters your functions take. As a general rule, the function's 
> parameters will match the placeholders in the route, so if you're not 
> using placeholders, you'll probably just want them all to take no 
> parameters. Here are some examples from a project of mine: 
> 
> @app.route("/login") 
> def login(): 
> 
> @app.route("/force/<id>") 
> def force_timer(id): 
> 
> @app.route("/") 
> @app.route("/editor/<channelid>") 
> def mainpage(channelid=None): 
> 
> In the case of mainpage, it handles both "GET /" and "GET 
> /editor/12345", so the function might get a parameter and might not - 
> hence it takes a parameter with a default. For what you're doing here, 
> there are no placeholders in your routes, so all your routed functions 
> will take no args (like login in my example - it only ever handles 
> "GET /login", so it doesn't need anything else). 
> 
> Hope that helps! 
> 
> ChrisA

Thanks for taking the time to explained, Chris. Believe me, it helps. It had me thinking for a while. So, All the stuff about HTTP makes sense. I've been studying  and trying to wrap my head around the rest of your explanation and see how I can apply it to my codes.

So, if I separate my GET method which would be to get the web page from my POST method which would be assigned to returning value from my form, wouldn't I have to dedicate 2 functions for any given requests in that sense?

The only reason I have parameters in my functions is so I can pass value from 1 function to another which is just stuff that happens in the background. Is it necessary to have them in my decorators as well, or is it that these values won't get passed around if they're not integrated in the decorators?