I love django, and I like flex. Django for it's cool debugging system (those yellow pages helps a lot to find bugs in my code), and flex for it possibilities.
Recently I come across a problem. If I create a form in flex and then communicate with the django server, I can't see any debugging info (when the exception happens in django).
Not sure, if there is a way to get the debugging info, because it is not accessible in command line (no error output), or in firebug....
Also I tried to create a quick html form, and post same data as I send from flex form, but it's a bit of pain to be honest.
Will be happy to listen how do you solve the problem
I've used firebug to debug the flex side of things. But I've been using json or XML for communication between the two. Since flash uses the browser to do the network stuff, the request should be visible in the net tab of firebug.
To debug the django side of things, you have a few options.
If you're using the django dev server, you can add print statements to find out what's going on.
You can write a unit test to see if the django side of things is doing what you expect it to, given known data.
You can use the pyDev debugger to run the django dev server and step through your code.
I use a combination of these to debug my code.
Related
I recently got a project that involves creating a front end application that would connect to a backend program. The backend program is a machine learning code that inputs some parameters and outputs a graph. This machine learning code was made in Python. The goal of the frontend program is for users over the web to input their data and parameters needed for the ML code to work and then receive back the graph to the front end for the users to save as a GIF or something similar.
I've never done anything of this level before, so I've been scouring the internet for answers. I've come to the answer that the front end will be html and some CSS and will connect to some API program which acts as the middle man between the front end and the backend programs. Is this the correct direction? Any references or YouTube videos about how to do something like this is greatly welcomed.
I've also looked into straight connecting from the frontend program to the ML code.
Thanks All!
So this is a very general question, hence it is hard to answer. I will give you a short pointer on how to achieve this, please note that there are many ways and I am trying to give you the easiest.
App requirements I assume:
The look is not important, functionality is the base
Any framework can be used
A beginner should be able to do this. - hence js frameworks will be avoided.
I've come to the answer that the front end will be html and some CSS and will connect to some API program that acts as the middle man between the front end and the backend programs.
Yes, this is somewhat correct, you most likely will sprinkle some JS into the frontend, but it is not required and everything is possible with just HMTL, CSS, and an API. In the frontend, you will need a <form> which will submit the input data as a post request to your API (a server). The API will then need to invoke the ML script/program and catch the resulting Image. Then you need to save the image on your server. Till now the frontend is still waiting for the request to finish so, your server has not returned anything!
Side note in a real project this would be bad because ML code can take a long time for execution and awaiting a request is caped and you could get a timeout error.
So your API/server receives the image and saves the image into a public folder which is exposed to the web, often called statics or public. Then you can redirect the user onto a second html page, which you can then dynamically render with a template language, e.g. Jinja2.
As backend technology, I would suggest that you use something which is not too opinionated because those usually take more weight from but are harder to learn. Therefore, look at Flask to build an API. For the frontend use https://getbootstrap.com/ so you do not need to write your own css. And as a template language use Jinja2.
to get yourself started I would recommend one of these sources:
https://www.youtube.com/watch?v=Z1RJmh_OqeA // Flask - explains Jinja2 as well
https://www.youtube.com/watch?v=qz0aGYrrlhU // html
https://www.youtube.com/watch?v=K-ccGZYRWzs // bootstrap froms
I am looking to create a very basic website that has a single feature. This feature works as follows:
1) The user inputs a URL to a website
2) My website will scrape the given website for necessary information
3) Apply whatever logic I need and return the processed information as a string
4) Allow user to download returned data in .txt format.
I am working on this project with one collaborator, and he has created the scraping and logic (steps 2 and 3) in Python. I have looked around stack overflow to see if it is possible to execute python scripts in a website, and the consensus seemed to be that I will require a server that executes python, and then make HTTP requests to my server.
Unfortunately, I'm quite a junior developer and lack a lot of understanding regarding web dev, and my attempts to "dive in" have left me with more questions than answers. We have a deadline that is approximately 3 days from now, and the only part that remains is to set up a server that can execute a specific python script upon HTTP requests.
I think that the source of my confusion is a lack of understanding regarding how exactly a server works, and was hoping that the kind folks here at stack overflow could help me in:
1) better understanding what's going on "under the hood" on the server side after an HTTP request arrives (or better yet, how does an HTTP request even arrive at all?)
2) Explain to me like I'm 5 what I'll need to do to deploy my website - namely all the in-between steps that receive little attention from the other posts here at stack overflow.
Some example questions that run through my head are below:
What type of server will I need?
How will I know if it can run Python?
How does the server know that I want to execute a certain script, while upon a user entering a my website's homepage URL, land at the home screen?
I've also read up on "middle layers" such as 'CGI' - what does this accomplish?
Is setting up a server reinventing the wheel?
enter code here
Is there already a service out there that does what I'm looking for?
I've accomplished a similar project overnight with a Python web framework called Django, simply by following their official tutorial: https://docs.djangoproject.com/en/1.7/intro/tutorial01/
Django abstracts away all the web stuff for you and there's plenty of documentation on deploying it in various environments. With such deadlines I suggest you to just follow the tutorial above and eventually adapt the example to your use case testing it on Django's built-in web server, then follow a guide on deploying Django projects in your production environment.
I have created a really cool Python program that I want all of my friends to try out. I really want to put the running code onto a website so people can try it all around the world. Is it possible to run Python code on a HTML page? If so, how?
In answer to your question: Yes, this is possible.
If you merely want to share your code with your friends, and allow them to try it out (even without them having Python installed), in browser, then there are a number of tools that you can use.
For example, with https://trinket.io/ , you can embed a snippet of python code in an HTML webpage or share it via a link.
Update:
Another alternative online python site is http://repl.it/. Repl.it has compiled the CPython interpreter into Javascript, using an LLVM -> Javascript compiler. It is opensource, so you could even self-host if you wanted. Caveat: Some of the libraries still have bugs in them.
The simple pedestrian solution is to create a WSGI wrapper. You can configure your web server to accept input through a form (typically) and feed that to your Python program as input, then display the program's output as the response to the form submission. Thus your program runs on the server -- which needs to have the required services and resources -- but the user interaction happens simply using the client's web browser.
There are more-complex interaction models but this is how the entire web 1.0 was set up and is quick and easy to get going. (The spec back then was the similar platform-independent CGI API.)
I am new to Python (somehow I started looking at python 2 days ago).
I tried to write a simple interactive webpage with CGI, and I used HTML form to get user input. However, as everyone knows, if I refresh the webpage, the form data will be resubmitted again. I just have no idea how to prevent this from happening.
The same problem, but in php/javascript, has been discussed and solutions can be found, but I would like to find the answer to the python case.
I hope there is someone here who can address my problem. Since I am not quite familiar with the language, I hope that, instead of solely giving me a descriptive solution, the kind one can also give me the pieces of codes necessary.
Thank you very much
Your question is not Python-specific, it's about the general web application design patterns.
Use GETs for requests that do not change the web app's state (viewing, queries and so on). Render the page in the response.
Use POST for whatever request that modifies the state (post submitting, editing, deleting).
Never render anything in the response, provide a 303 See Other redirection to the page where the results of the POST can be seen. E.g., if the user added a comment on the page http://example.com/blog/123, the POST handler can be http://example.com/submitcomment, but it should return nothing but a redirection to http://example.com/blog/123#comment5.
That's what #mikep referred to as Post-Redirect-Get.
On the related note: do yourself a favor, skip CGI. There is a number of nice and clean web frameworks for Python. Try Flask or Bottle (smaller frameworks) or go straight to Django if you are building a big app. Search here on Stack Overflow for pros and cons of different frameworks.
Just skip CGI. It's hard to build a good and maintainable CGI app, there are too many things to take care of, things that are already thought if in the frameworks.
I've been wasting time supporting a CGI application for some time, and switching to a framework was a relief.
You might want to view these lectures: http://www.udacity.com/overview/Course/cs253/CourseRev/apr2012
Week 2 will address your queries.
Take a look at POST-REDIRECT-GET web programming patern.
I'm looking for a bit of web development advice. I'm fairly new to the area but I'm sure there are some gurus out there willing to part with some wisdom.
Objective: I'm interested in controlling a Python application on my computer from my personal web hosted site. I know, this question has been asked several times before but in each case the requirements were a bit different from my own. To reduce the length of this post I'll summarize my objective in a few bullet points:
Personal site is hosted by a web hosting company
Site uses HTML, PHP, MySQL, Python and JavaScript, the majority of everything is coded by me from the ground up
An application that is coded in Python will run on a PC within my home and will communicate with an Arduino board
The app will receive commands from the internet to control actuation via the Arduino, and will transmit sensor data back to the site (such as temperature)
Looking for the communication to be bi-directional, fast and secure
Securing the connection between site and Python app would be most ideal
I'm not looking to connect to the Python application directly, the web server must serve as the 'middle man'
So far I've considered HTTP Post and HTML forms, using sockets (Python app would run as a web server), an IRC bot and reading/writing to a text file stored on the web server.
I was also hoping to have a way to communicate with the Python app without needing to refresh the webpage, perhaps using AJAX or JavaScipt? Maybe with Flash?
Is there something I'm not considering? I feel like I'm missing something. Thanks in advance for the advice!
Just thinking out loud for how I would start out with this. First, regarding the website itself, you can just use what's easiest to you, or to the environment you're in. For example, a basic PHP page will do just fine, but if you can get a site running in Python as well, I'd prefer using the same language all over.
That said, I'm not sure why you would need to use a hosted website? Given that you're already forced to have a externally accessible PC at home for the communication, why not run a webserver on that directly (Apache, Nginx, or even something like CherryPy should do)? That webserver can then communicate with the python process that is running to control your Arduino (by using e.g. Python's xmlrpclib). If you would run things via the hosting company, you would still need some process that can handle external requests securely... something a webserver is quite good at. Just running it yourself gives you all the freedom you want, and simplifies things by lessening the number of components in your solution.
The updates on your site I'd keep quite basic: commands you want to run can be handled in the request handlers of the webserver by just calling the relevant (xmlrpclib) calls. Dynamically updating the page is best done by some AJAX calls I reckon. Based on your story, these updates are easily put in a JSON object, suitable for periodically updating only the relevant segments of your page.