Develop Reference

Django taking image from Python program

I have previously written some python code which takes some information, and presents it into a chart. An example is in the link below.
The python program creates the chart, then places the numbers in the chart in the relevent location. There is some randomness as to where they are placed in the smaller squares.
My question is I would like to implement this in Django. Being new to Django, my thought process is I should be calling the Python code, which would create the image from data from the Django database, and then displaying it. I have worked out how to call the code, however there is little information about how to do so on the click of a button. This has made me question if calling the Python code is the correct way to do this?

In Django you need a view connected to a url. A template for that url shows the picture. In your view you should create picture from database data (or even better if you want to make it djangonic :-) - create a model method for that) and pass that picture's path to template with the context dictionary.

Interfacing a QR code recognition to a django database

I'm coming to you with the following issue:
I have a bunch of physical boxes onto which I still stick QR codes generated using a python module named qrcode. In a nutshell, what I would like to do is everytime someone wants to take the object contained in a box, he scans the qr code with his phone, then takes it and put it back when he is done, not forgetting to scan the QR code again.
Pretty simple, isn't it?
I already have a django table containing all my objects.
Now my question is related to the design. I suspect the easiest way to achieve that is to have a POST request link in the QR code which will create a new entry in a table with the name of the object that has been picked or put back, the time (I would like to store this information).
If that's the correct way to do, how would you approach it? I'm not too sure I see how to make a POST request with a QR code. Would you have any idea?
Thanks.
PS: Another alternative I can think of would be to a link in the QR code to a form with a dummy button the user would click on. Once clicked the button would update the database. But I would fine a solution without any button more convenient...

The question boils down to a few choices: (a) what data do you want to encode into the QR code; (b) what app will you use to scan the QR code; and (c) how do you want the app to use / respond to the encoded data.
If you want your users to use off-the-shelf QR code readers (like free smartphone apps), then encoding a full URL to the appropriate API on your backend makes sense. Whether this should be a GET or POST depends on the QR code reader. I'd expect most to use GET, but you should verify that for your choice of app. That should be functionally fine, if you don't have any concerns about who should be able to scan the code.
If you want more control, e.g. you'd like to keep track of who scanned the code or other info not available to the server side just from a static URL request, you need a different approach. Something like, store the item ID (not URL) in the QR code; create your own simple QR code scanner app (many good examples exist) and add a little extra logic to that client, like requiring the user to log in with an ID + password, and build the URL dynamically from the item ID and the user ID. Many security variations possible (like JWT token) -- how you do that won't be dictated by the contents of the QR code. You could do a lot of other things in that QR code scanner / client, like add GPS location, ask the user to indicate why or where they're taking the item, etc.
So you can choose between a simple way with no controls, and a more complex way that would allow you to layer in whatever other controls and extra data you need.

If security is not a big concern: an API with a simple get method that takes as argument the object id and I will presume you have the code to make sure if the object is given as taken it will be switched to returned.
And why not post? POST needs headers that you can't include in qr unless you have a dedicated app, so GET and the ability to use example.com/api/leaseandret?id=12345 is a better alternative that allows for better usage with a QR.
A summary of the methods*
* A note here is that GET is not forbidden from being used to modify data and send data to a server GET is exclusively for getting data from a REST purist standpoint.

sart function from template

I know that functions can't (shouldn't) be called directly from the template in Django.
But I can't find out how to properly call a simple function. Here is what I would like to do:
On my template I would like to have a hyperlink to paste all relevant information from the template to the clipboard using pyperclip. We frequently have to copy addresses from the database to paste into a word document or an email.
So, copy the data to a String variable and pass that variable to pyperclip.copy() using a hyperlink.
Seems easy enough but I can't find it out.

If you want to include Python code, use a custom template tag in Django.
It sounds like you want something a bit more complex, though. You won't be able to call pyperclip code on the client side -- there's just no Python execution environment in place.
Instead, look into using Javascript or Flash to copy data to the clipboard.

PDF Form Field Manipulation

I'm making a web interface to autofill pdf forms with user data from a database. The admin needs to be able to upload a pdf (right now targeted at IRS pdf forms) and then associate the fields in the pdf with data fields in the database.
I need a way to help the admin associate the field names (stuff like "topmostSubform[0].Page2[0].p2-t66[0]") with the the data fields in the database. I'm looking for a way to modify the PDF programatically to in some way provide this information.
Basically I'm open to suggestions on how I might make the field names appear in an obvious manner on a modified version of the original pdf. The closest I've gotten is being able to insert Tooltips into the fields in the pdf by just editting the raw pdf line by line. However when editting the pdf in this manner the field names are gibberish, and so I can't just use them.
An optimal solution would be anything that could automatically parse a pdf and set each field's tooltip to be the fields name. Anything that can be run from the command line, or any python tool, or just a basic how to correctly parse a field's name from a raw pdf file would be amazing.

There may be an easier solution than this, but you could definitely get the job done with http://www.reportlab.com/software/opensource/rl-toolkit/'>ReportLab.
If you can save the current tax forms as an image, you could determine where each of the items need to be written and develop your code so that it automatically layers the appropriate values from the database on top of the image (the tax form, or whatever it might be).
Once you've determined 1) What fields need to be pulled from the database, and 2) where they 're supposed to go on within the form...
this is essentially what you'd be doing:
from reportlab.pdfgen import canvas
report_string_values = ['Alex',500,500],['Guido',400,400],
c = canvas.Canvas('hello.pdf')
c.drawImage(background_image,x_pos,y_pos) # x_pos and w_pos are # pixels from bl origin
for rsv in report_string_values:
c.drawString(rsv.x_pos,rsv.,rsv.text)
c.showPage()
c.save()

A postscript parser lives here: https://github.com/haxwithaxe/py-ps-parser
I've been interested in playing with it, but haven't yet.

This may be way off your intended track; but, it might be worth a think. I've been working on parsing scanned structured documents into Django model instances. Using tesseract and unpaper to do the pre-processing and OCR, I get over 99% accuracy. That lets me parse the OCR output text with the Levenshtein and re modules and do a simple new_instance = MyModel(parsed1, parsed2, ...).
It seems that you are trying to do something similar. Looking at the forms at http://www.irs.gov/formspubs/ They tend to have text labels left-adjacent to the fields. Using something like py-tesseract, you should be able to OCR the labels, overlay the OCR text over the form image and allow the user to select/edit the field labels.
There is a nice little tool, ocrfeeder https://live.gnome.org/OCRFeeder, that is written in python and should give you a basic idea of how the process works in a desktop app. Good luck.

Government Forms are usually not a standard PDF but a JavaScript driven XFA in a PDF wrapper, thus to enter the data programmatically you need a lookup table as the order is rarely the visual order.
Here the first field "single yes or no" "topmostSubform[0].Page1[0].c1_01[0]" is a checkbox designated well down the list of entries. of course none in this Form are "topmostSubform[0].Page2[0].p2-t66[0]" so you need totally different look-up table for each XFA. Otherwise follow the entries (luckilly there is some sence of sequencing in this form) so free format field "topmostSubform[0].Page1[0].f1_01[0]" is near "dependent:" etc.
There are XFA dedicated applications that can extract the positions of static fields, but if the fields are dynamically adapting then the page position would be a moving feast.
For XFA you need an intelligent dedicated Adobe listing (often xml / xlsx input output supplied on request from the relevant department), or build your own if Acrobat Pro does not block the attempt.

I may be interpreting the question wrong but I have a lot of experience in pdf generation with python/django because of the site that I worked on for 5 months. I would suggest using texlive. Basically what I did was built a generic tex template for a document and then used django templating to insert the fields. I rendered the template as if it were html using render_to_string and then generated it using the pdflatex command. I ran pdflatex using pythons subprocess module and a little extra. To do the generating I used this guys pdflatex module http://bit.ly/KaDMBp , with some modifications. All the things you need are in the core.py inside of the pdflatex directory.
Ex tex document (test.tex) )
\begin{document}
my name is {{input_name}} and i live in {{input_location}}.
\end{document}
Ex rendering template with django templating and render_to_string )
params={input_name:"andrew",input_location:"nyc"}
tex_doc = render_to_string('test.tex', params)
Ex generating as pdf)
pdflatex = PDFLatex(texfile=tex_path,outputdir=pdf_path)
pdflatex.transform()
Latex has a somewhat annoying, difficult learning curve but if you put in the time you can learn what you need to know in order to create these pdfs.
Hope this helps.

The SDAPS framework was designed for scenarios like this: It aids in batch-processing PDF-based forms, extract contents from designated fields and e.g. funnel those into a database for further processing.

How do i output a dynamically generated web page to a .html page instead of .py cgi page?

So ive just started learning python on WAMP, ive got the results of a html form using cgi, and successfully performed a database search with mysqldb. I can return the results to a page that ends with .py by using print statements in the python cgi code, but i want to create a webpage that's .html and have that returned to the user, and/or keep them on the same webaddress when the database search results return.
thanks
paul
edit: to clarify on my local machine, i see /localhost/search.html in the address bar i submit the html form, and receive a results page at /localhost/cgi-bin/searchresults.py. i want to see the results on /localhost/results.html or /localhost/search.html. if this was on a public server im ASSUMING it would return .../cgi-bin/searchresults.py, the last time i saw /cgi-bin/ directories was in the 90s in a url. ive glanced at addhandler, as david suggested, im not sure if thats what i want.
edit: thanks all of you for your input, yep without using frameworks, mod_rewrite seems the way to go, but having looked at that, I decided to save myself the trouble and go with django with mod_wsgi, mainly because of the size of its userbase and amount of docs. i might switch to a lighter/more customisable framework, once ive got the basics

First, I'd suggest that you remember that URLs are URLs and that file extensions don't matter, and that you should just leave it.
If that isn't enough, then remember that URLs are URLs and that file extensions don't matter — and configure Apache to use a different rule to determine that is a CGI program rather than a static file to be served up as is. You can use AddHandler to add a handler for files on the hard disk with a .html extension.
Alternatively, you could use mod_rewrite to tell Apache that …/foo.html means …/foo.py
Finally, I'd suggest that if you do muck around with what URLs look like, that you remove any sign of something that looks like a file extension (so that …/foo is requested rather then …/foo.anything).
As for keeping the user on the same address for results as for the request … that is just a matter of having the program output the basic page without results if it doesn't get the query string parameters that indicate a search term had been passed.