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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.

How do I find out what I can do with the Pelican signals? I'm trying to write a plugin

The signals are sort-of described here but, then what?
For example, one of the signals is desribed:
invoked before writing each article, the article is passed as content
How do I change that content? How do I access it? What functions are available?
I've been looking at examples in the pelican plugins repo on github, but I'm still confused. (How did those people even learn how to write those plugins?)
I hardly know where to start.

You have to look at the source code of pelican. I think there is no better way.
For example, search for the signal you are interested in, e.g. article_generator_write_article: https://github.com/getpelican/pelican/search?utf8=%E2%9C%93&q=article_generator_write_article
Then, look into the search result, e.g. generators.py and click on the line number containing your signal. Of course, you could also create a clone and do all this locally. This depends on your way of working.
Surrounding code:
def generate_articles(self, write):
"""Generate the articles."""
for article in chain(self.translations, self.articles):
signals.article_generator_write_article.send(self, content=article)
write(article.save_as, self.get_template(article.template),
self.context, article=article, category=article.category,
override_output=hasattr(article, 'override_save_as'), blog=True)
As you can see, the signal call provides you with an article object. You can now 1) look in the source code to find the respective python class of this object to find out about its inner workings, methods and attributes or 2) go the hacky path and simply print the object's members print(article.__dict__).
I suppose, without having looked in the code, that article has an attribute content which contains the HTML code generated from your source file. This is where your desired change comes in.
Note that if you want to change the source code before processing this is not that easy. I just wrote a little plugin which is capable of doing this.
There you can also see the signal API in action. You simply have to connect a handler function to the desired signal.
I hope this helps :)

Gallery in Photologue can have only one Photo

after I put the photologue on the server, I have no issue with uploading photos.
the issue is when I am creating a Gallery from the admin site, I can choose only one photo to be attached to the Gallery. even if I selected many photos, one of them will be linked to the Gallery only.
The only way to add photos to a gallery is by adding them manually to photologue_gallery_photos table in the database :(
anyone kows how to solve it?

I had exactly the same problem. I suspected some problem with django-sortedm2m package. To associate photo to gallery, it was using SortedManyToMany() from sortedm2m package. For some reason, the admin widget associated with this package did not function well. (I tried Firefox, Chrome and safari browser).
I actually did not care for the order of photos getting uploaded to Gallery, so I simply replaced that function call with Django's ManyToManyField(). Also, I noticed that SortedManyToMany('Photo') was called with constant string Photo. Instead it should be called with SortedManyToMany(Photo) to identify Photo class. Although it did not resolve my problem entirely. So I used default ManyToMany field and it is showing all the photos from Gallery.

I guess your problem is solved by now, but just in case.. I had the same problem. Looking around in the logs, I found it was caused by me not having consolidated the static files from sortedm2m with the rest of my static files (hence the widget was not working properly).

Make sure sortedm2m is in INSTALLED_APPS in addition to photologue; merely duplicating any sortedm2m templates alone will not suffice.
Installation & configuration — django-photologue 3.6 documentation

update text within html

So I have a python webapp on Google App Engine and am using the jinja2 template engine. I have a lot of text on the site that I want to update regularly, such as news sections and updates about the site.
What is the most efficient way to go about doing this? Clearly the simplest short-term solution and what I am currently doing is just to change the HTML but I would like to give others access to this without giving them access to the server side of things.
Should I just bite the bullet and write a interface on an admin page that allows users to edit it and then the server takes this and renders it in the News section? Any suggestions or tips would be great!

What you are thinking about, and moving toward (whether you know it or not) is called a content management system.
Most of them store content in a database and provide a user interface to allow editing it, just as you're designing.
Perhaps you could use off-the-shelf parts? I don't know exactly which ones are appengine-based, but this is a very common task and I'm sure you'll save time by using others' work.

I have created a very basic jinja CMS to maintain Jinja (page) blocks. You can find it here: https://codereview.stackexchange.com/questions/5965/review-request-jinja-cms-for-energiekantoor-nl-on-google-app-engine

Getting information about static files in Python App Engine; workarounds

I'm working on an App Engine project that will have customizable themes. I'd like to be able to use jQuery UI themes. The problem is figuring out what the CSS file is going to be named. (Typically, "jquery-ui-1.7.2.custom.css". Version numbers will change, and people tend to rename things, but there should only be one CSS file, and I'm OK with it being an error condition if there's two or more for some reason.) Because it's a static file (static files are uploaded to App Engine separately from the rest of the application's resources), I can't just glob the directory for a CSS file. I can't just assume that it's hard-coded, and I really don't want to make it a configuration setting, because that's a bad user experience.
Guido told me to symlink it so that App Engine sees two copies and can treat one as static and the other as an application resource, but symlinks don't work on Windows, and since this will ultimately be open source, I can't control which SDK the user uses. Another suggestion was to use a deploy-time script, but Mac users have this nice "Deploy" button in their version of the SDK and I'd rather not have to tell them, "Oh hey, sorry for the inconvenience, but you can't use that for this project."
I clearly need an out-of-the-box solution to this one, but I'm at a loss. Anyone have any good suggestions for how to get a custom jQuery UI theme out of the ThemeRoller and into an App Engine app? Some post-processing is already needed, because the only files in the zip file that ThemeRoller gives you are in the "css" directory. Maybe I can write something that takes a raw theme as input and spits out something useful on the other side (the deploy-time script trick, but somehow less user-unfriendly). The trick here is presentation — I want the user to spend as little time on the command line as possible. An ideal solution assumes the person performing this task is non-technical for the most part. No part of the solution can be much harder than installing something like WordPress or Drupal, and in a perfect world, it should be way, way easier.

To accomplish what you are asking, I would use the datastore for serving the CSS files. Since this would allow easy listing, sorting and even modification and uploading.
Other than that, your next best options would be to store the CSS data inside a script (a dictionary where the filename is the key name, and the CSS code is the value). Or, as you suggested, to run a script before deploying to AppEngine.
Personally, I would go for the storing in the datastore option, since it will allow for a great deal more user customization (such as each user being able to provide their own CSS file), just be sure to use memcache to avoid needing to access the datastore when possible (which should be a very common occurrence), as well as using HTTP headers to tell the browser to cache the CSS file locally.