Ensure that a path to a dir is a Django project - python

For the last two days I am struggling with the following question:
Given an absolute path (string) to a directory (inside my file system or the server, it doesn't matter), determine if this dir contains a valid Django project.
First, I thought of looking for the manage.py underneath, but what if some user omit or rename this file?
Secondly, I thought of locating the settings module but I want the project root, what if the settings is 2 or more levels deep?
Third, I thought of locating the (standard) BASE_DIR name inside settings, but what if the user has not defined it or renamed it?
Is there a way to properly identify a directory as a valid Django project? Am I missing something?

One way you can try is searching/reading the.py files in the directory and match with regex a pattern describing
the distinctive django main function and package names.
Might be lucrative, but... eh

As bruno desthuilliers mentioned in the comments, there is no fail-safe solution.
But it depends on what do you need it for. I mean, how strict it has to be (or how good?). I have seen a few times the usage of PROJECT_DIR instead of BASE_DIR. And about the settings, I've seen single settings.py file and several settings files within a settings directory.
The main challenge would be Django not having that much hard naming rules for files/modules. You can pretty much name your files whatever, as far as you put the pieces together properly.
If I'm not mistaken, the only hard rule Django has is the models.py file. A Django app must have a file named models.py. But, your Django application doesn't necessarily need to have any app installed.
If you only need a good enough solution, I would say manage.py is a good candidate. You could double check and open the file and see if there's a django import there. If no manage.py, check if there's a requirements.txt and check if Django is listed there. If no requirements.txt, check for a directory named requirements and for text files within.
Something you could do to find some patterns is browsing the repositories tagged as with "django" tag on GitHub. Maybe use their API and clone all repositories (it will only list the top 2000 repos) to your local machine or to a server. Clone some rails, javascript, etc. repos as well and write your code step by step. Just search for a manage.py, if the result is satisfatory, that's it. If not, add a couple of more rules and test against the cloned repositories until you find a good enough solution for your problem.

Related

Django : Why should I add package name inside INSTALLED_APPS?

In Djano, why should I add third-party package names inside the INSTALLED_APPS for some packages such as django-filter, DRF, debug-toolbar etc, while I don't want to add for some packages such as Celery, Requests etc ?
I couldn't figure out why should add them to a specific list, even though they all are similar pip packages and I installed them in the same way. Thanks in advance!
From docs :
Package? App?
A Python package provides a way of grouping related Python code for
easy reuse. A package contains one or more files of Python code (also
known as “modules”).
A package can be imported with import foo.bar or from foo import bar.
For a directory (like polls) to form a package, it must contain a
special file init.py, even if this file is empty.
A Django application is just a Python package that is specifically
intended for use in a Django project. An application may use common
Django conventions, such as having models, tests, urls, and views
submodules.
From above statements we understand that every well-written python code could be a package, now if this package is a bunch of python code in a directory, installing it would mean just copy the directory in your project and import them wherever needed in code.
But now there is this package which was already a django app and maybe used some special advantages of being one. Like exposing a restful API or delivering some sort of static resources or even working with special django-specific classes. these kind's of operation's need your direct permission in settings.py so that your project will know how to deal with this package. or even they may require to include their url path's to your project so that people visiting your site could access them.
I assume all this manual job is an act of security.
You need to add apps with models(non-abstract), templates, templatetags or management commands so that django-admin finds and loads them

Python library with config file

I would like to gather many libraries I have made while working on my projects in some kind of container, so that I can easily use any of them in future projects of mine. It is pretty clear to me how to do this, except one part.
I am assuming that every service will have its own config file (for instance, the Cache service, will have a config file with cache host and port, and so on). Now the problem is: when I want to use this container in an arbitrary project I will have to make assumptions about the project directory structure to know where to find these config files.
For instance, one might assume that on the same path of my library there is a config folder where I will find the config files of my services. However, this might conflict with the project's directory structure (i.e. the project might already have its own config directory for instance).
So, all in all, my question is: is there a safe, standard way to ship a library which might assume to find some config files someplace, or for which example config files are shipped along with the library itself?
well, you should not keep config files, or anything that you want to modify along with code in python (or actually in any language). Each OS have folders for that purpose.
Either it's system wide, and on Unix it's /etc or it's for an user it's in ~/.config. You have theLibrary folders for OSX, and I'm sure there's something alike for windows beyond \Windows\SYSTEM32 😉.
What that means is that the path to your configuration files shall not be considered relative to your code at any point. Never. Ever.
You can include some assets in a python package, using the MANIFEST.in but, as it'll be within your python package, you shall assume you won't have rights to write where it'll be (installed by admin, ran by user).
You can also specify some of those assets to install at specific places using setup.py's data_files directive, which will be installed relatively to sys.prefix.
Common practice is to provide configuration files examples using a link from the documentation, or better generate those files when starting the application.
Also, another trend for desktops, is to use the XDG directory specification, to decide where to look for, or where to place your configuration files.
To sum it up:
make a list of default paths your code expects to find the configuration,
make it possible to specify manually at command line the path to the configuration python foo.py --config bar.ini
write a feature for your tool to generate the configuration (with a series of questions)
deploy your default configurations to standard places (XDG paths, $prefix/etc…)

Most efficient solution for sharing code between two django projects

I have to find a solution for sharing code between two big Django projects. The main things to share are models and serializers and template tags. I've came up with 3 different solutions and I need you to find pro and cons to be able to make a choice.
I'll list you the solutions I found:
git submodules
Create a repository where to store my *.py files and include them as a django app such as 'common_deps'
Even if this is the purpose of git submodules there are a bit hard to use and its easy to fall into traps.
python package
Create a python package to store my *.py files.
It seems to be the best option to me event if that means that I'll need to change my requirements.txt file on my projects on each new release.
Simple git repository
Create a new repository to store my *.py files and include them as a django app such as 'common_deps'. Then add it to my PYTHON_PATH
I need some advices, I haven't chosen yet. I'm just telling myself that git submodules seems to be a bas idea.
Tell me guys.
I will definitely go with the second option you listed - packaging your app. If you follow steps in the Packaging your app part of official Django tutorial, you'll get tar.gz file which will allow you to include your app in any project you want by simply installing (e.g. with pip) to the virtual env connected with the project or globally
I will go with python package, after all this is what it is for.

How to override an app in Django properly?

I'm running Satchmo. There are many apps and I've changed some of the source in the Product app.
So my question is how can I override this properly because the change is site specific. Do I have to copy over the whole Satchmo framework and put it into my project or can I just copy one of the apps out and place it in say Satchmo>App>Products? (Kinda like with templates)
Thanks
What I have done which works is to copy the application that I have changed. In this case satchmo\apps\product.
I copied the app into my project folder
Amended my setting.py INSTALLED_APPS from 'product', to 'myproject.product',
This now carries the changes I've made to this app for this project only and leaves the original product app untouched and still able to be read normally from other projects.
When you add a 'Django App' to INSTALLED_APPS in your settings.py file, you're telling Django that there exists an importable python module with that name on your "python path". You can view your python path by viewing the contents of the list stored at sys.path.
Whenever Python (and in this case Django) attempts to import a module it checks each of the directories listed in sys.path in order, when it finds a module matching the given name it stops.
The solution to your problem then is too place your customized Django Apps, e.g., the Satchmo product module, into a location in your python path which will be checked before the "real" Satchmo product module.
Because I don't know how you have your directory structure laid out I'm basically making a guess here, but in your case, it sounds like you have the Satchmo apps living somewhere like /satchmo/apps/ and your project at /my_custom_path/my_project/. In which case you might want to add your customized product module to /my_custom_path/my_project/product/. Because the path at which your Django settings.py file lives is always checked first, that should mean that your customized product module will be found first and imported instead of the built in Satchmo one.
FYI: To check and see the order in which your Satchmo installation is checking directories for modules run python manage.py shell and then in the prompt do import sys; print sys.path.
Normally, I'd say the best thing is to fork Satchmo and keep a copy with your changes.
If you are willing to play with the python path, make sure that your app's directory appears before the other (default) directory. From my tests, if you have two apps/modules with identical names, the first one found is used.

paths not being consistent python django

I'm trying to import sorl-thumbnail into my app in django. Now the way that I have the site set up, using mod_wsgi on CentOS 5 with cpanel, the path for the apps must have the project name when importing... which is a pain.
Obviously this is a cause of concern with portability of the app. I'm importing sorl-thumbnail, in previous apps I've just added sorl.thumbnail to the installed apps and it's worked.
However now it's causing issues unless I have the project name www. in front of the import path. It's never done this before and I can't seem to get around the path issue.
I've added www.sorl.thumbnail also but then the rest of the paths in the sorl files have errors. Any ideas on how to remedy this or fix a work around?
You shouldn't need to use the project name when importing - just make sure that the apps are somewhere on your python path. Something along the lines of:
sys.path.append('/etc/django/domains/mydomain.com/myproject/')
... in your .wsgi file should do it (with the path to your own project, of course).
Ideally reusable apps should be outside of your project directory anyway, so consider creating a folder such as '/etc/django/lib/' to contain reusable apps and appending that to sys.path in your wsgi handler too.
Or, if you don't like that, perhaps use virtualenv and add your reusable apps directly to site-packages.
Or, if you don't like that, put your reusable apps somewhere else and symlink them to site-packages or somewhere on your python path.
In short, just make sure the package/module you're importing is on your python path. If you find yourself adding the project name or 'www' to a bunch of import paths, then you're probably doing something wrong.

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