Develop Reference

How to create a sample django project?

This doesn't work for me.
$ python django-admin.py startproject myproject
I am running a ubuntu virtual m/c on my windows system.
By default ubuntu 12.04 comes with python 2.7.3 so I am using that only
I downloaded or installed (whatever it does since I am new to django) by issuing the following command-
git clone https://github.com/django/django.git
django directory is successfully created.
I want to create a sample django application. So for this I am issuing the following command-
$ python django-admin.py startproject tango_with_django_project
Obviously, it will throw error since the default ubuntu python doesn't know that django has been installed.
My Question is how to integrate python with this Django and create a sample django application?

The comments above pointing you to the documentation are of course correct, but there are also other resources that can help you start your site the 'right' way. In particular, cookiecutter and its related Django template will get you set up with some really good defaults and valuable third-party apps straight away. If you have cash to spend I'd also heartily recommend the book Two Scoops of Django, by the people who wrote the two applications to which I've linked.
Jeff Knupp has also written a thoroughly useful blog post on starting a Django project the right way, which covers useful topics such as the importance of:
source control;
automated testing (see also this excellent book);
isolating your development environment to smooth deployment; and
managing your database with migrations (included in Django since version 1.7).

Getting Django 1.7 to work on Google App Engine

Can anyone help to point us to instructions on how to get Django >1.5 working on Google App Engine? I have seen a number of people claim they have Django 1.6 working. We'd like to get 1.6 or 1.7 running. I have searched here for instructions on how to set this up. No luck so far.
Update:
In our development machine we have Django 1.7 installed (both /user/local and on virtualenv). However, if we modify GAE yaml to use Django 1.7 we get the following error messages:
google.appengine.api.yaml_errors.EventError: django version "1.7" is not supported, use one of: "1.2", "1.3", "1.4", "1.5" or "latest" ("latest" recommended for development only) in "./app.yaml",
The version 1.9.12 GoogleAppEngine sdk install in our /Applications/GoogleAppEngineLauncher.app/Contents/Resources/GoogleAppEngine-default.bundle/Contents/Resources/google_appengine/lib directory shows the following Django versions listed:
django-0.96 django-1.2 django-1.3 django-1.4 django-1.5
My question is related to how to get our development environment setup correctly for Django 1.7 on Google App Engine and how to make sure we successfully deploy our app with Django 1.7 when we deploy to Google App Engine in production. How do we get the Django 1.7 to deploy on GAE when we deploy our app?

You can use any pure Python third party libraries in your Google App Engine application. In order to use a third party library, simply include the files in your application's directory, and they will be uploaded with your application when you deploy it to our system. You can import the files as you would any other Python files with your application.
I have application using Django 1.7 this way and everything is working fine. However, sometimes you may need to sort of hack something due to the App Engine limitations and its specifics. But it depends on your use cases.
I would also suggest to use virtual environment for your project. Install each library that is not supported by App Engine directly via pip and then create a symlink in your application directory pointing to the given library.
This way you can keep all required packages in a file (e.g. requirements.txt) that can be stored in SCM system (e.g. Git) along with your source files and other team members can quite easily replicate your working environment.
Provided that you use virtual environment and install all needed libraries (Django, ...) via pip, here is the directory layout that should work for you.
virtual-env-root
.Python
bin
include
lib
app-engine-project-root
app.yaml
django-project-root
django-app-root
symlink-to-django -> lib/python2.7/site-packages/django
symlink-to-another-lib -> lib/python2.7/site-packages/...
Such a layout can be easily deployed with the below command.
$ appcfg.py update app-engine-project-root
Or tested with App Engine development server.
$ dev_appserver.py app-engine-project-root
UPDATE
Since App Engine Python SDK version 1.9.15 you can use the vendoring mechanism to set up third party libraries. You do not have to create symlinks in your application directory pointing to the Python lib folder anymore.
Create lib directory directly in your application root and tell your app how to find libraries in this directory by means of appengine_config.py file.
from google.appengine.ext import vendor
# Add any libraries installed in the "lib" folder.
vendor.add('lib')
New directory layout follows.
virtual-env-root
.Python
bin
include
lib
app-engine-project-root
lib
app.yaml
appengine_config.py
django-project-root
django-app-root
Use pip with the -t lib flag to install libraries in this directory.
$ pip install -t lib [lib-name]
Or
$ pip install -t lib -r requirements.txt

You cannot - GAE only supports 1.5, and even that is marked as experimental. If you need django 1.7, perhaps you should use Google Compute Engine, which is Google's brand name for virtual machines that you can spool up.
If you are not married to Google App Engine, Heroku supports django 1.7 without issues.
Do you have specific a guide on how to move a Django 1.7 project to
Google Compute Engine? There is a bunch of Google stuff without any
guides on how to make them work.
Here are the steps, but they are the same had you deployed on any other server because GCE just gives you a linux instance:
First, make sure your developer account has a billing method attached to it.
Go to the developer console
Create a new project by clicking on Projects, then Create Project.
Wait as the project is being created (you'll see a progress window on the bottom right of your screen).
Once the project is finished creating, the console will automatically shift to that project's settings:
You can create a new instance, or deploy a ready-made template from the second column. You can see there are popular stacks and software applications for which templates are created.
As there is no django template yet, you will start by creating an instance.
Billing is controlled on a per-project basis, so you'll have enable billing at this point if you haven't done so already.
The next page is where you configure the instance. The fields are self-explanatory. You set the type of machine you like (how many virtual CPUs and memory), where (physically) you prefer the machine to be located, if you want both HTTP and HTTPS ports open, and then a disk image from which the instance will boot:
Once you have configured the machine, it will be brought online booted up and then you'll have access to the terminal via SSH.
From this point forward, you should treat this instance like any linux server. Install whatever you need to make your project work using the normal packaging tools; upload your files, etc.
For Amazon, the process is a bit simpler as there is a large library of AMIs that you can use for a one-click deployment process. AMI is Amazon Machine Image - a template from which you can deploy an instance.
For Heroku, as its a PaaS, you don't have to worry about the hardware components; however as with most PaaS platforms, you don't have write access to the filesystem. So to manage your static assets you have to do some extra work. The easiest option is to create a S3 bucket on Amazon and use that with django-storages. The official django tutorial at heroku suggests the use of dj-static to serve files directly from Heroku. This works fine for testing, but if you want to start uploading files, then you need to handle those correctly.
However, once you sort that out the steps are even simpler:
Pre-requisites:
git
heroku toolbelt
dj-database-url Python package
gunicorn Python package
The basic steps:
Create a git repository (if you have not done already) in your source code directory with git init.
Create a requirements.txt at the root of your project. pip freeze > requirements.txt should do it if you are using a virtual environment. Otherwise, you can create a text file and list the packages you need.
Adjust your settings.py, by adding this line at the very bottom: import dj_database_url
DATABASES['default'] = dj_database_url.config()
Create a Procfile (case is important). This is how you tell Heroku what kind of dyno (process) you need for your application. For django, you need a web dyno so in this file the following line should do: web: gunicorn yourproject.wsgi --log-file -
Create an app on Heroku and deploy. You should run these commands from your source code directory:
heroku create --buildpack https://github.com/heroku/heroku-buildpack-python
heroku addons:add heroku-postgresql:dev
git push heroku master
heroku run python yourproject/manage.py migrate --noinput
heroku run python web/manage.py collectstatic
You only do the first two steps once, then whenever you need to update your application simply git push heroku master to create a new revision on Heroku.

App Engine's Python environment currently knows how to provide Django up to version 1.5 via the libraries: configuration mechanism. This doesn't mean that later versions of Django won't work, only that they aren't yet built in. (I'm not sure why the latest built-in version is 1.5. It may have something to do with AE's historical policy of bundling each supported version of Django with the SDK, which probably needs to be revised to keep the SDK from getting too large.)
You can try to include Django 1.7 with your application files. I haven't tried this with 1.7 specifically yet, but it's worked with previous versions. Some adjustments to sys.path will be needed in your main.py.
Note that there is a limit of 10,000 application files. If you're concerned about this limit, one option is to use Python's zipimport and include Django as a zip archive. https://docs.python.org/2/library/zipimport.html

python django project and folder structure (differing from WAMP)

I have my development environment setup on Win 7 like this:
Django development structure
Apache -server- C:\Program Files (x86)\Apache Software Foundation\Apache2.4
PostgreSQL -database- C:\Program Files\PostgreSQL\9.2
Django -framework- C:\Python27\Lib\site-packages\django
Python -code- C:\Python27
Project -root- C:\mysite
|----------apps
|----------HTML
|----------CSS
|----------JavaScript
|----------assets
I am attempting to keep this extremely simple to start out. There are 5 main directories each with a distinct purpose. All the code resides in the project folder.
compared to WAMP structure:
C:\WAMP
|----------C:\Apache
|----------C:\MySQL
|----------C:\PHP
|----------C:\www
I like how Apache, MySQL, and PHP all reside in a neat directory. I know to keep the root project OUTSIDE in another directory in Django for security reasons.
Is it fine that Apache, PostgreSQL, and Python are installed all over the place in the Django environment?
Did I miss a core Django component and/or directory?
Will deploying and scaling be a problem?
I want this to be a guideline for beginning Django web programmers.

I can answer the question one by one:
Is if fine that Apache, PostgreSQL, and Python are installed all over the place in the Django environment?
All over the place sounds weird but yes it is totally fine.
Did I miss a core Django component and/or directory?
No you don't miss anything, Django core is in site-packages folder already and your site code is mysite, which can be located anywhere you want.
Will deploying and scaling be a problem?
No it won't be a problem with current structure. You will deploy your mysite only, the other will be installed separately.
Something you should get familiar with when starting with Django development:
Most likely when you deploy your project, it will be on a Linux server, so install and learn Linux maybe?
virtualenv: Soon you will have to install Django, then a bunch of external packages to support your project. virtualenv helps you isolate your working environment. Well it's "unofficial" a must when you start with python development.
virtualenvwrapper to make your life easier when working with virtualenv
git and github or bitbucket: if you don't know git yet, you should now.

Apache is just web server, it is used to serve files, but to make a website you do not necessary need it. Django comes with its own development server. See :
python manage.py runserver
Apache is required when you are developing PHP websites because your computer do not know how to compile and interpret it. But for Django, you use the Python language, and you have already install it if you are using Django.
Read https://docs.djangoproject.com/en/1.5/intro/tutorial01/
And where it will be the time to set up your own server using Apache look at :
https://docs.djangoproject.com/en/dev/howto/deployment/wsgi/modwsgi/.

Scaling will be a problem on windows. Python in Apache on windows gets 64 threads in one process. Couple this with the GIL and you will have scaling issues.
Python and Apache on Linux don't have this same problem. Under Linux wsgi can create multiple processes that have multiple threads each, minimizing GIL issues.
WSGI in Apache on windows is not a scalable solution in my opinion.
However you can develop there and move to linux for deployment, I do it all the time.
You will want to take advantage of the Apache Alias directive to serve all your static content like css, js, favicon.ico. This frees up python to only handle requests that require logic.

How to install the django site (tar.gz) downloaded from internet

I have downloaded this project http://code.google.com/p/django-budget/
How can i install it. Do i need to execute some commands or just extract it to some folder.
DO i need to use syncdb.
I am newbie so don't know much

PS. It's been moved to https://github.com/toastdriven/django-budget for a while now.
There is information on the frontpage of the site:
Installation
Either copy/symlink the budget app
into your project or place it
somewhere on your PYTHONPATH.
Add the budget.categories,
budget.transactions and budget apps to
your INSTALLED_APPS.
Run ./manage.py syncdb.
Add (r'^budget/',
include('budgetproject.budget.urls')),
to your urls.py.
You need Python and Djano installed.

How to re-use a reusable app in Django

I am trying to create my first site in Django and as I'm looking for example apps out there to draw inspiration from, I constantly stumble upon a term called "reusable apps".
I understand the concept of an app that is reusable easy enough, but the means of reusing an app in Django are quite lost for me. Few questions that are bugging me in the whole business are:
What is the preferred way to re-use an existing Django app? Where do I put it and how do I reference it?
From what I understand, the recommendation is to put it on your "PYTHONPATH", but that breaks as soon as I need to deploy my app to a remote location that I have limited access to (e.g. on a hosting service).
So, if I develop my site on my local computer and intend to deploy it on an ISP where I only have ftp access, how do I re-use 3rd party Django apps so that if I deploy my site, the site keeps working (e.g. the only thing I can count on is that the service provider has Python 2.5 and Django 1.x installed)?
How do I organize my Django project so that I could easily deploy it along with all of the reusable apps I want to use?

In general, the only thing required to use a reusable app is to make sure it's on sys.path, so that you can import it from Python code. In most cases (if the author follows best practice), the reusable app tarball or bundle will contain a top-level directory with docs, a README, a setup.py, and then a subdirectory containing the actual app (see django-voting for an example; the app itself is in the "voting" subdirectory). This subdirectory is what needs to be placed in your Python path. Possible methods for doing that include:
running pip install appname, if the app has been uploaded to PyPI (these days most are)
installing the app with setup.py install (this has the same result as pip install appname, but requires that you first download and unpack the code yourself; pip will do that for you)
manually symlinking the code directory to your Python site-packages directory
using software like virtualenv to create a "virtual Python environment" that has its own site-packages directory, and then running setup.py install or pip install appname with that virtualenv active, or placing or symlinking the app in the virtualenv's site-packages (highly recommended over all the "global installation" options, if you value your future sanity)
placing the application in some directory where you intend to place various apps, and then adding that directory to the PYTHONPATH environment variable
You'll know you've got it in the right place if you can fire up a Python interpreter and "import voting" (for example) without getting an ImportError.
On a server where you have FTP access only, your only option is really the last one, and they have to set it up for you. If they claim to support Django they must provide some place where you can upload packages and they will be available for importing in Python. Without knowing details of your webhost, it's impossible to say how they structure that for you.

An old question, but here's what I do:
If you're using a version control system (VCS), I suggest putting all of the reusable apps and libraries (including django) that your software needs in the VCS. If you don't want to put them directly under your project root, you can modify settings.py to add their location to sys.path.
After that deployment is as simple as cloning or checking out the VCS repository to wherever you want to use it.
This has two added benefits:
Version mismatches; your software always uses the version that you tested it with, and not the version that was available at the time of deployment.
If multiple people work on the project, nobody else has to deal with installing the dependencies.
When it's time to update a component's version, update it in your VCS and then propagate the update to your deployments via it.