Setup¶
Installing Django¶
Pip is a way to install python code. Python code is installed as a package.
To list all currently installed python packages:
$ pip freeze
To install a Django:
$ pip install django
Creating Django project¶
We use a script supplied by django to set up a new project:
$ django-admin.py startproject website
You should see this folder structure and files generated:
website
├── manage.py
└── website
├── __init__.py
├── settings.py
├── urls.py
└── wsgi.py
The important files are manage.py, settings.py, and urls.py.
settings.py¶
A lot of configuration is needed to setup a web application.
website/settings.py contains a lot of names that define all the configuration for our website. All the defaults are good for now.
Note the INSTALLED_APPS name is defined as a tuple of strings. We will be adding to that tuple shortly.
Note also the DATABASES name is defined as a dictionary.
Creating the Database¶
Notice that the current directory doesn’t include a db.sqlite3 file.
Django like all web frameworks stores its data in a database. Lets create that database now:
python manage.py syncdb
You will see some output such as: Creating table auth_user
(django) website $ ./manage.py syncdb
Creating tables ...
Creating table django_admin_log
Creating table auth_permission
Creating table auth_group_permissions
Creating table auth_group
Creating table auth_user_groups
Creating table auth_user_user_permissions
Creating table auth_user
Creating table django_content_type
Creating table django_session
You just installed Django's auth system, which means you don't have any superusers defined.
Would you like to create one now? (yes/no): yes
Username (leave blank to use 'greg'):
Email address:
Password:
Password (again):
Superuser created successfully.
Installing custom SQL ...
Installing indexes ...
Installed 0 object(s) from 0 fixture(s)
Now the top level folder website contains a file called db.sqlite3. This is your database.
Inspecting the Database¶
Download sqlite3 from www.sqlite.org/download.html. Choose the sqlite-shell-win32-x86-....zip file. Unzip it by double clicking it. Then drag and drop into C:BOOTCAMPPython34The last step is to add it to a directory on the PATH.
A database application is like a server.
We send requests using clients. The clients in this case aren’t the browser but typically programs such as our python website.
We will use another server to independently inspect our database.
You launch the client by typing:
sqlite3 db.sqlite3
The sqlite3 program provides a new type of shell which is meant for inspecting our database.
Here is an example interaction:
(django)➜ website sqlite3 db.sqlite3
SQLite version 3.7.13 2012-07-17 17:46:21
Enter ".help" for instructions
Enter SQL statements terminated with a ";"
sqlite> .tables
auth_group auth_user_user_permissions
auth_group_permissions django_admin_log
auth_permission django_content_type
auth_user django_session
auth_user_groups
sqlite> select * from auth_user;
1|pbkdf2_sha256$12000$YqWBCAkWemZC$+hazwa/dPJNczpPitJ2J0KR8UuAX11txLlSkrtAXk5k=|2014-08-21 14:59:05.171913|1|greg||||1|1|2014-08-21 14:59:05.171913
sqlite>
The .tables command lists all the tables that exist in the database. We recognise these as being the same that were created earlier by running the .manage.py syncdb command.
The select * from auth_user; is SQL. SQL is a language dedicated to programming databases. This command means give me everything in the auth_user table.
Type:
sqlite3> .quit
To exit.
Running the server¶
You run the server with:
./manage.py runserver
Now you can send http requests using your browser as client. Enter:
http://127.0.0.:8000/
You should see:
You can quit the server at any point by pressing together cntrl + c
Creating & installing the Blog App¶
Tip:
Django like any framwork, provides a way of organising your code. It provides in effect a proven architecture which you learn to work within.
A good webframework makes a lot of decisions for you. You build on the combined experience of the developpers who created it.
Django introduces the concept of an app as a way to organise code.
Our Blog will be an app. We create it thusly:
./manage.py startapp blog
We now have a foler directory generated looking like:
├── blog
│ ├── __init__.py
│ ├── admin.py
│ ├── models.py
│ ├── tests.py
│ └── views.py
├── db.sqlite3
├── manage.py
└── website
├── __init__.py
├── settings.py
├── urls.py
└── wsgi.py
We now need to tell our website about the blog apps’ existence. We do this by adding it to the INSTALLED_APPS tuple.
INSTALLED_APPS = (
'django.contrib.admin',
'django.contrib.auth',
'django.contrib.contenttypes',
'django.contrib.sessions',
'django.contrib.messages',
'django.contrib.staticfiles',
'website',
'blog',
)