Python Lover(1)Python and Django Introduction
Recently I notice that python is popular in some companies. And I use django and python in year 2010, that is long time ago, I am missing that days.
So I will try to pick my python and django knowledge again.
1. Python
Go to Python website and download the latest package https://www.python.org/ftp/python/3.4.1/python-3.4.1-macosx10.6.dmg
>python3 -V
Python 3.4.1
>python -V
Python 2.7.5
2. Django
https://www.djangoproject.com/download/
Get the latest version https://www.djangoproject.com/m/releases/1.7/Django-1.7.tar.gz
Unzip and link this directory to my working place.
>cd /opt/django
>sudo pythonsetup.pyinstall
Proof the installation
>python3
>import django
>print(django.get_version())
1.7
3. Try to Pick up my Old 2010 django and python knowledge
Some documents from Here
https://docs.djangoproject.com/en/1.7/
Verify the Installation
>python -c "import django;print(django.get_version())"
1.7
Build a poll application
Create the Project
>django-admin.py startproject easypoll
__init__.py means that this directory is Python package.
WSGI is the Web Server Gateway Interface
database configuration is in settings.py
DATABASES = {
'default': {
'ENGINE': 'django.db.backends.sqlite3',
'NAME': os.path.join(BASE_DIR, 'db.sqlite3'),
}
}
default django apps
INSTALLED_APPS = (
'django.contrib.admin',
'django.contrib.auth',
'django.contrib.contenttypes',
'django.contrib.sessions',
'django.contrib.messages’, — messaging framework
'django.contrib.staticfiles’, —— static files
)
Prepare the DB
>python manage.py migrate
Operations to perform: Apply all migrations: admin, auth, sessions, contenttypes Running migrations: Applying contenttypes.0001_initial... OK Applying auth.0001_initial... OK Applying admin.0001_initial... OK Applying sessions.0001_initial... OK
Start the Server
This is a lightweight Web Server written purely in Python.
Or start the server with IP and Port
>python manage.py runserver 0.0.0.0:9000
Performing system checks... System check identified no issues (0 silenced). September 13, 2014 - 05:26:37 Django version 1.7, using settings 'easypoll.settings' Starting development server at http://0.0.0.0:9000/
The development Server automatically reloads Python code for each request as needed.
Creating Models
>python manage.py startapp polls
We then have the polls module there. with models.py, tests.py, views.py and admin.py
Choose the IDE http://www.jetbrains.com/pycharm/
The ORM layer is fast and clean to me.
from django.db import models
# Create your models here.
class Question(models.Model):
question_text = models.CharField(max_length=200)
pub_date = models.DateTimeField('date published')
class Choice(models.Model):
question = models.ForeignKey(Question)
choice_text = models.CharField(max_length=200)
votes = models.IntegerField(default=0)
Once this is defined, Django will create a database schema, create a Python database-access API for accessing Question and Choice objects.
Edit the easypoll/settings.py file to install the app polls.
INSTALLED_APPS = (
'django.contrib.admin',
'django.contrib.auth',
'django.contrib.contenttypes',
'django.contrib.sessions',
'django.contrib.messages',
'django.contrib.staticfiles',
'polls'
)
>python manage.py makemigrations polls
Migrations for 'polls': 0001_initial.py: - Create model Choice - Create model Question - Add field question to choice
Check the SQL
>python manage.py sqlmigrate polls 0001
BEGIN; CREATE TABLE "polls_choice" ("id" integer NOT NULL PRIMARY KEY AUTOINCREMENT, "choice_text" varchar(200) NOT NULL, "votes" integer NOT NULL); CREATE TABLE "polls_question" ("id" integer NOT NULL PRIMARY KEY AUTOINCREMENT, "question_text" varchar(200) NOT NULL, "pub_date" datetime NOT NULL); CREATE TABLE "polls_choice__new" ("id" integer NOT NULL PRIMARY KEY AUTOINCREMENT, "choice_text" varchar(200) NOT NULL, "votes" integer NOT NULL, "question_id" integer NOT NULL REFERENCES "polls_question" ("id")); INSERT INTO "polls_choice__new" ("votes", "choice_text", "id") SELECT "votes", "choice_text", "id" FROM "polls_choice"; DROP TABLE "polls_choice"; ALTER TABLE "polls_choice__new" RENAME TO "polls_choice"; CREATE INDEX polls_choice_7aa0f6ee ON "polls_choice" ("question_id");
From the SQL, we saw it backup the data for choice and do the fore key.
Check the issues
>python manage.py check
System check identified no issues (0 silenced).
Migrate the changes into DB
>python manage.py migrate
Operations to perform: Apply all migrations: admin, sessions, polls, auth, contenttypes Running migrations: Applying polls.0001_initial... OK
Play with the ORM API
>python manage.py shell
Python 3.4.1 (v3.4.1:c0e311e010fc, May 18 2014, 00:54:21) [GCC 4.2.1 (Apple Inc. build 5666) (dot 3)] on darwin
Commands on the API
>>> from polls.models import Question, Choice
>>> Question.objects.all() []
>>> from django.utils import timezone
>>> q = Question(question_text="what's new?",pub_date=timezone.now())
>>> q.save()
>>> q.id 1
>>> q.question_text "what's new?"
>>> q.pub_date datetime.datetime(2014, 9, 15, 17, 25, 50, 477263, tzinfo=<UTC>)
>>> q.question_text = "what's up?"
>>> q.save()
>>> Question.objects.all() [<Question: Question object>]
After I change the __str__ method as follow:
def __str__(self):
return '%s %s' % (self.question_text, self.pub_date)
help>
>>> quit() macbook-master:easypoll carl$ python manage.py shell>>> from polls.models import Question, Choice >>> Question.objects.all() [<Question: what's up? 2014-09-15 17:25:50.477263+00:00>]
Very impressive Search on the API
>>> Question.objects.all()
[<Question: what's up? 2014-09-15 17:25:50.477263+00:00>] >>> >>> Question.objects.filter(id=1) [<Question: what's up? 2014-09-15 17:25:50.477263+00:00>] >>> >>> Question.objects.filter(question_text__startswith='What') [<Question: what's up? 2014-09-15 17:25:50.477263+00:00>] >>> >>> from django.utils import timezone >>> current_year = timezone.now().year >>> Question.objects.get(pub_date__year=current_year) <Question: what's up? 2014-09-15 17:25:50.477263+00:00>
Customized Method
>>> from polls.models import Question, Choice >>> >>> >>> q = Question.objects.get(id=1) >>> q.was_published_recently()
Display and Search the Related Objects
>>> q.choice_set.all() [] >>> q.choice_set.create(choice_text='Not Much', votes=1) <Choice: Not Much 1> >>> q.choice_set.create(choice_text='The Sky', votes=2) <Choice: The Sky 2> >>> c = q.choice_set.create(choice_text='The Ground', votes=3) >>> c.question <Question: what's up? 2014-09-15 17:25:50.477263+00:00> >>> q.choice_set.all() [<Choice: Not Much 1>, <Choice: The Sky 2>, <Choice: The Ground 3>] >>> q.choice_set.count() 3 >>> >>> c = q.choice_set.filter(choice_text__startswith='The') >>> c [<Choice: The Sky 2>, <Choice: The Ground 3>]
Really impressive on Django from 2010 to 2014, it improve a lot.
Tip
Upgrade and Install from Sources
Both 1&2 are old from my understanding.
I download the source file from here https://www.python.org/ftp/python/3.4.0/Python-3.4.0.tar.xz
Unzip and try to build on my local machine.
>./configure --prefix=/Users/carl/tool/python-3.4.0
>make
>make altinstall
Soft link this directory to the working place
Edit the .profile File
export PATH=/opt/python/bin:$PATH
>. ~/.profile
>python -V
Python 3.4.0
I do not plan to do source installation.
References:
django 1~8
http://sillycat.iteye.com/blog/573279 Installation and hello world
http://sillycat.iteye.com/blog/573370 CRUD, html template
http://sillycat.iteye.com/blog/575687 session and wiki
http://sillycat.iteye.com/blog/576192 db, import and export
http://sillycat.iteye.com/blog/576864 page and UI
http://sillycat.iteye.com/blog/582074 nginx + fastcgi
http://sillycat.iteye.com/blog/582603 ajax and json
http://sillycat.iteye.com/blog/583993 Tag
https://docs.djangoproject.com/en/1.7/
https://www.djangoproject.com/download/
http://www.swoole.com/Twisted.html
http://blog.sina.com.cn/s/blog_704b6af70100py9n.html
http://twistedmatrix.com/trac/wiki