[PYTHON] From 0 to Django development environment construction to basic operation

Since it is a memorandum & personal use, it is written quite simply. I think beginners should also refer to other articles.

Version note

I mainly worked with python 2.7.10 and Django 1.6. Please note the following points when working with python 3 series, Django 1.9

Select the appropriate version when $ pyenv install Select the appropriate version when $ pip install django. (The latest 1.9 is included by default)

It feels like a database is created in one shot after writing a model with Django 1.6 $ python manage.py syncdb. After writing the model as 1.9 After making a migration file with $ python manage.py makemigrations app name It feels like creating a DB from a migration file with $ python manage.py migrate.

That's it (probably).

1. Environment construction

1-1. Install pyenv

Install from GitHub

$ git clone https://github.com/yyuu/pyenv.git ~/.pyenv

(~ / .pyenv is the local directory name. Make it an appropriate name) Write pyenv settings to zshenv, bash_profile, etc.

export PYENV_ROOT=$HOME/.pyenv
export PATH=$PYENV_ROOT/bin:$PATH
eval "$(pyenv init -)"

(Rewrite $ HOME to the installation location of pyenv as appropriate) Restart Shell for the settings to take effect.

$ exec $SHELL

1-2. Installing python

Install python from pyenv.

$ pyenv install 2.7.10

Set the installed version.

$ pyenv global 2.7.10
$ pyenv rehash

Verification

$ pyenv versions
* 2.7.10 (set by /hoge/.pyenv/version)

1-3. Django installation and test project creation

Install Django 1.6 from pip

$ pip install django==1.6

Create test project

$ django-admin.py startproject mysite

Server startup

$ cd mysite
$ python manage.py runserver

Go to http: // localhost: 8000 and check if the server is running.

2. Django test project

2-1. Basic usage

Main References Creating your first Django app, part 1 | Django 1.4 Documentation

Editing the configuration file (setting.py)

Change the settings related to DB. By default, sqlite is used, but this time PostgreSQL is used. See Notes on enabling PostgreSQL with Django | Qiita It is assumed that a new user and database are created by installing the postgresql library etc. referring to the above site.

setting.py

DATABASES = {
    'default': {
        # 'ENGINE': 'django.db.backends.sqlite3',
        # 'NAME': os.path.join(BASE_DIR, 'db.sqlite3'),
        'ENGINE': 'django.db.backends.postgresql_psycopg2',
        'NAME': 'mysite',
        'USER': 'djangouser',
        'PASSWORD': 'pass',
        'HOST': '127.0.0.1',
        'PORT': 5432,
    }
}

Creating a table

Create the table used by the application described in INSTALLED_APPS in setting.py by executing the following command.

$ python manage.py syncdb

(The syncdb command looks for the INSTALLED_APPS setting and creates the required table on the database according to the database settings in settings.py.)

Creating an application

$ python manage.py startapp polls

(Polls is the application name)

Creating a model

polls/models.py

from django.db import models

class Poll(models.Model):
    question = models.CharField(max_length=200)
    pub_date = models.DateTimeField('date published')

class Choice(models.Model):
    poll = models.ForeignKey(Poll)
    choice = models.CharField(max_length=200)
    votes = models.IntegerField()

Make your project aware of polls apps

Rewrite the settings to make the project aware of the polls app. Added polls inside ʻINSTALLED_APPS`.

setting.py

INSTALLED_APPS = (
    'django.contrib.auth',
    'django.contrib.contenttypes',
    'django.contrib.sessions',
    'django.contrib.sites',
    'django.contrib.messages',
    'django.contrib.staticfiles',
    # Uncomment the next line to enable the admin:
    # 'django.contrib.admin',
    # Uncomment the next line to enable admin documentation:
    # 'django.contrib.admindocs',
    'polls',
)

Display SQL from the created model

$ python manage.py sql polls
BEGIN;
CREATE TABLE "polls_poll" (
    "id" serial NOT NULL PRIMARY KEY,
    "question" varchar(200) NOT NULL,
    "pub_date" timestamp with time zone NOT NULL
)
;
CREATE TABLE "polls_choice" (
    "id" serial NOT NULL PRIMARY KEY,
    "poll_id" integer NOT NULL REFERENCES "polls_poll" ("id") DEFERRABLE INITIALLY DEFERRED,
    "choice" varchar(200) NOT NULL,
    "votes" integer NOT NULL
);
COMMIT;

Issue SQL statement from model and write to DB

$ python manage.py syncdb

Play Django's API in Python's interactive shell

See Creating your first Django app, part 1 | Django 1.4 Documentation rather than playing with the API.

Launch a python interactive shell.

$ python manage.py shell

(Let's play variously with reference to the above site)

By the way, in the process of playing, polls / models.py was rewritten as follows.

polls/models.py

import datetime
from django.utils import timezone
from django.db import models

class Poll(models.Model):

    question = models.CharField(max_length=200)
    pub_date = models.DateTimeField('date published')

    def __unicode__(self):
        return self.question

    def was_published_recently(self):
        return self.pub_date >= timezone.now() - datetime.timedelta(days=1)


class Choice(models.Model):

    poll = models.ForeignKey(Poll)
    choice = models.CharField(max_length=200)
    votes = models.IntegerField()

    def __unicode__(self):
        return self.choice