django学习（1）编写技巧

从这本书

two-scoops-django-best-practices-1.5

抄过来的。

＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝第一章＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝

风格规范

https://www.python.org/dev/peps/pep-0008/

• “Use 4 spaces per indentation level.”
• “Separate top-level function and class de$nitions with two blank lines.”

• “Method de$nitions inside a class are separated by a single blank line.” 

关于引用

1. Standard library imports

2. Related third-party imports

3. Local application or library speci$c imports 

尽量使用相对路径引用：

from .models import WaffleCone
from .forms import WaffleConeForm

class WaffleConeCreateView(CreateView):
    model = WaffleCone
    form_class = WaffleConeForm

不许用import *

Never Code to the IDE (or Text Editor) 

＝＝＝＝＝＝＝＝＝＝＝＝＝＝第二章＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝

Use the Same Database Locally and in Production 

Use Pip and Virtualenv 

=======================第三章＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝

icratings_project/
    .gitignore

    Makefile
    docs/
    requirements.txt
    icratings/

        manage.py
        media/
        products/
        profiles/
        ratings/
        static/
        templates/
        icratings/

            __init__.py
            settings/
            urls.py
            wsgi.py

大概就是django的项目结构啦。

<repository_root>/
    <django_project_root>/

        <configuration_root>/

Whatever layout is chosen should bedocumented clearly. 

＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝第四章＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝

项目命名和各种app

‘Write programs that do one thing and do it well.’” 

A good, obvious app name makes the project easier tomaintain. 

Use valid, PEP-8-compliant, importable Python package names: short, all-lowercasenames without numbers, dashes, periods, spaces, or special characters. 

When In Doubt, Keep Apps Small 

============================第五章关于配置＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝

• All settings "les need to be version-controlled. 

• Don’t repeat yourself. You should inherit from a base settings  rather than cutting-and-pasting from one to another. 

local_settings.py. you would repeat yourself  and  could go wrong when copying and others.

you should 

Instead of having one settings.py, with this setup you have a settings/ directorycontaining your settings. It will typically contain something like the following 

settings/
      __init__.py

      base.py
      local.py
      staging.py
      test.py
      production.py

and run shell like:

$ django-admin.py shell --settings=twoscoops.settings.local 

$ django-admin.py runserver --settings=twoscoops.settings.local

inheriate

# settings/dev_pydanny.py
from .local import *

Keep Secret Keys Out With Environment Variables 

as platform-as-a-service. 

.bashrc, .bash_profile, or .profile: 

export SOME_SECRET_KEY=1c3-cr3am-15-yummy
export AUDREY_FREEZER_KEY=y34h-r1ght-d0nt-t0uch-my-1c3-cr34m

Handling Missing Secret Key Exceptions 

# settings/base.py
import os

# Normally you should not import ANYTHING from Django directly
# into your settings, but ImproperlyConfigured is an exception.
from django.core.exceptions import ImproperlyConfigured

def get_env_variable(var_name):
    """ Get the environment variable or return exception """
    try:

        return os.environ[var_name]
    except KeyError:

        error_msg = "Set the %s env variable" % var_name
        raise ImproperlyConfigured(error_msg)

SOME_SECRET_KEY = get_env_variable("SOME_SECRET_KEY")

and you would get an exception when you has improbably configured.

Using Multiple Requirements Files 

按以下方式填写需求文件：

requirements/
    _base.txt
    local.txt

    staging.txt
    production.txt

每一个差不多是下面那样：

-r _base.txt # includes the _base.txt requirements file

coverage==3.6
django-discover-runner==0.2.2
django-debug-toolbar==0.9.4

然后按照以下方式安装：

$ pip install -r requirements/local.txt

never hardcode  paths in Django settings .  

you should try something like this:

# At the top of settings/base.py
from os.path import join, abspath, dirname

here = lambda *x: join(abspath(dirname(__file__)), *x)
PROJECT_ROOT = here("..", "..")
root = lambda *x: join(abspath(PROJECT_ROOT), *x)

# Configuring MEDIA_ROOT
MEDIA_ROOT = root('media')

# Configuring STATIC_ROOT
STATIC_ROOT = root('collected_static')

# Additional locations of static files
STATICFILES_DIRS = (

    root('assets'),
)

# Configuring TEMPLATE_DIRS
TEMPLATE_DIRS = (

    root('templates'),
)