【Youtobe trydjango】Django2.2教程和React实战系列二【settings配置文件】

1. Django项目初始化过程
2. 全貌
3. 详细解释
4. 增加其他配置

1. Django项目初始化过程

当我们python.exe manage.py启动django项目的时候，程序究竟做了什么呢？

来看一下E:\randolph\trydjango\src\trydjango\manage.py文件：

#!/usr/bin/env python
"""Django's command-line utility for administrative tasks."""
import os
import sysdef main():os.environ.setdefault('DJANGO_SETTINGS_MODULE', 'trydjango.settings')try:from django.core.management import execute_from_command_lineexcept ImportError as exc:raise ImportError("Couldn't import Django. Are you sure it's installed and ""available on your PYTHONPATH environment variable? Did you ""forget to activate a virtual environment?") from excprint(sys.argv)execute_from_command_line(sys.argv)if __name__ == '__main__':main()

从main()函数入口，os.environ.setdefault('DJANGO_SETTINGS_MODULE', 'trydjango.settings')环境变量字典中添加一个叫做DJANGO_SETTINGS_MODULE的变量，内容是trydjango.settings，目的是将项目的配置文件送入环境变量中。

from django.core.management import execute_from_command_line然后导入execute_from_command_line函数，执行语句execute_from_command_line(sys.argv)
sys.argv参数是['E:\\randolph\\trydjango\\src\\trydjango\\manage.py', 'runserver', '--noreload']，
execute_from_command_line函数做了什么事情呢？
如下，实例化一个ManagementUtility类为utility对象，将sys.argv送入形参argv，然后utility对象调用内部方法execute()

ManagementUtility类封装django-admin和manage.py实用程序的逻辑Encapsulate the logic of the django-admin and manage.py utilities.

def execute_from_command_line(argv=None):"""Run a ManagementUtility."""utility = ManagementUtility(argv)utility.execute()

内部方法execute()做了什么呢？
Given the command-line arguments, figure out which subcommand is being run, create a parser appropriate to that command, and run it.
给定命令行参数，找出正在运行的子命令，创建适合该命令的解析器，然后运行它。
在各种参数获取和处理后可以看到运行了这样一句django.setup()
很明显，启动django项目命令，不过我没点进去，先到此为止吧。

2. 全貌

Django框架的全局配置文件的位置在E:\randolph\trydjango\src\trydjango\trydjango\settings；

当创建django项目的时候，会自动根据项目名初始化这样一个django文件，在上面启动django项目的时候会将配置文件打入环境变量中即可取用。

"""
Django settings for trydjango project.Generated by 'django-admin startproject' using Django 2.2.14.For more information on this file, see
https://docs.djangoproject.com/en/2.2/topics/settings/For the full list of settings and their values, see
https://docs.djangoproject.com/en/2.2/ref/settings/
"""import os# Build paths inside the project like this: os.path.join(BASE_DIR, ...)
BASE_DIR = os.path.dirname(os.path.dirname(os.path.abspath(__file__)))
# E:\randolph\trydjango\src\trydjango# Quick-start development settings - unsuitable for production
# See https://docs.djangoproject.com/en/2.2/howto/deployment/checklist/# SECURITY WARNING: keep the secret key used in production secret!
SECRET_KEY = 'hx^hzx@-l!r$kpj2av(_@o2vk8=q#(a2+=ry(2f^w3f53**zoe'# SECURITY WARNING: don't run with debug turned on in production!
DEBUG = TrueALLOWED_HOSTS = []# Application definitionINSTALLED_APPS = ['django.contrib.admin','django.contrib.auth','django.contrib.contenttypes','django.contrib.sessions','django.contrib.messages','django.contrib.staticfiles',
]MIDDLEWARE = ['django.middleware.security.SecurityMiddleware','django.contrib.sessions.middleware.SessionMiddleware','django.middleware.common.CommonMiddleware','django.middleware.csrf.CsrfViewMiddleware','django.contrib.auth.middleware.AuthenticationMiddleware','django.contrib.messages.middleware.MessageMiddleware','django.middleware.clickjacking.XFrameOptionsMiddleware',
]ROOT_URLCONF = 'trydjango.urls'TEMPLATES = [{'BACKEND': 'django.template.backends.django.DjangoTemplates','DIRS': [],'APP_DIRS': True,'OPTIONS': {'context_processors': ['django.template.context_processors.debug','django.template.context_processors.request','django.contrib.auth.context_processors.auth','django.contrib.messages.context_processors.messages',],},},
]WSGI_APPLICATION = 'trydjango.wsgi.application'# Database
# https://docs.djangoproject.com/en/2.2/ref/settings/#databasesDATABASES = {'default': {'ENGINE': 'django.db.backends.sqlite3','NAME': os.path.join(BASE_DIR, 'db.sqlite3'),}
}# Password validation
# https://docs.djangoproject.com/en/2.2/ref/settings/#auth-password-validatorsAUTH_PASSWORD_VALIDATORS = [{'NAME': 'django.contrib.auth.password_validation.UserAttributeSimilarityValidator',},{'NAME': 'django.contrib.auth.password_validation.MinimumLengthValidator',},{'NAME': 'django.contrib.auth.password_validation.CommonPasswordValidator',},{'NAME': 'django.contrib.auth.password_validation.NumericPasswordValidator',},
]# Internationalization
# https://docs.djangoproject.com/en/2.2/topics/i18n/LANGUAGE_CODE = 'en-us'TIME_ZONE = 'UTC'USE_I18N = TrueUSE_L10N = TrueUSE_TZ = True# Static files (CSS, JavaScript, Images)
# https://docs.djangoproject.com/en/2.2/howto/static-files/STATIC_URL = '/static/'

3. 详细解释

BASE_DIR
常用的拼接方式，将项目的根目录的绝对路径拼接出来：
E:\randolph\trydjango\src\trydjango
SECRET_KEY
安全key，长度固定，里面字符串随意修改下
DEBUG
是否debug模式
ALLOWED_HOSTS
INSTALLED_APPS
app路径，新建的应用都要在这里添加，例如： ‘app1’
MIDDLEWARE
中间件
ROOT_URLCONF
TEMPLATES
WSGI_APPLICATION
wsgi配置
DATABASES
如果使用django的默认sqlite3数据库则不需要改，使用mysql例：
需要安装并引入pymysql库

DATABASES = {'default': {  'ENGINE': 'django.db.backends.mysql','NAME': 'blog', #你的数据库名称 数据库需要自己提前建好'USER': 'root', #你的数据库用户名'PASSWORD': '', #你的数据库密码'HOST': '', #你的数据库主机，留空默认为localhost'PORT': '3306', #你的数据库端口}
}

AUTH_PASSWORD_VALIDATORS
LANGUAGE_CODE
语言
TIME_ZONE
时区
USE_I18N
国家化
USE_L10N
USE_TZ
STATIC_URL
静态文件目录，需要添加一行

STATICFILES_DIRS=[os.path.join(BASE_DIR, "static"),       # 具体路径
]

4. 增加其他配置

待定