python-dotenv的使用

项目地址：https://github.com/theskumar/python-dotenv

　　首先看一下github上项目的介绍：

　　Reads the key,value pair from .env and adds them to environment variable. 

　　大概意思就是在我们做项目时，我们可以把所有用到的环境变量写到.env文件里，然后以k，v的方式读取作为环境变量。

举个例子Python连接postgresql数据库：

python代码：

#coding:utf-8
import psycopg2 
from dotenv import find_dotenv,load_dotenv
import os
load_dotenv(find_dotenv())
conn=False
conn = psycopg2.connect(os.environ.get('URL'))
if conn:
        print '连接成功！'

.env内容：

URL=postgresql://postgres:[email protected]/postgres

这样我们的项目迁移到不同的环境时只需要更改一下.env的内容就可以了，代码执行时会自动从.env文件里读取所需要的配置信息。

出处：https://www.cnblogs.com/liangping/p/7596265.html

import os
from dotenv import load_dotenv

dotenv_path = os.path.join(os.path.dirname(__file__), '.env')
if os.path.exists(dotenv_path):
    load_dotenv(dotenv_path)

COV = None
if os.environ.get('FLASK_COVERAGE'):
    import coverage
    COV = coverage.coverage(branch=True, include='app/*')
    COV.start()

import os
from dotenv import load_dotenv

dotenv_path = os.path.join(os.path.dirname(__file__), '.env')
if os.path.exists(dotenv_path):
    load_dotenv(dotenv_path)

COV = None
if os.environ.get('FLASK_COVERAGE'):
    import coverage
    COV = coverage.coverage(branch=True, include='app/*')
    COV.start()

import sys
import click
from flask_migrate import Migrate, upgrade
from app import create_app, db
from app.models import User, Follow, Role, Permission, Post, Comment

app = create_app(os.getenv('FLASK_CONFIG') or 'default')
migrate = Migrate(app, db)


@app.shell_context_processor
def make_shell_context():
    return dict(db=db, User=User, Follow=Follow, Role=Role,
                Permission=Permission, Post=Post, Comment=Comment)


@app.cli.command()
@click.option('--coverage/--no-coverage', default=False,
              help='Run tests under code coverage.')
def test(coverage):
    """Run the unit tests."""
    if coverage and not os.environ.get('FLASK_COVERAGE'):
        import subprocess
        os.environ['FLASK_COVERAGE'] = '1'
        sys.exit(subprocess.call(sys.argv))

    import unittest
    tests = unittest.TestLoader().discover('tests')
    unittest.TextTestRunner(verbosity=2).run(tests)
    if COV:
        COV.stop()
        COV.save()
        print('Coverage Summary:')
        COV.report()
        basedir = os.path.abspath(os.path.dirname(__file__))
        covdir = os.path.join(basedir, 'tmp/coverage')
        COV.html_report(directory=covdir)
        print('HTML version: file://%s/index.html' % covdir)
        COV.erase()


@app.cli.command()
@click.option('--length', default=25,
              help='Number of functions to include in the profiler report.')
@click.option('--profile-dir', default=None,
              help='Directory where profiler data files are saved.')
def profile(length, profile_dir):
    """Start the application under the code profiler."""
    from werkzeug.contrib.profiler import ProfilerMiddleware
    app.wsgi_app = ProfilerMiddleware(app.wsgi_app, restrictions=[length],
                                      profile_dir=profile_dir)
    app.run()


@app.cli.command()
def deploy():
    """Run deployment tasks."""
    # migrate database to latest revision
    upgrade()

    # create or update user roles
    Role.insert_roles()

    # ensure all users are following themselves
    User.add_self_follows()