如果我只能找到它的位置，我敢肯定这是一个很容易修复的错误。这是来自 Flask 应用程序的错误：
11:58:18 web.1 | ERROR:xxxxxx.core:Exception on / [GET]
11:58:18 web.1 | Traceback (most recent call last):
11:58:18 web.1 | File "/Library/Python/2.7/site-packages/flask/app.py", line 1817, in wsgi_app
11:58:18 web.1 | response = self.full_dispatch_request()
11:58:18 web.1 | File "/Library/Python/2.7/site-packages/flask/app.py", line 1477, in full_dispatch_request
11:58:18 web.1 | rv = self.handle_user_exception(e)
11:58:18 web.1 | File "/Library/Python/2.7/site-packages/flask/app.py", line 1381, in handle_user_exception
11:58:18 web.1 | reraise(exc_type, exc_value, tb)
11:58:18 web.1 | File "/Library/Python/2.7/site-packages/flask/app.py", line 1475, in full_dispatch_request
11:58:18 web.1 | rv = self.dispatch_request()
11:58:18 web.1 | File "/Library/Python/2.7/site-packages/flask/app.py", line 1461, in dispatch_request
11:58:18 web.1 | return self.view_functions[rule.endpoint](**req.view_args)
11:58:18 web.1 | File "xxxxxxx/web.py", line 202, in home
11:58:18 web.1 | d = {'featured': cached_apps.get_featured_front_page(),
11:58:18 web.1 | File "/Library/Python/2.7/site-packages/flask_cache/__init__.py", line 245, in decorated_function
11:58:18 web.1 | rv = f(*args, **kwargs)
11:58:18 web.1 | File "/Users/xxxxxxx/Desktop/PythonProjects/xxxxxx/xxxxxx2/xxxxxxx/cache/apps.py", line 35, in get_featured_front_page
11:58:18 web.1 | results = db.engine.execute(sql)
11:58:18 web.1 | File "/Library/Python/2.7/site-packages/flask_sqlalchemy/__init__.py", line 780, in engine
11:58:18 web.1 | return self.get_engine(self.get_app())
11:58:18 web.1 | File "/Library/Python/2.7/site-packages/flask_sqlalchemy/__init__.py", line 797, in get_engine
11:58:18 web.1 | return connector.get_engine()
11:58:18 web.1 | File "/Library/Python/2.7/site-packages/flask_sqlalchemy/__init__.py", line 470, in get_engine
11:58:18 web.1 | self._sa.apply_driver_hacks(self._app, info, options)
11:58:18 web.1 | File "/Library/Python/2.7/site-packages/flask_sqlalchemy/__init__.py", line 739, in apply_driver_hacks
11:58:18 web.1 | if info.drivername.startswith('mysql'):
11:58:18 web.1 | AttributeError: 'NoneType' object has no attribute 'drivername'
从我在网上找到的内容来看，问题似乎是我可能没有正确连接到数据库。该应用程序在 Heroku 中运行良好，但在我在 localhost 上运行时却不行。
which psql：
/Applications/Postgres.app/Contents/MacOS/bin/psql
which postgres：
/Applications/Postgres.app/Contents/MacOS/bin/postgres
Postgres.app 在 5432 上运行。
我不知道还要检查什么。
如果它应该连接到heroku上的同一个postgres DB，为什么它会在heroku上工作，而不是从localhost？
也许本地主机上的应用程序使用了错误版本的 Postgres？我试过卸载它们（只留下 Postgres.app），但我不确定我的电脑上是否还有任何东西会导致冲突。我将如何检查？我会很感激任何帮助。
编辑：
来自 alembic.ini 文件的更多信息段：
[alembic]
# path to migration scripts
script_location = alembic
# template used to generate migration files
# file_template = %%(rev)s_%%(slug)s
# under Heroku, the line below needs to be inferred from
# the environment
sqlalchemy.url = postgres://xxxxxxxxxx:xxxxxxxxxxxx@xxxxxx.compute-1.amazonaws.com:5432/xxxxxxxxx
# Logging configuration
[loggers]
keys = root,sqlalchemy,alembic
我有一个产生相同错误的简短脚本：我python cli.py db_create
运行
#!/usr/bin/env python
import os
import sys
import optparse
import inspect
import xxxxxxx.model as model
from xxxxxx.core import db
import xxxxx.web as web
from alembic.config import Config
from alembic import command
def setup_alembic_config():
if "DATABASE_URL" not in os.environ:
alembic_cfg = Config("alembic.ini")
else:
dynamic_filename = "alembic-heroku.ini"
with file("alembic.ini.template") as f:
with file(dynamic_filename, "w") as conf:
for line in f.readlines():
if line.startswith("sqlalchemy.url"):
conf.write("sqlalchemy.url = %s\n" %
os.environ['DATABASE_URL'])
else:
conf.write(line)
alembic_cfg = Config(dynamic_filename)
command.stamp(alembic_cfg, "head")
def db_create():
'''Create the db'''
db.create_all()
# then, load the Alembic configuration and generate the
# version table, "stamping" it with the most recent rev:
setup_alembic_config()
# finally, add a minimum set of categories: Volunteer Thinking, Volunteer Sensing, Published and Draft
categories = []
categories.append(model.Category(name="Thinking",
short_name='thinking',
description='Volunteer Thinking apps'))
categories.append(model.Category(name="Volunteer Sensing",
short_name='sensing',
description='Volunteer Sensing apps'))
db.session.add_all(categories)
db.session.commit()
我得到：
Traceback (most recent call last):
File "cli.py", line 111, in <module>
_main(locals())
File "cli.py", line 106, in _main
_methods[method](*args[1:])
File "cli.py", line 33, in db_create
db.create_all()
File "/Library/Python/2.7/site-packages/flask_sqlalchemy/__init__.py", line 856, in create_all
self._execute_for_all_tables(app, bind, 'create_all')
File "/Library/Python/2.7/site-packages/flask_sqlalchemy/__init__.py", line 848, in _execute_for_all_tables
op(bind=self.get_engine(app, bind), tables=tables)
File "/Library/Python/2.7/site-packages/flask_sqlalchemy/__init__.py", line 797, in get_engine
return connector.get_engine()
File "/Library/Python/2.7/site-packages/flask_sqlalchemy/__init__.py", line 470, in get_engine
self._sa.apply_driver_hacks(self._app, info, options)
File "/Library/Python/2.7/site-packages/flask_sqlalchemy/__init__.py", line 739, in apply_driver_hacks
if info.drivername.startswith('mysql'):
AttributeError: 'NoneType' object has no attribute 'drivername'