sqlalchemy.exc.OperationalError: (psycopg2.OperationalError) fe_sendauth: 未提供密码答案

【问题标题】：sqlalchemy.exc.OperationalError: (psycopg2.OperationalError) fe_sendauth: no password suppliedsqlalchemy.exc.OperationalError: (psycopg2.OperationalError) fe_sendauth: 未提供密码
【发布时间】：2020-04-04 23:14:12
【问题描述】：

我正在尝试运行这个简单的烧瓶应用程序，但在尝试运行烧瓶应用程序时，我一直在终端中收到此错误 FLASK_APP=app.py flask run 我不断收到此错误： sqlalchemy.exc.OperationalError: (psycopg2.OperationalError) fe_sendauth: no password supplied

这是我的应用程序：

from flask import Flask
from flask_sqlalchemy import SQLAlchemy
app = Flask(__name__)
app.config['SQLALCHEMY_DATABASE_URI'] = 'postgresql://postgres@localhost:5432/testdb'
db = SQLAlchemy(app)
class Person(db.Model):
  __tablename__ = 'persons'
  id = db.Column(db.Integer, primary_key=True)
  name = db.Column(db.String(), nullable=False)
db.create_all()
@app.route('/')
def index():
    return 'Hello World!'

只是为了澄清我已经安装了 psycopg2、flask-SQLAlchemy 和所有依赖项默认情况下没有用户 postgres 的密码，我没有更改它，我可以作为 postgres 登录到数据库使用 psql 没有密码没有任何问题。

完整的错误输出：

FLASK_APP=app.py flask run
 * Serving Flask app "app.py"
 * Environment: production
   WARNING: This is a development server. Do not use it in a production deployment.
   Use a production WSGI server instead.
 * Debug mode: off
/usr/lib/python3/dist-packages/flask_sqlalchemy/__init__.py:800: UserWarning: SQLALCHEMY_TRACK_MODIFICATIONS adds significant overhead and will be disabled by default in the future.  Set it to True to suppress this warning.
  warnings.warn('SQLALCHEMY_TRACK_MODIFICATIONS adds significant overhead and will be disabled by default in the future.  Set it to True to suppress this warning.')
Traceback (most recent call last):
  File "/usr/lib/python3/dist-packages/sqlalchemy/pool.py", line 1122, in _do_get
    return self._pool.get(wait, self._timeout)
  File "/usr/lib/python3/dist-packages/sqlalchemy/util/queue.py", line 145, in get
    raise Empty
sqlalchemy.util.queue.Empty
During handling of the above exception, another exception occurred:
Traceback (most recent call last):
  File "/usr/lib/python3/dist-packages/sqlalchemy/engine/base.py", line 2147, in _wrap_pool_connect
    return fn()
  File "/usr/lib/python3/dist-packages/sqlalchemy/pool.py", line 387, in connect
    return _ConnectionFairy._checkout(self)
  File "/usr/lib/python3/dist-packages/sqlalchemy/pool.py", line 766, in _checkout
    fairy = _ConnectionRecord.checkout(pool)
  File "/usr/lib/python3/dist-packages/sqlalchemy/pool.py", line 516, in checkout
    rec = pool._do_get()
  File "/usr/lib/python3/dist-packages/sqlalchemy/pool.py", line 1138, in _do_get
    self._dec_overflow()
  File "/usr/lib/python3/dist-packages/sqlalchemy/util/langhelpers.py", line 66, in __exit__
    compat.reraise(exc_type, exc_value, exc_tb)
  File "/usr/lib/python3/dist-packages/sqlalchemy/util/compat.py", line 187, in reraise
    raise value
  File "/usr/lib/python3/dist-packages/sqlalchemy/pool.py", line 1135, in _do_get
    return self._create_connection()
  File "/usr/lib/python3/dist-packages/sqlalchemy/pool.py", line 333, in _create_connection
    return _ConnectionRecord(self)
  File "/usr/lib/python3/dist-packages/sqlalchemy/pool.py", line 461, in __init__
    self.__connect(first_connect_check=True)
  File "/usr/lib/python3/dist-packages/sqlalchemy/pool.py", line 651, in __connect
    connection = pool._invoke_creator(self)
  File "/usr/lib/python3/dist-packages/sqlalchemy/engine/strategies.py", line 105, in connect
    return dialect.connect(*cargs, **cparams)
  File "/usr/lib/python3/dist-packages/sqlalchemy/engine/default.py", line 393, in connect
    return self.dbapi.connect(*cargs, **cparams)
  File "/home/aa/.local/lib/python3.6/site-packages/psycopg2/__init__.py", line 126, in connect
    conn = _connect(dsn, connection_factory=connection_factory, **kwasync)
psycopg2.OperationalError: fe_sendauth: no password supplied
The above exception was the direct cause of the following exception:
Traceback (most recent call last):
  File "/home/aa/.local/bin/flask", line 11, in <module>
    sys.exit(main())
  File "/home/aa/.local/lib/python3.6/site-packages/flask/cli.py", line 967, in main
    cli.main(args=sys.argv[1:], prog_name="python -m flask" if as_module else None)
  File "/home/aa/.local/lib/python3.6/site-packages/flask/cli.py", line 586, in main
    return super(FlaskGroup, self).main(*args, **kwargs)
  File "/home/aa/.local/lib/python3.6/site-packages/click/core.py", line 782, in main
    rv = self.invoke(ctx)
  File "/home/aa/.local/lib/python3.6/site-packages/click/core.py", line 1259, in invoke
    return _process_result(sub_ctx.command.invoke(sub_ctx))
  File "/home/aa/.local/lib/python3.6/site-packages/click/core.py", line 1066, in invoke
    return ctx.invoke(self.callback, **ctx.params)
  File "/home/aa/.local/lib/python3.6/site-packages/click/core.py", line 610, in invoke
    return callback(*args, **kwargs)
  File "/home/aa/.local/lib/python3.6/site-packages/click/decorators.py", line 73, in new_func
    return ctx.invoke(f, obj, *args, **kwargs)
  File "/home/aa/.local/lib/python3.6/site-packages/click/core.py", line 610, in invoke
    return callback(*args, **kwargs)
  File "/home/aa/.local/lib/python3.6/site-packages/flask/cli.py", line 848, in run_command
    app = DispatchingApp(info.load_app, use_eager_loading=eager_loading)
  File "/home/aa/.local/lib/python3.6/site-packages/flask/cli.py", line 305, in __init__
    self._load_unlocked()
  File "/home/aa/.local/lib/python3.6/site-packages/flask/cli.py", line 330, in _load_unlocked
    self._app = rv = self.loader()
  File "/home/aa/.local/lib/python3.6/site-packages/flask/cli.py", line 388, in load_app
    app = locate_app(self, import_name, name)
  File "/home/aa/.local/lib/python3.6/site-packages/flask/cli.py", line 240, in locate_app
    __import__(module_name)
  File "/home/aa/Desktop/Udacity - FullStackND 2020/FullStackND2020/Practice Projects/flask hello world app/app.py", line 18, in <module>
    db.create_all()
  File "/usr/lib/python3/dist-packages/flask_sqlalchemy/__init__.py", line 972, in create_all
    self._execute_for_all_tables(app, bind, 'create_all')
  File "/usr/lib/python3/dist-packages/flask_sqlalchemy/__init__.py", line 964, in _execute_for_all_tables
    op(bind=self.get_engine(app, bind), **extra)
  File "/usr/lib/python3/dist-packages/sqlalchemy/sql/schema.py", line 3934, in create_all
    tables=tables)
  File "/usr/lib/python3/dist-packages/sqlalchemy/engine/base.py", line 1928, in _run_visitor
    with self._optional_conn_ctx_manager(connection) as conn:
  File "/usr/lib/python3.6/contextlib.py", line 81, in __enter__
    return next(self.gen)
  File "/usr/lib/python3/dist-packages/sqlalchemy/engine/base.py", line 1921, in _optional_conn_ctx_manager
    with self.contextual_connect() as conn:
  File "/usr/lib/python3/dist-packages/sqlalchemy/engine/base.py", line 2112, in contextual_connect
    self._wrap_pool_connect(self.pool.connect, None),
  File "/usr/lib/python3/dist-packages/sqlalchemy/engine/base.py", line 2151, in _wrap_pool_connect
    e, dialect, self)
  File "/usr/lib/python3/dist-packages/sqlalchemy/engine/base.py", line 1465, in _handle_dbapi_exception_noconnection
    exc_info
  File "/usr/lib/python3/dist-packages/sqlalchemy/util/compat.py", line 203, in raise_from_cause
    reraise(type(exception), exception, tb=exc_tb, cause=cause)
  File "/usr/lib/python3/dist-packages/sqlalchemy/util/compat.py", line 186, in reraise
    raise value.with_traceback(tb)
  File "/usr/lib/python3/dist-packages/sqlalchemy/engine/base.py", line 2147, in _wrap_pool_connect
    return fn()
  File "/usr/lib/python3/dist-packages/sqlalchemy/pool.py", line 387, in connect
    return _ConnectionFairy._checkout(self)
  File "/usr/lib/python3/dist-packages/sqlalchemy/pool.py", line 766, in _checkout
    fairy = _ConnectionRecord.checkout(pool)
  File "/usr/lib/python3/dist-packages/sqlalchemy/pool.py", line 516, in checkout
    rec = pool._do_get()
  File "/usr/lib/python3/dist-packages/sqlalchemy/pool.py", line 1138, in _do_get
    self._dec_overflow()
  File "/usr/lib/python3/dist-packages/sqlalchemy/util/langhelpers.py", line 66, in __exit__
    compat.reraise(exc_type, exc_value, exc_tb)
  File "/usr/lib/python3/dist-packages/sqlalchemy/util/compat.py", line 187, in reraise
    raise value
  File "/usr/lib/python3/dist-packages/sqlalchemy/pool.py", line 1135, in _do_get
    return self._create_connection()
  File "/usr/lib/python3/dist-packages/sqlalchemy/pool.py", line 333, in _create_connection
    return _ConnectionRecord(self)
  File "/usr/lib/python3/dist-packages/sqlalchemy/pool.py", line 461, in __init__
    self.__connect(first_connect_check=True)
  File "/usr/lib/python3/dist-packages/sqlalchemy/pool.py", line 651, in __connect
    connection = pool._invoke_creator(self)
  File "/usr/lib/python3/dist-packages/sqlalchemy/engine/strategies.py", line 105, in connect
    return dialect.connect(*cargs, **cparams)
  File "/usr/lib/python3/dist-packages/sqlalchemy/engine/default.py", line 393, in connect
    return self.dbapi.connect(*cargs, **cparams)
  File "/home/aa/.local/lib/python3.6/site-packages/psycopg2/__init__.py", line 126, in connect
    conn = _connect(dsn, connection_factory=connection_factory, **kwasync)
sqlalchemy.exc.OperationalError: (psycopg2.OperationalError) fe_sendauth: no password supplied

【问题讨论】：

标签： postgresql flask sqlalchemy flask-sqlalchemy

【解决方案1】：

除了设置密码，您还可以通过以下方式无需密码登录：

启用信任认证，例如echo "local all all trust" | sudo tee -a /etc/postgresql/10/main/pg_hba.conf
使用与本地用户名相同的用户名创建具有登录访问权限的角色，例如如果whoami 返回myname，则sudo -u postgres psql -c "CREATE ROLE myname WITH LOGIN"
使用sqlalchemy的postgresql unix域连接代替tcp（ref），例如"postgres+psycopg2://myname@/mydb"

注意这需要安装pip3 install psycopg2-binary

【讨论】：

【解决方案2】：

显然你需要密码才能从 SQLAlchemy 连接到数据库，我可以通过简单地创建密码或添加带有密码的新用户来解决这个问题。

如果有不同的解决方法/解决方案，请告诉我

【讨论】：