sqlalchemy.exc.ArgumentError：无法解析字符串中的rfc1738 URL

Question

我正在学习flask web微框架，并在初始化数据库后flask db init运行flask db migrate，将模型类迁移到数据库，但出现错误。在Windows 10我的工作，该数据库为MySQL和扩展安装是flask-migrate，flask-sqlalchemy，flask-login。

(env) ? flask db migrate
Traceback (most recent call last):
  File "c:\python36\Lib\runpy.py", line 193, in _run_module_as_main
    "__main__", mod_spec)
  File "c:\python36\Lib\runpy.py", line 85, in _run_code
    exec(code, run_globals)
  File "C:\Users\aka\Dev\dream-team\env\Scripts\flask.exe\__main__.py", line 9, in <module>
  File "c:\users\aka\dev\dream-team\env\lib\site-packages\flask\cli.py", line 513, in main
    cli.main(args=args, prog_name=name)
  File "c:\users\aka\dev\dream-team\env\lib\site-packages\flask\cli.py", line 380, in main
    return AppGroup.main(self, *args, **kwargs)
  File "c:\users\aka\dev\dream-team\env\lib\site-packages\click\core.py", line 697, in main
    rv = self.invoke(ctx)
  File "c:\users\aka\dev\dream-team\env\lib\site-packages\click\core.py", line 1066, in invoke
    return _process_result(sub_ctx.command.invoke(sub_ctx))
  File "c:\users\aka\dev\dream-team\env\lib\site-packages\click\core.py", line 1066, in invoke
    return _process_result(sub_ctx.command.invoke(sub_ctx))
  File "c:\users\aka\dev\dream-team\env\lib\site-packages\click\core.py", line 895, in invoke
    return ctx.invoke(self.callback, **ctx.params)
  File "c:\users\aka\dev\dream-team\env\lib\site-packages\click\core.py", line 535, in invoke
    return callback(*args, **kwargs)
  File "c:\users\aka\dev\dream-team\env\lib\site-packages\click\decorators.py", line 17, in new_func
    return f(get_current_context(), *args, **kwargs)
  File "c:\users\aka\dev\dream-team\env\lib\site-packages\flask\cli.py", line 257, in decorator
    return __ctx.invoke(f, *args, **kwargs)
  File "c:\users\aka\dev\dream-team\env\lib\site-packages\click\core.py", line 535, in invoke
    return callback(*args, **kwargs)
  File "c:\users\aka\dev\dream-team\env\lib\site-packages\flask_migrate\cli.py", line 90, in migrate
    rev_id, x_arg)
  File "c:\users\aka\dev\dream-team\env\lib\site-packages\flask_migrate\__init__.py", line 197, in migrate
    version_path=version_path, rev_id=rev_id)
  File "c:\users\aka\dev\dream-team\env\lib\site-packages\alembic\command.py", line 176, in revision
    script_directory.run_env()
  File "c:\users\aka\dev\dream-team\env\lib\site-packages\alembic\script\base.py", line 427, in run_env
    util.load_python_file(self.dir, 'env.py')
  File "c:\users\aka\dev\dream-team\env\lib\site-packages\alembic\util\pyfiles.py", line 81, in load_python_file
    module = load_module_py(module_id, path)
  File "c:\users\aka\dev\dream-team\env\lib\site-packages\alembic\util\compat.py", line 83, in load_module_py
    spec.loader.exec_module(module)
  File "<frozen importlib._bootstrap_external>", line 678, in exec_module
  File "<frozen importlib._bootstrap>", line 219, in _call_with_frames_removed
  File "migrations\env.py", line 87, in <module>
    run_migrations_online()
  File "migrations\env.py", line 70, in run_migrations_online
    poolclass=pool.NullPool)
  File "c:\users\aka\dev\dream-team\env\lib\site-packages\sqlalchemy\engine\__init__.py", line 465, in engine_from_config
    return create_engine(url, **options)
  File "c:\users\aka\dev\dream-team\env\lib\site-packages\sqlalchemy\engine\__init__.py", line 424, in create_engine
    return strategy.create(*args, **kwargs)
  File "c:\users\aka\dev\dream-team\env\lib\site-packages\sqlalchemy\engine\strategies.py", line 50, in create
    u = url.make_url(name_or_url)
  File "c:\users\aka\dev\dream-team\env\lib\site-packages\sqlalchemy\engine\url.py", line 211, in make_url
    return _parse_rfc1738_args(name_or_url)
  File "c:\users\aka\dev\dream-team\env\lib\site-packages\sqlalchemy\engine\url.py", line 270, in _parse_rfc1738_args
    "Could not parse rfc1738 URL from string '%s'" % name)
sqlalchemy.exc.ArgumentError: Could not parse rfc1738 URL from string 'mysql/dt_admin:dt2016@localhost/dreamteam_db'

Answer 1

您在连接字符串中没有使用有效的URL。

查看有关如何构造MySQL连接URL的文档：http : //docs.sqlalchemy.org/en/latest/dialects/mysql.html。

根据使用的MySQL驱动程序，连接URL是不同的。例如，如果使用pymysql，则URL应为：

mysql+pymysql://<username>:<password>@<host>/<dbname>[?<options>]

Answer 2

我会忘记输入端口的端口号，这是 URL 连接字符串：

`SQLALCHEMY_DATABASE_URI = 'mysql://dt_admin:dt2016@localhost:3308/dreamteam_db'

现在可以用了，谢谢

Answer 3

只需删除引号

我是这样使用的：

sql_alchemy_conn = 'postgresql://user:password@host:port/db'

这有效：

sql_alchemy_conn = postgresql://user:password@host:port/db