sqlalchemy.exc.ArgumentError: Could not parse rfc1738 URL from string

Question

I'm learning flask web microframework and after initialization of my database I run flask db init I run flask db migrate, to migrate my models classes to the database and i got an error. I work on Windows 10, the database is MySQL, and extensions install are flask-migrate, flask-sqlalchemy, flask-login.

(env) λ 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'

might be helpful to post your model definitions. I assume the problem is in there! — Daniel da Rocha
– Daniel da Rocha, Commented Apr 12, 2018 at 2:42

Miguel Grinberg · Accepted Answer · 2018-04-12 15:46:35Z

21

You are not using a valid URL in the connection string.

Review the documentation on how the MySQL connection URLs need to be structured: http://docs.sqlalchemy.org/en/latest/dialects/mysql.html.

Depending on the MySQL driver that you use the connection URL is different. For example, if you use pymysql, your URL should be:

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

answered Apr 12, 2018 at 15:46

Miguel Grinberg

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5 Comments

sylvan kadjo Over a year ago

i'd forget the port number to enter the port, this is the URL connection string: it work now, thank you

discipleartem Over a year ago

it is important NOT to make spaces in the ' '. SQLALCHEMY_DATABASE_URI = 'mysql+mysqlconnector://<username>:<password>@<host>/<dbname>[?<options>]'

Alex Deft Over a year ago

@Miguel I am literally using URL.create from engine module to avoid any errors in writing that URL, yet, I'm getting this error.

Miguel Grinberg Over a year ago

@AlexDeft Think about it. There is only two possibilities. Option a) you are passing a bad URL and SQLAlchemy rightfully errors and b) you are passing a correct URL and SQLAlchemy has a bug that makes it report a false error. Which one do you think it is? If you think it is b), then file a bug with SQLAlchemy. If you think it is a) then I have no way to help, because you are not showing your work.

Alex Deft Over a year ago

@Miguel I restarted the machine and it worked :/

sylvan kadjo · Accepted Answer · 2018-04-13 15:53:02Z

8

i'd forget the port number to enter the port, this is the URL connection string:

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

it work now, thanks

answered Apr 13, 2018 at 15:53

sylvan kadjo

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Comments

Claudio Shigueo Watanabe · Accepted Answer · 2022-04-28 10:44:52Z

6

just had to remove the quotes

I was using like that:

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

And this worked:

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

answered Apr 28, 2022 at 10:44

Claudio Shigueo Watanabe

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Comments

officialrahulmandal · Accepted Answer · 2020-11-29 02:15:39Z

3

URL in the connection string is not valid.

you can check the documentation on how the MySQL connection URLs need to be structured here : http://docs.sqlalchemy.org/en/latest/dialects/mysql.html.

Example syntax for postgresql with psycopg2 driver it look like this :-

sql_alchemy_conn = postgresql+psycopg2://ubuntu@localhost:5432/airflow

answered Nov 29, 2020 at 2:15

officialrahulmandal

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Comments

Ahmed Damasy · Accepted Answer · 2020-11-25 00:27:50Z

2

make sure that there is no space or newline in the URI string

answered Nov 25, 2020 at 0:27

Ahmed Damasy

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Comments

DINA TAKLIT · Accepted Answer · 2022-07-08 20:49:35Z

For me I got this error once I was trying to fix this issue

 raise TypeError("option values must be strings")
TypeError: option values must be strings

so I tried to stringify the url like so

config.set_main_option(
    "sqlalchemy.url", f'{os.environ.get("DATABASE_URL")}')

After that I got new error because os.environ.get() does not return the Environment Value in windows without exporting the value, here is the error I got

sqlalchemy.exc.ArgumentError: Could not parse rfc1738 URL from string 'None'

So I should either export the value than get it with os.environ.get() or use a config file and get it like so:

config.set_main_option(
    "sqlalchemy.url", settings.database_url.replace("postgres://", "postgresql+asyncpg://", 1))

A detail about how to get env vars using config file you can find it on this answer os.environ.get() does not return the Environment Value in windows?

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