AttributeError: viewonly

[Zheng Li]

I encountered the following error message when trying "otree devserver". This never happened, and I'm not sure what exactly I did to cause it.

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Traceback (most recent call last):

  File "C:\Program Files\Python39\Scripts\otree-script.py", line 33, in <module>

    sys.exit(load_entry_point('otree==5.1.10', 'console_scripts', 'otree')())

  File "c:\program files\python39\lib\site-packages\otree\main.py", line 106, in execute_from_command_line

    setup()

  File "c:\program files\python39\lib\site-packages\otree\main.py", line 140, in setup

    init_orm()

  File "c:\program files\python39\lib\site-packages\otree\database.py", line 307, in init_orm

    configure_mappers()

  File "C:\Users\user\AppData\Roaming\Python\Python39\site-packages\sqlalchemy\orm\mapper.py", line 3299, in configure_mappers

    mapper._post_configure_properties()

  File "C:\Users\user\AppData\Roaming\Python\Python39\site-packages\sqlalchemy\orm\mapper.py", line 1965, in _post_configure_properties

    prop.init()

  File "C:\Users\user\AppData\Roaming\Python\Python39\site-packages\sqlalchemy\orm\interfaces.py", line 197, in init

    self.do_init()

  File "C:\Users\user\AppData\Roaming\Python\Python39\site-packages\sqlalchemy\orm\relationships.py", line 2081, in do_init

    self._generate_backref()

  File "C:\Users\user\AppData\Roaming\Python\Python39\site-packages\sqlalchemy\orm\relationships.py", line 2395, in _generate_backref

    self._add_reverse_property(self.back_populates)

  File "C:\Users\user\AppData\Roaming\Python\Python39\site-packages\sqlalchemy\orm\relationships.py", line 2011, in _add_reverse_property

    self._check_sync_backref(other, self)

  File "C:\Users\user\AppData\Roaming\Python\Python39\site-packages\sqlalchemy\orm\relationships.py", line 1988, in _check_sync_backref

    if rel_a.viewonly and rel_b.sync_backref:

  File "C:\Users\user\AppData\Roaming\Python\Python39\site-packages\sqlalchemy\util\langhelpers.py", line 987, in __getattr__

    return self._fallback_getattr(key)

  File "C:\Users\user\AppData\Roaming\Python\Python39\site-packages\sqlalchemy\util\langhelpers.py", line 961, in _fallback_getattr

    raise AttributeError(key)

AttributeError: viewonly

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[Zheng Li]

Is this because library " sqlalchemy"? I recall that I recently changed the version of  sqlalchemy...

[Chris @ oTree]

It could be sqlalchemy. You should use the same version of sqlalchemy that otree installs automatically. 

Sent from my phone

On May 27, 2021, at 2:18 AM, Zheng Li <axia...@gmail.com> wrote:

Is this because library " sqlalchemy"? I recall that I recently changed the version of  sqlalchemy...

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[Zheng Li]

Thanks Chris! Weird enough, another otree project of mine works just fine... I really wonder what was causing this - I haven't figured out a way to fix this. 

What is the default sqlalchemy version for otree?

[Chris @ oTree]

Try reinstalling oTree and it should straighten things out.