We have just noticed a python2 bug when using the --sql option.
$ alembic upgrade head --sql > test.sql
Traceback (most recent call last):
File "/home/user/.virtualenvs/alembic2/bin/alembic", line 9, in <module>
load_entry_point('alembic==0.5.0', 'console_scripts', 'alembic')()
File "/home/user/projects/alembic/alembic/config.py", line 269, in main
CommandLine(prog=prog).main(argv=argv)
File "/home/user/projects/alembic/alembic/config.py", line 264, in main
self.run_cmd(cfg, options)
File "/home/user/projects/alembic/alembic/config.py", line 251, in run_cmd
**dict((k, getattr(options, k)) for k in kwarg)
File "/home/user/projects/alembic/alembic/command.py", line 124, in upgrade
script.run_env()
File "/home/user/projects/alembic/alembic/script.py", line 194, in run_env
util.load_python_file(self.dir, 'env.py')
File "/home/user/projects/alembic/alembic/util.py", line 188, in load_python_file
module = imp.load_source(module_id, path, open(path, 'rb'))
File "alembic/env.py", line 74, in <module>
run_migrations_offline()
File "alembic/env.py", line 46, in run_migrations_offline
context.configure(url=url, output_encoding='utf-8')
File "<string>", line 7, in configure
File "/home/user/projects/alembic/alembic/environment.py", line 514, in configure
opts=opts
File "/home/user/projects/alembic/alembic/migration.py", line 144, in configure
return MigrationContext(dialect, connection, opts)
File "/home/user/projects/alembic/alembic/migration.py", line 78, in __init__
opts['output_encoding']
AttributeError: readable
The problem seems to be that using output_encoding in python2 is broken due to the use of io.TextIOWrapper, which does not like to get a file object, which is exactly what python2sys.stdout is. This problem is not displayed in python3 due to the fact of sys.stdout being a io.TextIOWrapper instance.
This behaviour starts at revision ff285f7 which introduces the buffer wrapping for the output_encoding parameter.
The proposed solution is to manually create a writable io.FileIO instance from the stdout file descriptor. This works for both python2 and python3.
We have just noticed a
python2bug when using the--sqloption.$ alembic upgrade head --sql > test.sql Traceback (most recent call last): File "/home/user/.virtualenvs/alembic2/bin/alembic", line 9, in <module> load_entry_point('alembic==0.5.0', 'console_scripts', 'alembic')() File "/home/user/projects/alembic/alembic/config.py", line 269, in main CommandLine(prog=prog).main(argv=argv) File "/home/user/projects/alembic/alembic/config.py", line 264, in main self.run_cmd(cfg, options) File "/home/user/projects/alembic/alembic/config.py", line 251, in run_cmd **dict((k, getattr(options, k)) for k in kwarg) File "/home/user/projects/alembic/alembic/command.py", line 124, in upgrade script.run_env() File "/home/user/projects/alembic/alembic/script.py", line 194, in run_env util.load_python_file(self.dir, 'env.py') File "/home/user/projects/alembic/alembic/util.py", line 188, in load_python_file module = imp.load_source(module_id, path, open(path, 'rb')) File "alembic/env.py", line 74, in <module> run_migrations_offline() File "alembic/env.py", line 46, in run_migrations_offline context.configure(url=url, output_encoding='utf-8') File "<string>", line 7, in configure File "/home/user/projects/alembic/alembic/environment.py", line 514, in configure opts=opts File "/home/user/projects/alembic/alembic/migration.py", line 144, in configure return MigrationContext(dialect, connection, opts) File "/home/user/projects/alembic/alembic/migration.py", line 78, in __init__ opts['output_encoding'] AttributeError: readableThe problem seems to be that using output_encoding in python2 is broken due to the use of
io.TextIOWrapper, which does not like to get afileobject, which is exactly whatpython2sys.stdoutis. This problem is not displayed inpython3due to the fact ofsys.stdoutbeing aio.TextIOWrapperinstance.This behaviour starts at revision ff285f7 which introduces the buffer wrapping for the
output_encodingparameter.The proposed solution is to manually create a writable
io.FileIOinstance from the stdout file descriptor. This works for bothpython2andpython3.