best practice for creating new tables
I've been working with sqlalchemy/alembic for several years now, but just recently stumbled on an important issue. Here is how I use to work: 1. Issue Base.metadata.create_all(engine) to make sure that missing tables are created 2. check the current revision by issuing context.get_current_revision() 3. running command.stamp or command.upgrade if the revision is the latest or not respectively This worked well up until the point where I needed to change a table name since create_all created a new table and then upgrade just failed. Issuing create_all after the upgrade isn't an option also since changes to missing tables will also fail. What is the proper way of doing this? Before I run to add a create_table in each revision I had, I wanted to check if there's a better way of handling things. What's your opinion? If table rename is the only problem with my first take, is there a way to exclude a table from create_all using a 'filter' function? (that way, I could add a property to the model stating it's previous name as check for that property in the 'filter' function... -- You received this message because you are subscribed to the Google Groups "sqlalchemy-alembic" group. To unsubscribe from this group and stop receiving emails from it, send an email to sqlalchemy-alembic+unsubscr...@googlegroups.com. For more options, visit https://groups.google.com/d/optout.
Re: [sqlalchemy] Error with SQL Server and utf-8 encoding
On 9/1/15 11:28 AM, Massi wrote:
Hi everyone,
I'm trying to manage read and write operations of utf-8 unicode
strings with SQL Server (sqlalchemy 0.9.10), but I'm having some
problems. I correctly write the strings to the database, but when I
read them back and try to convert to unicode I get the following error:
Traceback (most recent call last):
File "C:\Users\Impara 01\Desktop\t.py", line 18, in
print unicode(row[0], "utf-8")
UnicodeDecodeError: 'utf8' codec can't decode byte 0xe0 in position 0:
invalid continuation byte
Process terminated with an exit code of 1
Here is a sample code showing the problem:
# -*- coding: utf-8 -*-
import sqlalchemy
from sqlalchemy import select, create_engine, MetaData, Table, Column
import datetime
engine =
create_engine('mssql+pyodbc://MYHOST\SQLEXPRESS/user?trusted_connection=True=utf8')
metadata = MetaData(engine)
t = Table('test', metadata,
Column('unicode', sqlalchemy.dialects.mssql.VARCHAR())
)
t.create()
s = "àèìòù"
s = unicode(s, "utf-8")
t.insert().values(unicode=s).execute()
res = select([t.c.unicode]).execute().fetchall()
for i, row in enumerate(res):
print unicode(row[0], "utf-8")
Can anyone point me out what I'm doing wrong?
pyodbc and SQL Server are very particular about unicode. In this case
it seems like you are passing a Python unicode literal into Pyodbc, and
assuming Pyodbc knows how to handle that, but then on the reception side
you're assuming that you're getting a bytestring back, and not again a
Python Unicode object.
to do a unicode round trip, use the SQLAlchemy Unicode type, and deal
only with Python unicode literals in your script:
t = Table( Column('x', sqlalchemy.Unicode()))
s = u'àèìòù'
t.insert().values(unicode=s) ...
for row in res:
print row[0]
SQLAlchemy will make sure that the value is passed to pyodbc in the
expected format, in this case it is likely encoding to utf-8 on the way
in and decoding from utf-8 on the way out.
Thanks in advance!
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[sqlalchemy] Error with SQL Server and utf-8 encoding
Hi everyone,
I'm trying to manage read and write operations of utf-8 unicode strings
with SQL Server (sqlalchemy 0.9.10), but I'm having some problems. I
correctly write the strings to the database, but when I read them back and
try to convert to unicode I get the following error:
Traceback (most recent call last):
File "C:\Users\Impara 01\Desktop\t.py", line 18, in
print unicode(row[0], "utf-8")
UnicodeDecodeError: 'utf8' codec can't decode byte 0xe0 in position 0:
invalid continuation byte
Process terminated with an exit code of 1
Here is a sample code showing the problem:
# -*- coding: utf-8 -*-
import sqlalchemy
from sqlalchemy import select, create_engine, MetaData, Table, Column
import datetime
engine =
create_engine('mssql+pyodbc://MYHOST\SQLEXPRESS/user?trusted_connection=True=utf8')
metadata = MetaData(engine)
t = Table('test', metadata,
Column('unicode', sqlalchemy.dialects.mssql.VARCHAR())
)
t.create()
s = "àèìòù"
s = unicode(s, "utf-8")
t.insert().values(unicode=s).execute()
res = select([t.c.unicode]).execute().fetchall()
for i, row in enumerate(res):
print unicode(row[0], "utf-8")
Can anyone point me out what I'm doing wrong?
Thanks in advance!
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