On Apr 12, 2012, at 10:42 AM, limodou wrote:
> On Thu, Apr 12, 2012 at 10:37 PM, Michael Bayer
> <mike...@zzzcomputing.com> wrote:
>>
>> On Apr 12, 2012, at 4:07 AM, limodou wrote:
>>
>>> I'm using alembic today, and I found a problem, if I changed the
>>> column, it'll automatically create add and drop statment, just like
>>> this:
>>>
>>> op.add_column('bas_grp_user', sa.Column('username', sa.Integer(),
>>> nullable=False))
>>> op.drop_column('bas_grp_user', u'USERNAME')
>>>
>>> But when I ran the upgrade I got:
>>>
>>> sqlalchemy.exc.OperationalError: (OperationalError) (1060, "Duplicate
>>> column name 'username'") 'ALTER TABLE bas_grp_user ADD COLUMN username
>>> INTEGER NOT NULL' ()
>>
>> this is a column name change - per the documentation, Alembic can't detect
>> these and you need to manually change it to an alter_column(). In this
>> case, there seems to be an odd casing change where the DB is reporting the
>> name as USERNAME in all caps (usually this is oracle or firebird, though
>> alembic should be normalizing these to lowercase....) - but then the
>> database can't distinguish between USERNAME and "username". If this is
>> happening for all your columns then there might be some dialect-related
>> issue at play. Otherwise, if you just changed the name to "USERNAME" in the
>> DB with quotes then this is what you'd get.
>>
>
> I defined the column name as "USERNAME“ at first, then I changed it to
> "username", so it is the thing I want to change. I know the doc says
> it can't detect the column rename, but I think if alembic can put drop
> statement before add statement, it'll ok for this situation. What do
> you think?
dropping the column then recreating it with a new name IMHO is just wrong,
whether or not it works - it needs to be changed to an alter_column regardless.
The two Column objects have totally different names in any case - this is a
rare edge case where the "two different names" happen to be the same in case
insensitive - so there's quirky behavior on the part of the database at play
(what database is this ? I'd love to know how you got this outcome).
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