Gulli,
Thank you so much for the helpful information. I think that the "type_"
argument should cause an explicit cast if it's on a default array empty list
value; that very much was my expectation, unfortunately!
I've discovered what appears to be very strange & unexpected behavior:
mycol = Column('mycol', ARRAY(Integer), default=[], nullable=False) # does work
mycol = Column('mycol', ARRAY(Integer), default=array([], type_=Integer),
nullable=False) # doesn't work (?!)
It's very strange, because adding more information to the default argument
value causes things to break, whereas a simple empty array ends up acquiring
whatever ARRAY casts it needs to work. In the end we decided to go with the
following solution, which is similar to what you suggested and does appear to
work:
mycol = Column('mycol', ARRAY(Integer), default=cast(array([], type_=Integer),
ARRAY(Integer)), nullable=False)
Thanks again for your time and reply,
Mike
________________________________
From: sqlalchemy@googlegroups.com [sqlalchemy@googlegroups.com] on behalf of
Gunnlaugur Thor Briem [gunnlau...@gmail.com]
Sent: Tuesday, December 03, 2013 8:35 AM
To: sqlalchemy
Subject: Re: [sqlalchemy] "ProgrammingError: cannot determine type of empty
array" even with proper model declaration?
Hi,
1. the server_default=... argument just says what default to define for the
column *on creation* --- it has no effect if the table already exists. To apply
the default to an existing table, you need to execute something like:
ALTER TABLE mytbl ALTER COLUMN mycol ADD DEFAULT ARRAY[]::integer[];
2. the server-side default has no effect if you configure SQLAlchemy to always
specify a value for the column (which is what the default=... argument does).
So you could either (a) alter the table and skip the default=... argument, or
(b) change the default=... argument to literal SQL with an explicit cast, e.g.
default=literal_column("'{}'::integer[]") (because array() doesn't get compiled
with an explicit typecast, even if you give it an explicit type_ ... maybe it
should, when the array is empty.)
Cheers,
Gulli
On Tue, Dec 3, 2013 at 1:10 PM, Michael Nachtigal
<michael.nachti...@catalinamarketing.com<mailto:michael.nachti...@catalinamarketing.com>>
wrote:
Hello, all,
I'm receiving this error:
ProgrammingError: (ProgrammingError) cannot determine type of empty array
It looks like this is happening because the default value for column in new
instances of one of my models is being initialized to [] (an empty array, no
inner type), despite my column being defined like this in the model class:
mycol = Column('mycol',
ARRAY(Integer),
server_default=text('ARRAY[]::integer[]'),
default=array([], type_=Integer),
nullable=False)
I've tried it with both the "default" and "server_default" kwargs, with only
the "default" kwarg, and with only the "server_default" kwargs, and it seems
not to make a difference (and I'm not sure really which combination of
arguments would be most appropriate here, anyway, but that's not the primary
reason for my question). The column in the database is defined like this:
mycol integer array NOT NULL
I would appreciate any kind of help or information anyone could provide to help
me solve this.
Thanks,
Mike
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