Re: [sqlalchemy] default NULL
You can create such a table, yes, if you are sure you should:
from sqlalchemy import *
e = create_engine('sqlite:///')
t = Table('foo', MetaData(e), Column('bar', Text))
t.create()
(or skip the last call if you are referencing an existing table in the DB)
The ORM part of SQLAlchemy does require a primary key to be specified. If
the table has no primary key, you can define it in the mapper using the
`primary_key` argument. Either:
class T(object):
pass
from sqlalchemy.orm import mapper
mapper(T, t, primary_key=t.c.bar)
or using declarative:
from sqlalchemy.ext.declarative import declarative_base
Base = declarative_base(e)
class T2(Base):
__table__ = t
__mapper_args__ = {'primary_key': t.c.bar}
(But unless you really know what you're doing, this is not what you should
be doing.)
Regards,
- Gulli
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Re: [sqlalchemy] default NULL
Oh, sorry, my mistake.
Can I create table in sqlalchemy without primary key?
class UserIp(db.Model, UnicodeMixin):
__tablename__ = 'user_ip'
user_id = db.Column(db.Integer, db.ForeignKey('user.id', ondelete='SET
NULL'))
ip = db.Column(postgres.CIDR, nullable=False, server_default='
127.0.0.1/32')
and it raise error:
ArgumentError: Mapper Mapper|UserIp|user_ip could not assemble any primary
key columns for mapped table 'user_ip'
Thanks!
On Fri, Nov 11, 2011 at 2:35 PM, Wichert Akkerman wrote:
> On 11/11/2011 11:20 AM, Alex K wrote:
>
> Thanks, but if I need allow nullable primary_keys it not works.
> I tried:
> user_id = db.Column(db.Integer, db.ForeignKey('user.id', ondelete='SET
> NULL'), primary_key=True, nullable=True, server_default=text('NULL'))
>
>
> A primary key can never be null. The PostgreSQL documentation describes
> this as follows: "Technically, a primary key constraint is simply a
> combination of a unique constraint and a not-null constraint.".
>
> I suggest that you replace primary_key=True with unique=True.
>
> Wichert.
>
>
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Re: [sqlalchemy] default NULL
On 11/11/2011 11:20 AM, Alex K wrote:
Thanks, but if I need allow nullable primary_keys it not works.
I tried:
user_id = db.Column(db.Integer, db.ForeignKey('user.id
', ondelete='SET NULL'), primary_key=True,
nullable=True, server_default=text('NULL'))
A primary key can never be null. The PostgreSQL documentation describes
this as follows: "Technically, a primary key constraint is simply a
combination of a unique constraint and a not-null constraint.".
I suggest that you replace primary_key=True with unique=True.
Wichert.
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Re: [sqlalchemy] default NULL
Thanks, but if I need allow nullable primary_keys it not works.
I tried:
user_id = db.Column(db.Integer, db.ForeignKey('user.id', ondelete='SET
NULL'), primary_key=True, nullable=True, server_default=text('NULL'))
it generates
CREATE TABLE user_ip (
user_id INTEGER DEFAULT NULL,
PRIMARY KEY (user_id),
FOREIGN KEY(user_id) REFERENCES "user" (id) ON DELETE SET NULL
)
and I see in pgsql modifiers "not null":
\d user_ip
Table "public.user_ip"
Column | Type | Modifiers
-+-+---
user_id | integer | not null
Indexes:
"user_ip_pkey" PRIMARY KEY, btree (user_id)
Foreign-key constraints:
"user_ip_user_id_fkey" FOREIGN KEY (user_id) REFERENCES "user"(id) ON
DELETE SET NULL
Can sqlalchemy allow nullable primary_keys?
Or table without primary key?
Thanks.
On Fri, Nov 11, 2011 at 12:54 AM, Michael Bayer wrote:
>
> 1. time_last = Column(DateTime, nullable=True, server_default=text('NULL'))
>
> 2. all columns in a relational database default to NULL so not sure why
> you'd need to do this.
>
>
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Re: [sqlalchemy] default NULL
On Nov 10, 2011, at 2:09 AM, lestat wrote:
> How I can add default NULL for column?
>
> class UserIp(db.Model, UnicodeMixin):
>__tablename__ = 'user_ip'
>
>user_id = db.Column(db.Integer, db.ForeignKey('user.id'),
> primary_key=True, nullable=True, server_default=None)
>ip = db.Column(postgres.CIDR, nullable=False,
> server_default='127.0.0.1/32')
>time_last = db.Column(db.DateTime, nullable=True,
> server_default=None)
>
> I tried server_default=None, default=None, server_default='NULL', and
> it not works.
two things here:
1. time_last = Column(DateTime, nullable=True, server_default=text('NULL'))
2. all columns in a relational database default to NULL so not sure why you'd
need to do this.
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