Unless you provide a name, the constraint will be anonymously named, so
there is no difference between that and the shortcut.
Provide a name argument to UniqueConstraint:
__table_args__ = (UniqueConstraint('alt_id', name='uq_alt_id'),)
You may also be interested in providing a naming convention to automate
this:
http://docs.sqlalchemy.org/en/latest/core/constraints.html#configuring-constraint-naming-conventions
On Sunday, May 17, 2015 at 7:49:39 PM UTC-5, [email protected] wrote:
>
> Sorry it took my a while to test this, but I didn't see any difference in
> the SQL emitted. What did I miss?
>
> from sqlalchemy.ext.declarative import declarative_base
> from sqlalchemy import Column
> from sqlalchemy import Integer
> from sqlalchemy import UniqueConstraint
> from sqlalchemy import create_engine
>
> Base = declarative_base()
>
>
> class Test1(Base):
> __tablename__ = 'test_1'
>
> id = Column(Integer, primary_key=True)
> alt_id = Column(Integer, nullable=True, default=None, unique=True)
>
>
> class Test2(Base):
> __tablename__ = 'test_2'
>
> id = Column(Integer, primary_key=True)
> alt_id = Column(Integer, nullable=True, default=None)
>
> __table_args__ = (UniqueConstraint('alt_id'),)
>
> active_db_url = 'postgres://user:[email protected]/db'
> engine = create_engine(active_db_url, echo=False)
>
> Base.metadata.drop_all(engine)
> Base.metadata.create_all(engine)
>
> And here's what I see in the log:
> CREATE TABLE test_2 (
> id SERIAL NOT NULL,
> alt_id INTEGER,
> PRIMARY KEY (id),
> UNIQUE (alt_id)
> )
>
> REATE TABLE test_1 (
> id SERIAL NOT NULL,
> alt_id INTEGER,
> PRIMARY KEY (id),
> UNIQUE (alt_id)
> )
>
>
>
>
> On Sunday, May 3, 2015 at 10:23:31 PM UTC-5, Michael Bayer wrote:
>>
>> sure, use UniqueConstraint directly. It's better to use that than the
>> unique=True flag in any case.
>>
>>
>>
>> On 5/3/15 10:29 PM, [email protected] wrote:
>>
>> Is there a way to control whether DDL emitted by SQLAlchemy uses a
>> column and/or table constraint for uniqueness?
>>
>> It seems the following
>> class Part(Base):
>> __tablename__ = 'part'
>> third_party_id = Column(Integer, nullable=True, default=None, unique=
>> True)
>>
>>
>> emits a table constraint
>> CREATE TABLE part (
>> third_party_id INTEGER,
>> CONSTRAINT uq_part_third_party_id UNIQUE (third_party_id)
>> )
>>
>>
>>
>>
>> Is it possible to emit the following with a column constraint instead?
>> CREATE TABLE part (
>> third_party_id INTEGER CONSTRAINT uq_part_third_party_id UNIQUE
>> )
>>
>> Thanks
>> --
>> You received this message because you are subscribed to the Google Groups
>> "sqlalchemy" group.
>> To unsubscribe from this group and stop receiving emails from it, send an
>> email to [email protected].
>> To post to this group, send email to [email protected].
>> Visit this group at http://groups.google.com/group/sqlalchemy.
>> For more options, visit https://groups.google.com/d/optout.
>>
>>
>>
--
You received this message because you are subscribed to the Google Groups
"sqlalchemy" group.
To unsubscribe from this group and stop receiving emails from it, send an email
to [email protected].
To post to this group, send email to [email protected].
Visit this group at http://groups.google.com/group/sqlalchemy.
For more options, visit https://groups.google.com/d/optout.
