for ALTER, which is not what you illustrated earlier, server default
comparison is turned off by default as it can be unreliable in some
cases. Turn it on using compare_server_default=True:
http://alembic.zzzcomputing.com/en/latest/api/runtime.html#alembic.runtime.environment.EnvironmentContext.configure.params.compare_server_default
On Thu, Sep 6, 2018 at 12:37 PM, Yingchen Zhang <cevin.che...@gmail.com> wrote:
> like this:
>
> old model:
>
> class TestModel:
>
> ip = db.Column(db.INET, nullable=False)
>
>
> new Model:
>
> class TestModel:
>
> ip = db.Column(db.VARCHAR(), nullable=False, server_default='127.0.0.1')
>
>
> got migration:
>
> op.alter_column('test', 'ip',
> existing_type=postgresql.INET(),
> type_=sa.VARCHAR(),
> nullable=False)
>
>
> no default set.
>
>
> 在 2018年9月6日星期四 UTC+8下午9:54:23，Mike Bayer写道：
>>
>> On Thu, Sep 6, 2018 at 3:50 AM, Yingchen Zhang <cevin....@gmail.com>
>> wrote:
>> > so, alembic not support `default` ( pgsql create columnn ) ?
>>
>> it does. use server_default. "default" in SQLAlchemy refers to a
>> Python-side default.
>>
>>
>> >
>> > 在 2018年9月6日星期四 UTC+8上午12:24:54，Mike Bayer写道：
>> >>
>> >> On Wed, Sep 5, 2018 at 11:51 AM, Yingchen Zhang <cevin....@gmail.com>
>> >> wrote:
>> >> > db.Column('text_column', db.VARCHAR(20), default='test_text',
>> >> > server_default='test_text', nullable=True)
>> >> >
>> >> > but, generated code like:
>> >> >
>> >> > sa.Column('text_column', sa.VARCHAR(20), nullable=True),
>> >>
>> >> I assume you are using Alembic autogeneration. The Python-side
>> >> default "test_text" is not needed in an alembic autogeneration. The
>> >> server_default however will be rendered.
>> >>
>> >>
>> >> I ran your column as given:
>> >>
>> >> target_metadata = MetaData()
>> >>
>> >> Table(
>> >> 't', target_metadata,
>> >> Column('text_column', VARCHAR(20), default='test_text',
>> >> server_default='test_text', nullable=True)
>> >> )
>> >>
>> >> alembic generates:
>> >>
>> >> def upgrade():
>> >> # ### commands auto generated by Alembic - please adjust! ###
>> >> op.create_table('t',
>> >> sa.Column('text_column', sa.VARCHAR(length=20),
>> >> server_default='test_text', nullable=True)
>> >> )
>> >> # ### end Alembic commands ###
>> >>
>> >>
>> >>
>> >> >
>> >> >
>> >> > how to set column default value ?
>> >> >
>> >> > --
>> >> > SQLAlchemy -
>> >> > The Python SQL Toolkit and Object Relational Mapper
>> >> >
>> >> > http://www.sqlalchemy.org/
>> >> >
>> >> > To post example code, please provide an MCVE: Minimal, Complete, and
>> >> > Verifiable Example. See http://stackoverflow.com/help/mcve for a full
>> >> > description.
>> >> > ---
>> >> > 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 sqlalchemy+...@googlegroups.com.
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>> >> > Visit this group at https://groups.google.com/group/sqlalchemy.
>> >> > For more options, visit https://groups.google.com/d/optout.
>> >
>> > --
>> > SQLAlchemy -
>> > The Python SQL Toolkit and Object Relational Mapper
>> >
>> > http://www.sqlalchemy.org/
>> >
>> > To post example code, please provide an MCVE: Minimal, Complete, and
>> > Verifiable Example. See http://stackoverflow.com/help/mcve for a full
>> > description.
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>
> --
> SQLAlchemy -
> The Python SQL Toolkit and Object Relational Mapper
>
> http://www.sqlalchemy.org/
>
> To post example code, please provide an MCVE: Minimal, Complete, and
> Verifiable Example. See http://stackoverflow.com/help/mcve for a full
> description.
> ---
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--
SQLAlchemy -
The Python SQL Toolkit and Object Relational Mapper
http://www.sqlalchemy.org/
To post example code, please provide an MCVE: Minimal, Complete, and Verifiable
Example. See http://stackoverflow.com/help/mcve for a full description.
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