Question

我有一个SQLAlchemy模型，如 -

class UserFavPlace(db.Model):
    # This model stores the feedback from the user whether he has
    # faved a place or not
    __tablename__ = u'user_fav_places'

    id = db.Column(db.Integer, primary_key = True)
    public_place_id = db.Column(db.Integer, db.ForeignKey(u'public_places.id'))
    user_id = db.Column(db.Integer, db.ForeignKey(u'users.user_id'))
    fav = db.Column(db.Boolean)
    updated_time = db.Column(db.DateTime)

    place = relationship(u'PublicPlace', backref = u'user_fav_places')
    user = relationship(u'User', backref = u'user_fav_places')

然后我将此模型更改为以下内容 -

class UserFavPlace(db.Model):
    # This model stores the feedback from the user whether he has
    # faved a place or not
    __tablename__ = u'user_fav_places'

    public_place_id = db.Column(db.Integer, db.ForeignKey(u'public_places.id'),
            primary_key = True)
    user_id = db.Column(db.Integer, db.ForeignKey(u'users.user_id'),
            primary_key = True)
    fav = db.Column(db.Boolean)
    updated_time = db.Column(db.DateTime)

    place = relationship(u'PublicPlace', backref = u'user_fav_places')
    user = relationship(u'User', backref = u'user_fav_places')

但是，Alembic没有生成正确的升级和降级语句。似乎它没有添加新引入的主键约束。

def upgrade():
    ### commands auto generated by Alembic - please adjust! ###
    op.drop_column('user_fav_places', 'id')
    ### end Alembic commands ###


def downgrade():
    ### commands auto generated by Alembic - please adjust! ###
    op.add_column('user_fav_places', sa.Column('id', mysql.INTEGER(display_width=11), nullable=False))
    ### end Alembic commands ###

我不确定如何添加它。

Answer 1

我发现自动生成对于检测主键/外键更改非常糟糕。哪个没关系，通常你想要自定义那些。

我还没有创建复合主键，但看起来这应该基于doc：

http://alembic.zzzcomputing.com/en/latest/ops.html#alembic.operations.Operations.create_primary_key

op.create_primary_key(
        "pk_user_fav_places", "user_fav_places",
        ["public_place_id", "user_id"]
    )

但是，您可能会遇到另一个问题，我在此处写道：Adding primary key to existing MySQL table in alembic

这可能已在更新版本的alembic中修复，但它可能不允许您在现有表上创建主键（请参阅上面的答案以了解原因）。如果发生这种情况，您可以自己制作SQL并使用op.execute运行它。

希望有所帮助！

Alembic不会生成复合主键

1 个答案: