相关疑难解决方法(0)

我试图Alembic第一次使用,并希望使用此处--autogenerate描述的功能

我的项目结构看起来像

project/
       configuration/
                    __init__.py
                    dev.py
                    test.py
       core/
           app/
              models/
                    __init__.py
                    user.py
       db/
          alembic/
                  versions/
                  env.py
          alembic.ini

我使用Flask,并SQLAlchemy和他们的Flask-SQLAlchemy扩展.我的模特User看起来像

class User(UserMixin, db.Model):
    __tablename__ = 'users'
    # noinspection PyShadowingBuiltins
    uuid = Column('uuid', GUID(), default=uuid.uuid4, primary_key=True,
                  unique=True)
    email = Column('email', String, nullable=False, unique=True)
    _password = Column('password', String, nullable=False)
    created_on = Column('created_on', sa.types.DateTime(timezone=True),
                        default=datetime.utcnow())
    last_login = Column('last_login', sa.types.DateTime(timezone=True),
                        onupdate=datetime.utcnow())

如上所述这里,我修改env.py的样子

from configuration import app

alembic_config = config.get_section(config.config_ini_section) …

我试图首次对预先存在的数据库自动生成一个alembic修订版,但是当我运行以下命令时

alembic revision --autogenerate

它会生成一个迁移,尝试在我的数据库中创建每个表和索引.与此类似:

def upgrade():
    ### commands auto generated by Alembic - please adjust! ###
    op.create_table('table1',
    sa.Column('id', sa.SmallInteger(), nullable=False),
    sa.Column('name', sa.String(length=100), nullable=True),
    sa.Column('desc', sa.Text(), nullable=True),
    sa.PrimaryKeyConstraint('id'),
    sa.UniqueConstraint('name'),
    schema='schema1'
    )
    op.create_index(op.f('ix_index1'), 'table1', ['name'], unique=False, schema='schema1')
    ... all my other tables/indexes ..


def downgrade():
    ### commands auto generated by Alembic - please adjust! ###
    op.drop_index(op.f('ix_index1'), table_name='table1', schema='schema1')
    op.drop_table('table1', schema='schema1')
    ... all my other tables/indexes ..

然后,如果我尝试运行迁移,它将失败,因为对象已经存在:

sqlalchemy.exc.ProgrammingError: (ProgrammingError) relation "table1" already exists

所以在我看来,像alembic认为我的数据库不包含任何表,但确实如此.

任何想法为什么会这样？

我在创建初始迁移时遇到问题,该迁移会自动拥有我在models.py中使用共享Base(declarative_base)定义的表.

当我输入命令时:

alembic revision --autogenerate

alembic创建一个空文件.

我的配置或方法有什么问题？

project.base.py:

from sqlalchemy.ext.declarative import declarative_base


Base = declarative_base()

env.py:

import sys
import os

sys.path.append(os.path.abspath(os.getcwd()))
from alembic import context
from sqlalchemy import engine_from_config, pool
from logging.config import fileConfig

from project.base import Base
target_metadata = Base.metadata
def run_migrations_online():
    """Run migrations in 'online' mode.

    In this scenario we need to create an Engine
    and associate a connection with the context.

    """
    engine = engine_from_config(
        config.get_section(config.config_ini_section),
        prefix='sqlalchemy.',
        poolclass=pool.NullPool)

    connection = engine.connect()
    context.configure(
        connection=connection,
        target_metadata=target_metadata
    )

    # target_metadata.reflect(engine, …