Python sqlalchemy的alembic不'；t检测柱的添加和删除

我定义了流动模型

class JjfqServiceProvidorRecord(Base):
    __tablename__ = 'jjfq_service_providor_record'
    id = Column(Integer, primary_key=True)
    phone = Column(String(16))
    name = Column(String(20))

然后我运行了

alembic revision--autogenerate-m'first'

，得到了流动的迁移文件：

def upgrade():
    ### commands auto generated by Alembic - please adjust! ###
    op.create_table('jjfq_service_providor_record',
    sa.Column('id', sa.Integer(), nullable=False),
    sa.Column('phone', sa.String(length=16), nullable=True),
    sa.Column('name', sa.String(length=20), nullable=True),
    sa.PrimaryKeyConstraint('id')
    )
    ### end Alembic commands ###

def downgrade():
    ### commands auto generated by Alembic - please adjust! ###
    op.drop_table('jjfq_service_providor_record')
    ### end Alembic commands ###

然后，我删除

name

字段，如下所示：

class JjfqServiceProvidorRecord(Base):
    __tablename__ = 'jjfq_service_providor_record'
    id = Column(Integer, primary_key=True)
    phone = Column(String(16))
    name = Column(String(20))

然后我重新运行

alembic revision--autogenerate-m'second'

，该命令生成的迁移文件是：

def upgrade():
    ### commands auto generated by Alembic - please adjust! ###
    pass
    ### end Alembic commands ###


def downgrade():
    ### commands auto generated by Alembic - please adjust! ###
    pass
    ### end Alembic commands ###

怎么了？为什么alembic没有检测到列的添加和删除

python:python 2.7.5
alembic：最新的verison
sqlalchemy:1.0
框架：猎鹰
系统：Debian GNU/Linux 7

---

首先，我将描述我的环境：

OS X El Capitan
MySQL Server 5.7
alembic (0.8.6)
PyMySQL (0.7.2)
SQLAlchemy (1.0.12)

这是安装和初始化Alembic后我的目录结构：

.
├── __init__.py
├── alembic
│   ├── README
│   ├── env.py
│   ├── script.py.mako
│   └── versions
├── alembic.ini
├── app
│   ├── __init__.py
│   └── models.py
└── requirements.txt

3 directories, 9 files

我已经在app/models.py中定义了模型：

from sqlalchemy import Column, String, Integer
from sqlalchemy.ext.declarative import declarative_base

Base = declarative_base()

class JjfqServiceProvidorRecord(Base):
    __tablename__ = 'jjfq_service_providor_record'
    id = Column(Integer, primary_key=True)
    phone = Column(String(16))
    name = Column(String(20))

对于

alembic/env.py

，我有以下内容：

from app import *
from app.models import Base
target_metadata = Base.metadata

之后，我运行了autogeneration命令：

$ alembic revision --autogenerate -m 'first'
INFO  [alembic.runtime.migration] Context impl MySQLImpl.
INFO  [alembic.runtime.migration] Will assume non-transactional DDL.
INFO  [alembic.autogenerate.compare] Detected added table 'jjfq_service_providor_record'
  Generating /tmp/37027017/alembic/versions/5b157ced3fa0_first.py ... done

第一个迁移文件应如下所示：

"""first

Revision ID: 5b157ced3fa0
Revises: 
Create Date: 2016-05-05 21:53:57.687433

"""

# revision identifiers, used by Alembic.
revision = '5b157ced3fa0'
down_revision = None
branch_labels = None
depends_on = None

from alembic import op
import sqlalchemy as sa


def upgrade():
    ### commands auto generated by Alembic - please adjust! ###
    op.create_table('jjfq_service_providor_record',
    sa.Column('id', sa.Integer(), nullable=False),
    sa.Column('phone', sa.String(length=16), nullable=True),
    sa.Column('name', sa.String(length=20), nullable=True),
    sa.PrimaryKeyConstraint('id')
    )
    ### end Alembic commands ###


def downgrade():
    ### commands auto generated by Alembic - please adjust! ###
    op.drop_table('jjfq_service_providor_record')
    ### end Alembic commands ###

"""second

Revision ID: acbba548b6cd
Revises: 5b157ced3fa0
Create Date: 2016-05-05 21:55:23.130404

"""

# revision identifiers, used by Alembic.
revision = 'acbba548b6cd'
down_revision = '5b157ced3fa0'
branch_labels = None
depends_on = None

from alembic import op
import sqlalchemy as sa
from sqlalchemy.dialects import mysql

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


def downgrade():
    ### commands auto generated by Alembic - please adjust! ###
    op.add_column('jjfq_service_providor_record', sa.Column('name', mysql.VARCHAR(length=20), nullable=True))
    ### end Alembic commands ###

如果您对第一个迁移文件的外观感到满意，请运行升级迁移：

$ alembic upgrade head
INFO  [alembic.runtime.migration] Context impl MySQLImpl.
INFO  [alembic.runtime.migration] Will assume non-transactional DDL.
INFO  [alembic.runtime.migration] Running upgrade  -> 5b157ced3fa0, first

之后，您可以从

app/models.py

中的表定义中删除

jjfq\u service\u providor\u record.name

列，并运行第二次自动生成：

$ alembic revision --autogenerate -m 'second'
INFO  [alembic.runtime.migration] Context impl MySQLImpl.
INFO  [alembic.runtime.migration] Will assume non-transactional DDL.
INFO  [alembic.autogenerate.compare] Detected removed column 'jjfq_service_providor_record.name'
  Generating /tmp/37027017/alembic/versions/acbba548b6cd_second.py ... done

第二个迁移文件应如下所示：

"""first

Revision ID: 5b157ced3fa0
Revises: 
Create Date: 2016-05-05 21:53:57.687433

"""

# revision identifiers, used by Alembic.
revision = '5b157ced3fa0'
down_revision = None
branch_labels = None
depends_on = None

from alembic import op
import sqlalchemy as sa


def upgrade():
    ### commands auto generated by Alembic - please adjust! ###
    op.create_table('jjfq_service_providor_record',
    sa.Column('id', sa.Integer(), nullable=False),
    sa.Column('phone', sa.String(length=16), nullable=True),
    sa.Column('name', sa.String(length=20), nullable=True),
    sa.PrimaryKeyConstraint('id')
    )
    ### end Alembic commands ###


def downgrade():
    ### commands auto generated by Alembic - please adjust! ###
    op.drop_table('jjfq_service_providor_record')
    ### end Alembic commands ###

"""second

Revision ID: acbba548b6cd
Revises: 5b157ced3fa0
Create Date: 2016-05-05 21:55:23.130404

"""

# revision identifiers, used by Alembic.
revision = 'acbba548b6cd'
down_revision = '5b157ced3fa0'
branch_labels = None
depends_on = None

from alembic import op
import sqlalchemy as sa
from sqlalchemy.dialects import mysql

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


def downgrade():
    ### commands auto generated by Alembic - please adjust! ###
    op.add_column('jjfq_service_providor_record', sa.Column('name', mysql.VARCHAR(length=20), nullable=True))
    ### end Alembic commands ###

如果这看起来也不错，那么运行第二次迁移，您应该已经准备好了

$ alembic upgrade head
INFO  [alembic.runtime.migration] Context impl MySQLImpl.
INFO  [alembic.runtime.migration] Will assume non-transactional DDL.
INFO  [alembic.runtime.migration] Running upgrade 5b157ced3fa0 -> acbba548b6cd, second

正如您所看到的，我的第二次修订版中的注释“second”是经过深思熟虑的，它帮助我更准确地记录了删除

名称

列的过程。我认为，当您试图确定迁移历史时，它会让您更清楚

---

希望有帮助

首先，我将描述我的环境：

OS X El Capitan
MySQL Server 5.7
alembic (0.8.6)
PyMySQL (0.7.2)
SQLAlchemy (1.0.12)

这是安装和初始化Alembic后我的目录结构：

.
├── __init__.py
├── alembic
│   ├── README
│   ├── env.py
│   ├── script.py.mako
│   └── versions
├── alembic.ini
├── app
│   ├── __init__.py
│   └── models.py
└── requirements.txt

3 directories, 9 files

我已经在app/models.py中定义了模型：

from sqlalchemy import Column, String, Integer
from sqlalchemy.ext.declarative import declarative_base

Base = declarative_base()

class JjfqServiceProvidorRecord(Base):
    __tablename__ = 'jjfq_service_providor_record'
    id = Column(Integer, primary_key=True)
    phone = Column(String(16))
    name = Column(String(20))

对于

alembic/env.py

，我有以下内容：

from app import *
from app.models import Base
target_metadata = Base.metadata

之后，我运行了autogeneration命令：

$ alembic revision --autogenerate -m 'first'
INFO  [alembic.runtime.migration] Context impl MySQLImpl.
INFO  [alembic.runtime.migration] Will assume non-transactional DDL.
INFO  [alembic.autogenerate.compare] Detected added table 'jjfq_service_providor_record'
  Generating /tmp/37027017/alembic/versions/5b157ced3fa0_first.py ... done

第一个迁移文件应如下所示：

"""first

Revision ID: 5b157ced3fa0
Revises: 
Create Date: 2016-05-05 21:53:57.687433

"""

# revision identifiers, used by Alembic.
revision = '5b157ced3fa0'
down_revision = None
branch_labels = None
depends_on = None

from alembic import op
import sqlalchemy as sa


def upgrade():
    ### commands auto generated by Alembic - please adjust! ###
    op.create_table('jjfq_service_providor_record',
    sa.Column('id', sa.Integer(), nullable=False),
    sa.Column('phone', sa.String(length=16), nullable=True),
    sa.Column('name', sa.String(length=20), nullable=True),
    sa.PrimaryKeyConstraint('id')
    )
    ### end Alembic commands ###


def downgrade():
    ### commands auto generated by Alembic - please adjust! ###
    op.drop_table('jjfq_service_providor_record')
    ### end Alembic commands ###

"""second

Revision ID: acbba548b6cd
Revises: 5b157ced3fa0
Create Date: 2016-05-05 21:55:23.130404

"""

# revision identifiers, used by Alembic.
revision = 'acbba548b6cd'
down_revision = '5b157ced3fa0'
branch_labels = None
depends_on = None

from alembic import op
import sqlalchemy as sa
from sqlalchemy.dialects import mysql

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


def downgrade():
    ### commands auto generated by Alembic - please adjust! ###
    op.add_column('jjfq_service_providor_record', sa.Column('name', mysql.VARCHAR(length=20), nullable=True))
    ### end Alembic commands ###

如果您对第一个迁移文件的外观感到满意，请运行升级迁移：

$ alembic upgrade head
INFO  [alembic.runtime.migration] Context impl MySQLImpl.
INFO  [alembic.runtime.migration] Will assume non-transactional DDL.
INFO  [alembic.runtime.migration] Running upgrade  -> 5b157ced3fa0, first

之后，您可以从

app/models.py

中的表定义中删除

jjfq\u service\u providor\u record.name

列，并运行第二次自动生成：

$ alembic revision --autogenerate -m 'second'
INFO  [alembic.runtime.migration] Context impl MySQLImpl.
INFO  [alembic.runtime.migration] Will assume non-transactional DDL.
INFO  [alembic.autogenerate.compare] Detected removed column 'jjfq_service_providor_record.name'
  Generating /tmp/37027017/alembic/versions/acbba548b6cd_second.py ... done

第二个迁移文件应如下所示：

"""first

Revision ID: 5b157ced3fa0
Revises: 
Create Date: 2016-05-05 21:53:57.687433

"""

# revision identifiers, used by Alembic.
revision = '5b157ced3fa0'
down_revision = None
branch_labels = None
depends_on = None

from alembic import op
import sqlalchemy as sa


def upgrade():
    ### commands auto generated by Alembic - please adjust! ###
    op.create_table('jjfq_service_providor_record',
    sa.Column('id', sa.Integer(), nullable=False),
    sa.Column('phone', sa.String(length=16), nullable=True),
    sa.Column('name', sa.String(length=20), nullable=True),
    sa.PrimaryKeyConstraint('id')
    )
    ### end Alembic commands ###


def downgrade():
    ### commands auto generated by Alembic - please adjust! ###
    op.drop_table('jjfq_service_providor_record')
    ### end Alembic commands ###

"""second

Revision ID: acbba548b6cd
Revises: 5b157ced3fa0
Create Date: 2016-05-05 21:55:23.130404

"""

# revision identifiers, used by Alembic.
revision = 'acbba548b6cd'
down_revision = '5b157ced3fa0'
branch_labels = None
depends_on = None

from alembic import op
import sqlalchemy as sa
from sqlalchemy.dialects import mysql

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


def downgrade():
    ### commands auto generated by Alembic - please adjust! ###
    op.add_column('jjfq_service_providor_record', sa.Column('name', mysql.VARCHAR(length=20), nullable=True))
    ### end Alembic commands ###

如果这看起来也不错，那么运行第二次迁移，您应该已经准备好了

$ alembic upgrade head
INFO  [alembic.runtime.migration] Context impl MySQLImpl.
INFO  [alembic.runtime.migration] Will assume non-transactional DDL.
INFO  [alembic.runtime.migration] Running upgrade 5b157ced3fa0 -> acbba548b6cd, second

正如您所看到的，我的第二次修订版中的注释“second”是经过深思熟虑的，它帮助我更准确地记录了删除

名称

列的过程。我认为，当您试图确定迁移历史时，它会让您更清楚

---

希望有帮助

噢，我终于找到问题了。My sys.path指向错误的目录，其中是旧版本的代码。所以每次我运行alembic revision--autogenerate时，它都会读取未修改的旧代码。

哦，最后我发现了问题。My sys.path指向错误的目录，其中是旧版本的代码。因此，每次我运行

alembic revision--autogenerate

，它都会读取未修改的旧代码。

如何在base.py中定义jjfq_service_providor_记录并在model.py中删除jjfq_service_providor_record.name？请告诉我我的答案是否令人满意。如果没有，请说明原因。谢谢，我跟着你走。但第二次迁移仍然是空的。我已经更新了我的问题@约翰·A.@dae-Hmm……这很有趣。请尝试查看alembic current的内容。它应该指向

标题

，在本例中是第二次修订版

acbba548b6cd

。如果所有其他操作都失败，您应该尝试删除

alembic\u version

数据库表并从头开始。哦，我知道为什么。My sys.path指向错误的目录，其中是旧版本的代码。谢谢你的回答@John A.您如何在base.py中定义jjfq_service_providor_记录并在model.py中删除jjfq_service_providor_记录.name？@dae如果我的回答令人满意，请告诉我。如果没有，请说明原因。谢谢，我跟着你走。但第二次迁移仍然是空的。我已经更新了我的问题@约翰·A.@dae-Hmm……这很有趣。请尝试查看alembic current的内容。它应该指向

标题

，在本例中是第二次修订版

acbba548b6cd

。如果所有其他操作都失败，您应该尝试删除

alembic\u version

数据库表并从头开始。哦，我知道为什么。My sys.path指向错误的目录，其中是旧版本的代码。谢谢你的回答@约翰A。