将Alembic与SQLAlchemy集成 [英] Integrating Alembic with SQLAlchemy

问题描述

我正在寻找一种将Alembic与SQLAlchemy集成的方法.我需要的是一种方法，以便Alembic自动检测我在models.py中所做的任何更改，并在运行alembic revision -m "<message_here>"和alembic upgrade head时在MySQL数据库中对其进行更新.

I'm looking at a way to integrate Alembic with SQLAlchemy. What I need is a way so that Alembic detects any changes I make in models.py automatically and updates it in the MySQL database when I run alembic revision -m "<message_here>" and alembic upgrade head.

这是我现在的位置.

这是我的应用程序目录结构.

This is my application directory structure.

/myapplication
    models.py
    __init__.py
    app.py
    /migrations
        env.py
        script.py.mako
        /versions

models.py包含以下内容.

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

Base = declarative_base()

class User(Base):
    """ `User` stores the basic info about a user
    """
    __tablename__ = 'user'
    id = Column(Integer, primary_key=True)
    name = Column(String(255), nullable=False)
    phone = Column(String(15), nullable=False)

我已经用sqlalchemy.url

我的env.py

from __future__ import with_statement
from alembic import context
from sqlalchemy import engine_from_config, pool
from logging.config import fileConfig
from myapplication import models

# this is the Alembic Config object, which provides
# access to the values within the .ini file in use.
config = context.config

# Interpret the config file for Python logging.
# This line sets up loggers basically.
fileConfig(config.config_file_name)

# add your model's MetaData object here
# for 'autogenerate' support
# from myapp import mymodel
# target_metadata = mymodel.Base.metadata
target_metadata = models.Base.metadata

# other values from the config, defined by the needs of env.py,
# can be acquired:
# my_important_option = config.get_main_option("my_important_option")
# ... etc.

def run_migrations_offline():
    """Run migrations in 'offline' mode.

    This configures the context with just a URL
    and not an Engine, though an Engine is acceptable
    here as well.  By skipping the Engine creation
    we don't even need a DBAPI to be available.

    Calls to context.execute() here emit the given string to the
    script output.

    """
    url = config.get_main_option("sqlalchemy.url")
    context.configure(url=url)

    with context.begin_transaction():
        context.run_migrations()

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
                )

    try:
        with context.begin_transaction():
            context.run_migrations()
    finally:
        connection.close()

if context.is_offline_mode():
    run_migrations_offline()
else:
    run_migrations_online()

但是在运行迁移时使用

alembic revision -m "initial"

说

Generating
migrations/versions/2d9d8de1aa80_initial.py...done

但是当我打开migrations/versions/9aa5864e4c8_initial.py时，这就是我看到的.

But when I open the migrations/versions/9aa5864e4c8_initial.py, this is what I see.

"""initial

Revision ID: 2d9d8de1aa80
Revises: None
Create Date: 2013-02-23 12:21:52.389906

"""

# revision identifiers, used by Alembic.
revision = '2d9d8de1aa80'
down_revision = None

from alembic import op
import sqlalchemy as sa


def upgrade():
    pass


def downgrade():
    pass

版本文件与我期望它创建的表没有任何关系，以后当我运行命令alembic upgrade head时与MySQL同步.如何配置Alembic，以便在运行alembic revision命令时，它从models.py中选择架构并生成版本文件?我想我在这里错过了一些琐碎的事情.不知道是什么！

The version file has nothing about the tables I was expecting it to create and later sync with MySQL when I run the command alembic upgrade head. How do I configure Alembic so that when I run the alembic revision command, It picks the schema from models.py and generates a version file? I think I am missing something trivial here. Not sure what it is!

推荐答案

您要使用--autogenerate标志运行version子命令，以便它检查模型的更改.

You want to run the revision subcommand with the --autogenerate flag so it inspects the models for changes.

alembic revision --autogenerate -m "some message"

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