Alembic 反转 upgrade/downgrade (Flask-SQLAlchemy)
Alembic inverting upgrade/downgrade (Flask-SQLAlchemy)
我最近一直在与 Alembic 作斗争，我不知道为什么它会反转正确的 upgrade/downgrade 更改。
我在用户模型中创建了 2 个新字段（about_me、last_seen），运行 'flask db migrate' 然后查看版本文件我可以看到正确的迁移是降级而不是升级。
我已经尝试 运行 db.create_all、db.drop_all、删除 alembic_version table 但没有成功。每次在下面得到相同的结果时，我应该在降级中使用 DROP_TABLE 命令，在升级中使用 CREATE_TABLE 命令。
我目前能够让它工作的唯一方法是删除所需的 tables，然后手动复制并粘贴从降级到升级的代码。
迁移文件：
def upgrade():
# ### commands auto generated by Alembic - please adjust! ###
op.drop_table('tutor_category')
op.drop_table('tutors')
op.drop_index('ix_categories_name', table_name='categories')
op.drop_table('categories')
op.drop_index('ix_users_email', table_name='users')
op.drop_index('ix_users_first_name', table_name='users')
op.drop_index('ix_users_last_name', table_name='users')
op.drop_index('ix_users_timestamp_joined', table_name='users')
op.drop_table('users')
op.drop_index('ix_reviews_rating', table_name='reviews')
op.drop_index('ix_reviews_timestamp', table_name='reviews')
op.drop_table('reviews')
# ### end Alembic commands ###
def downgrade():
# ### commands auto generated by Alembic - please adjust! ###
op.create_table('reviews',
sa.Column('id', sa.INTEGER(), autoincrement=True, nullable=False),
sa.Column('user_id', sa.INTEGER(), autoincrement=False, nullable=True),
sa.Column('tutor_id', sa.INTEGER(), autoincrement=False, nullable=True),
sa.Column('rating', sa.INTEGER(), autoincrement=False, nullable=True),
sa.Column('timestamp', postgresql.TIMESTAMP(), autoincrement=False, nullable=True),
sa.ForeignKeyConstraint(['tutor_id'], ['tutors.id'], name='reviews_tutor_id_fkey'),
sa.ForeignKeyConstraint(['user_id'], ['users.id'], name='reviews_user_id_fkey'),
sa.PrimaryKeyConstraint('id', name='reviews_pkey')
)
op.create_index('ix_reviews_timestamp', 'reviews', ['timestamp'], unique=False)
op.create_index('ix_reviews_rating', 'reviews', ['rating'], unique=False)
op.create_table('users',
sa.Column('id', sa.INTEGER(), server_default=sa.text("nextval('users_id_seq'::regclass)"), autoincrement=True, nullable=False),
sa.Column('first_name', sa.VARCHAR(length=64), autoincrement=False, nullable=False),
sa.Column('last_name', sa.VARCHAR(length=64), autoincrement=False, nullable=False),
sa.Column('email', sa.VARCHAR(length=120), autoincrement=False, nullable=False),
sa.Column('profile_img', sa.VARCHAR(length=120), autoincrement=False, nullable=True),
sa.Column('password_hash', sa.VARCHAR(length=128), autoincrement=False, nullable=False),
sa.Column('timestamp_joined', postgresql.TIMESTAMP(), autoincrement=False, nullable=True),
sa.Column('about_me', sa.VARCHAR(length=140), autoincrement=False, nullable=True),
sa.Column('last_seen', postgresql.TIMESTAMP(timezone=True), autoincrement=False, nullable=True),
sa.PrimaryKeyConstraint('id', name='users_pkey'),
postgresql_ignore_search_path=False
)
op.create_index('ix_users_timestamp_joined', 'users', ['timestamp_joined'], unique=False)
op.create_index('ix_users_last_name', 'users', ['last_name'], unique=False)
op.create_index('ix_users_first_name', 'users', ['first_name'], unique=False)
op.create_index('ix_users_email', 'users', ['email'], unique=True)
op.create_table('categories',
sa.Column('id', sa.INTEGER(), server_default=sa.text("nextval('categories_id_seq'::regclass)"), autoincrement=True, nullable=False),
sa.Column('name', sa.VARCHAR(length=64), autoincrement=False, nullable=True),
sa.PrimaryKeyConstraint('id', name='categories_pkey'),
postgresql_ignore_search_path=False
)
op.create_index('ix_categories_name', 'categories', ['name'], unique=False)
op.create_table('tutors',
sa.Column('id', sa.INTEGER(), server_default=sa.text("nextval('tutors_id_seq'::regclass)"), autoincrement=True, nullable=False),
sa.Column('user_id', sa.INTEGER(), autoincrement=False, nullable=True),
sa.Column('price', postgresql.DOUBLE_PRECISION(precision=53), autoincrement=False, nullable=True),
sa.ForeignKeyConstraint(['user_id'], ['users.id'], name='tutors_user_id_fkey'),
sa.PrimaryKeyConstraint('id', name='tutors_pkey'),
postgresql_ignore_search_path=False
)
op.create_table('tutor_category',
sa.Column('tutor_id', sa.INTEGER(), autoincrement=False, nullable=False),
sa.Column('category_id', sa.INTEGER(), autoincrement=False, nullable=False),
sa.ForeignKeyConstraint(['category_id'], ['categories.id'], name='tutor_category_category_id_fkey'),
sa.ForeignKeyConstraint(['tutor_id'], ['tutors.id'], name='tutor_category_tutor_id_fkey'),
sa.PrimaryKeyConstraint('tutor_id', 'category_id', name='tutor_category_pkey')
)
# ### end Alembic commands ###
Models.py
class Users(UserMixin, db.Model):
__tablename__ = 'users'
id = db.Column(db.Integer, primary_key=True)
first_name = db.Column(db.String(64), index=True, nullable=False)
last_name = db.Column(db.String(64), index=True, nullable=False)
email = db.Column(db.String(120), index=True, unique=True, nullable=False)
profile_img = db.Column(db.String(120), nullable=True)
password_hash = db.Column(db.String(128), nullable=False)
timestamp_joined = db.Column(db.DateTime, index=True, default=datetime.utcnow)
about_me = db.Column(db.String(140), nullable=True)
last_seen = db.Column(db.DateTime(140), default=datetime.utcnow)
def set_password(self, password):
self.password_hash = generate_password_hash(password)
def check_password(self, password):
return check_password_hash(self.password_hash, password)
def avatar(self):
digest = md5(self.email.lower().encode('utf-8')).hexdigest()
return 'https://www.gravatar.com/avatar/{}?d=identicon'.format(
digest)
def __repr__(self):
return '<User {}>'.format(self.username)
class Tutors(db.Model):
__tablename__ = 'tutors'
id = db.Column(db.Integer, primary_key=True)
user_id = db.Column(db.Integer, db.ForeignKey('users.id'))
price = db.Column(db.Float)
# Connecting this field to the association table.
category = db.relationship("Categories", secondary="tutor_category")
def __repr__(self):
return '<Tutor id {}'.format(self.user_id) + ' , price {}>'.format(self.price)
class Reviews(db.Model):
__tablename__ = 'reviews'
id = db.Column(db.Integer, primary_key=True)
user_id = db.Column(db.Integer, db.ForeignKey('users.id'))
tutor_id = db.Column(db.Integer, db.ForeignKey('tutors.id'))
rating = db.Column(db.Integer, index=True)
timestamp = db.Column(db.DateTime, index=True, default=datetime.utcnow)
def __repr__(self):
return '<Review User: {}'.format(self.user_id) + ' Tutor: {}'.format(self.tutor_id) + ' Rating: {}>'.format(self.rating)
class Categories(db.Model):
__tablename__ = 'categories'
id = db.Column(db.Integer, primary_key=True)
name = db.Column(db.String(64), index=True)
# Connecting this field to the association table.
tutor = db.relationship('Tutors', secondary="tutor_category")
def __repr__(self):
return '<Category {}>'.format(self.name)
# Declaring the association table
tutor_category = db.Table('tutor_category',
db.Column('tutor_id', db.Integer, db.ForeignKey('tutors.id'), primary_key=True),
db.Column('category_id', db.Integer, db.ForeignKey('categories.id'), primary_key=True)
)
@login.user_loader
def load_user(id):
return Users.query.get(int(id))
Manage.py
from flask import Flask
from flask_script import Manager
from flask_migrate import Migrate, MigrateCommand
from flask_sqlalchemy import SQLAlchemy
from app import app
from app import models
db = SQLAlchemy(app)
POSTGRES = {
'user': 'richard',
'pw': 'richard2906',
'db': 'codetutors',
'host': 'localhost',
'port': '5432',
}
app.config['SQLALCHEMY_DATABASE_URI'] = 'postgresql://%(user)s:\
%(pw)s@%(host)s:%(port)s/%(db)s' % POSTGRES
app.config['SQLALCHEMY_TRACK_MODIFICATIONS'] = False
migrate = Migrate(app, db)
manager = Manager(app)
db.init_app(app)
manager.add_command('db', MigrateCommand)
def create_app():
app = Flask(__name__)
app.config['DEBUG'] = True
app.config['SQLALCHEMY_DATABASE_URI'] = 'postgresql://%(user)s:\
%(pw)s@%(host)s:%(port)s/%(db)s' % POSTGRES
app.config['SQLALCHEMY_TRACK_MODIFICATIONS'] = False
db = SQLAlchemy(app)
db.init_app(app)
return app
if __name__ == '__main__':
manager.run()
env.py
from __future__ import with_statement
import logging
from logging.config import fileConfig
from sqlalchemy import engine_from_config
from sqlalchemy import pool
from alembic import context
from manage import db
# 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)
logger = logging.getLogger('alembic.env')
# add your model's MetaData object here
# for 'autogenerate' support
# from app.models import Users, Tutors, Categories, Reviews
target_metadata = db.metadata
# from myapp import mymodel
# target_metadata = mymodel.Base.metadata
from flask import current_app
config.set_main_option(
'sqlalchemy.url',
str(current_app.extensions['migrate'].db.engine.url).replace('%', '%%'))
target_metadata = current_app.extensions['migrate'].db.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, target_metadata=target_metadata, literal_binds=True
)
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.
"""
# this callback is used to prevent an auto-migration from being generated
# when there are no changes to the schema
# reference: http://alembic.zzzcomputing.com/en/latest/cookbook.html
def process_revision_directives(context, revision, directives):
if getattr(config.cmd_opts, 'autogenerate', False):
script = directives[0]
if script.upgrade_ops.is_empty():
directives[:] = []
logger.info('No changes in schema detected.')
connectable = engine_from_config(
config.get_section(config.config_ini_section),
prefix='sqlalchemy.',
poolclass=pool.NullPool,
)
with connectable.connect() as connection:
context.configure(
connection=connection,
target_metadata=target_metadata,
process_revision_directives=process_revision_directives,
**current_app.extensions['migrate'].configure_args
)
with context.begin_transaction():
context.run_migrations()
if context.is_offline_mode():
run_migrations_offline()
else:
run_migrations_online()
感谢您的帮助
对于那些遇到类似问题的人，我使用 Flask-Script 管理器作为 'python manage.py db migrate'，然后更改为 'flask db migrate'，应用程序开始正确识别 Models/Tables。
我只是猜测，当您移至 flask db migrate 而不是将 flask_script 与 python3 migrate.py db migrate 一起使用时，您的数据库也发生了变化。
您的数据库（在您提出问题时）似乎已经包含您要迁移的表。当它们存在但不在您的代码中 used/mentioned/imported 时，显然 alembic 删除它们是正确的决定。
从这个角度来看，升级应该删除表，而降级会像以前一样重新创建它们。
始终在迁移脚本中导入模型（使用 flask_script 时）并始终使用 db upgrade 命令应用数据库更改，而不是自己添加表。
这应该会导致正确的升级脚本。
关于您的代码
- 您可以创建自己的
app 而不是导入它
- 您使用了导入的
app 变量来绑定 SQLAlchemy 实例，但您还定义了另一个未使用的 create_app 函数？你也在那个实例上做了一个 db.init_app(app) （即使它是用 SQLAlchemy(app) 创建的
我想这会导致 alembic 查看错误的 app 上下文，其中 none 定义了模型。另外，您的数据库包含此 app.
中未提及的表
这是我的 migrate.py:
from flask import Flask
from flask_script import Manager
from flask_migrate import Migrate, MigrateCommand
from models import * # contains 'db.Model' classes and instance of 'db'
app = Flask(__name__)
config_path = "config.json"
app.config.from_json(config_path)
# db = SQLAlchemy(app) # <-- the "normal way"
db.init_app(app) # <-- most likely if you have defined 'db' already in 'models.py'
migrate = Migrate(app, db)
manager = Manager(app)
manager.add_command('db', MigrateCommand)
if __name__ == '__main__':
manager.run()
我最近一直在与 Alembic 作斗争，我不知道为什么它会反转正确的 upgrade/downgrade 更改。
我在用户模型中创建了 2 个新字段（about_me、last_seen），运行 'flask db migrate' 然后查看版本文件我可以看到正确的迁移是降级而不是升级。
我已经尝试 运行 db.create_all、db.drop_all、删除 alembic_version table 但没有成功。每次在下面得到相同的结果时，我应该在降级中使用 DROP_TABLE 命令，在升级中使用 CREATE_TABLE 命令。
我目前能够让它工作的唯一方法是删除所需的 tables，然后手动复制并粘贴从降级到升级的代码。
迁移文件：
def upgrade():
# ### commands auto generated by Alembic - please adjust! ###
op.drop_table('tutor_category')
op.drop_table('tutors')
op.drop_index('ix_categories_name', table_name='categories')
op.drop_table('categories')
op.drop_index('ix_users_email', table_name='users')
op.drop_index('ix_users_first_name', table_name='users')
op.drop_index('ix_users_last_name', table_name='users')
op.drop_index('ix_users_timestamp_joined', table_name='users')
op.drop_table('users')
op.drop_index('ix_reviews_rating', table_name='reviews')
op.drop_index('ix_reviews_timestamp', table_name='reviews')
op.drop_table('reviews')
# ### end Alembic commands ###
def downgrade():
# ### commands auto generated by Alembic - please adjust! ###
op.create_table('reviews',
sa.Column('id', sa.INTEGER(), autoincrement=True, nullable=False),
sa.Column('user_id', sa.INTEGER(), autoincrement=False, nullable=True),
sa.Column('tutor_id', sa.INTEGER(), autoincrement=False, nullable=True),
sa.Column('rating', sa.INTEGER(), autoincrement=False, nullable=True),
sa.Column('timestamp', postgresql.TIMESTAMP(), autoincrement=False, nullable=True),
sa.ForeignKeyConstraint(['tutor_id'], ['tutors.id'], name='reviews_tutor_id_fkey'),
sa.ForeignKeyConstraint(['user_id'], ['users.id'], name='reviews_user_id_fkey'),
sa.PrimaryKeyConstraint('id', name='reviews_pkey')
)
op.create_index('ix_reviews_timestamp', 'reviews', ['timestamp'], unique=False)
op.create_index('ix_reviews_rating', 'reviews', ['rating'], unique=False)
op.create_table('users',
sa.Column('id', sa.INTEGER(), server_default=sa.text("nextval('users_id_seq'::regclass)"), autoincrement=True, nullable=False),
sa.Column('first_name', sa.VARCHAR(length=64), autoincrement=False, nullable=False),
sa.Column('last_name', sa.VARCHAR(length=64), autoincrement=False, nullable=False),
sa.Column('email', sa.VARCHAR(length=120), autoincrement=False, nullable=False),
sa.Column('profile_img', sa.VARCHAR(length=120), autoincrement=False, nullable=True),
sa.Column('password_hash', sa.VARCHAR(length=128), autoincrement=False, nullable=False),
sa.Column('timestamp_joined', postgresql.TIMESTAMP(), autoincrement=False, nullable=True),
sa.Column('about_me', sa.VARCHAR(length=140), autoincrement=False, nullable=True),
sa.Column('last_seen', postgresql.TIMESTAMP(timezone=True), autoincrement=False, nullable=True),
sa.PrimaryKeyConstraint('id', name='users_pkey'),
postgresql_ignore_search_path=False
)
op.create_index('ix_users_timestamp_joined', 'users', ['timestamp_joined'], unique=False)
op.create_index('ix_users_last_name', 'users', ['last_name'], unique=False)
op.create_index('ix_users_first_name', 'users', ['first_name'], unique=False)
op.create_index('ix_users_email', 'users', ['email'], unique=True)
op.create_table('categories',
sa.Column('id', sa.INTEGER(), server_default=sa.text("nextval('categories_id_seq'::regclass)"), autoincrement=True, nullable=False),
sa.Column('name', sa.VARCHAR(length=64), autoincrement=False, nullable=True),
sa.PrimaryKeyConstraint('id', name='categories_pkey'),
postgresql_ignore_search_path=False
)
op.create_index('ix_categories_name', 'categories', ['name'], unique=False)
op.create_table('tutors',
sa.Column('id', sa.INTEGER(), server_default=sa.text("nextval('tutors_id_seq'::regclass)"), autoincrement=True, nullable=False),
sa.Column('user_id', sa.INTEGER(), autoincrement=False, nullable=True),
sa.Column('price', postgresql.DOUBLE_PRECISION(precision=53), autoincrement=False, nullable=True),
sa.ForeignKeyConstraint(['user_id'], ['users.id'], name='tutors_user_id_fkey'),
sa.PrimaryKeyConstraint('id', name='tutors_pkey'),
postgresql_ignore_search_path=False
)
op.create_table('tutor_category',
sa.Column('tutor_id', sa.INTEGER(), autoincrement=False, nullable=False),
sa.Column('category_id', sa.INTEGER(), autoincrement=False, nullable=False),
sa.ForeignKeyConstraint(['category_id'], ['categories.id'], name='tutor_category_category_id_fkey'),
sa.ForeignKeyConstraint(['tutor_id'], ['tutors.id'], name='tutor_category_tutor_id_fkey'),
sa.PrimaryKeyConstraint('tutor_id', 'category_id', name='tutor_category_pkey')
)
# ### end Alembic commands ###
Models.py
class Users(UserMixin, db.Model):
__tablename__ = 'users'
id = db.Column(db.Integer, primary_key=True)
first_name = db.Column(db.String(64), index=True, nullable=False)
last_name = db.Column(db.String(64), index=True, nullable=False)
email = db.Column(db.String(120), index=True, unique=True, nullable=False)
profile_img = db.Column(db.String(120), nullable=True)
password_hash = db.Column(db.String(128), nullable=False)
timestamp_joined = db.Column(db.DateTime, index=True, default=datetime.utcnow)
about_me = db.Column(db.String(140), nullable=True)
last_seen = db.Column(db.DateTime(140), default=datetime.utcnow)
def set_password(self, password):
self.password_hash = generate_password_hash(password)
def check_password(self, password):
return check_password_hash(self.password_hash, password)
def avatar(self):
digest = md5(self.email.lower().encode('utf-8')).hexdigest()
return 'https://www.gravatar.com/avatar/{}?d=identicon'.format(
digest)
def __repr__(self):
return '<User {}>'.format(self.username)
class Tutors(db.Model):
__tablename__ = 'tutors'
id = db.Column(db.Integer, primary_key=True)
user_id = db.Column(db.Integer, db.ForeignKey('users.id'))
price = db.Column(db.Float)
# Connecting this field to the association table.
category = db.relationship("Categories", secondary="tutor_category")
def __repr__(self):
return '<Tutor id {}'.format(self.user_id) + ' , price {}>'.format(self.price)
class Reviews(db.Model):
__tablename__ = 'reviews'
id = db.Column(db.Integer, primary_key=True)
user_id = db.Column(db.Integer, db.ForeignKey('users.id'))
tutor_id = db.Column(db.Integer, db.ForeignKey('tutors.id'))
rating = db.Column(db.Integer, index=True)
timestamp = db.Column(db.DateTime, index=True, default=datetime.utcnow)
def __repr__(self):
return '<Review User: {}'.format(self.user_id) + ' Tutor: {}'.format(self.tutor_id) + ' Rating: {}>'.format(self.rating)
class Categories(db.Model):
__tablename__ = 'categories'
id = db.Column(db.Integer, primary_key=True)
name = db.Column(db.String(64), index=True)
# Connecting this field to the association table.
tutor = db.relationship('Tutors', secondary="tutor_category")
def __repr__(self):
return '<Category {}>'.format(self.name)
# Declaring the association table
tutor_category = db.Table('tutor_category',
db.Column('tutor_id', db.Integer, db.ForeignKey('tutors.id'), primary_key=True),
db.Column('category_id', db.Integer, db.ForeignKey('categories.id'), primary_key=True)
)
@login.user_loader
def load_user(id):
return Users.query.get(int(id))
Manage.py
from flask import Flask
from flask_script import Manager
from flask_migrate import Migrate, MigrateCommand
from flask_sqlalchemy import SQLAlchemy
from app import app
from app import models
db = SQLAlchemy(app)
POSTGRES = {
'user': 'richard',
'pw': 'richard2906',
'db': 'codetutors',
'host': 'localhost',
'port': '5432',
}
app.config['SQLALCHEMY_DATABASE_URI'] = 'postgresql://%(user)s:\
%(pw)s@%(host)s:%(port)s/%(db)s' % POSTGRES
app.config['SQLALCHEMY_TRACK_MODIFICATIONS'] = False
migrate = Migrate(app, db)
manager = Manager(app)
db.init_app(app)
manager.add_command('db', MigrateCommand)
def create_app():
app = Flask(__name__)
app.config['DEBUG'] = True
app.config['SQLALCHEMY_DATABASE_URI'] = 'postgresql://%(user)s:\
%(pw)s@%(host)s:%(port)s/%(db)s' % POSTGRES
app.config['SQLALCHEMY_TRACK_MODIFICATIONS'] = False
db = SQLAlchemy(app)
db.init_app(app)
return app
if __name__ == '__main__':
manager.run()
env.py
from __future__ import with_statement
import logging
from logging.config import fileConfig
from sqlalchemy import engine_from_config
from sqlalchemy import pool
from alembic import context
from manage import db
# 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)
logger = logging.getLogger('alembic.env')
# add your model's MetaData object here
# for 'autogenerate' support
# from app.models import Users, Tutors, Categories, Reviews
target_metadata = db.metadata
# from myapp import mymodel
# target_metadata = mymodel.Base.metadata
from flask import current_app
config.set_main_option(
'sqlalchemy.url',
str(current_app.extensions['migrate'].db.engine.url).replace('%', '%%'))
target_metadata = current_app.extensions['migrate'].db.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, target_metadata=target_metadata, literal_binds=True
)
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.
"""
# this callback is used to prevent an auto-migration from being generated
# when there are no changes to the schema
# reference: http://alembic.zzzcomputing.com/en/latest/cookbook.html
def process_revision_directives(context, revision, directives):
if getattr(config.cmd_opts, 'autogenerate', False):
script = directives[0]
if script.upgrade_ops.is_empty():
directives[:] = []
logger.info('No changes in schema detected.')
connectable = engine_from_config(
config.get_section(config.config_ini_section),
prefix='sqlalchemy.',
poolclass=pool.NullPool,
)
with connectable.connect() as connection:
context.configure(
connection=connection,
target_metadata=target_metadata,
process_revision_directives=process_revision_directives,
**current_app.extensions['migrate'].configure_args
)
with context.begin_transaction():
context.run_migrations()
if context.is_offline_mode():
run_migrations_offline()
else:
run_migrations_online()
感谢您的帮助
对于那些遇到类似问题的人，我使用 Flask-Script 管理器作为 'python manage.py db migrate'，然后更改为 'flask db migrate'，应用程序开始正确识别 Models/Tables。
我只是猜测，当您移至 flask db migrate 而不是将 flask_script 与 python3 migrate.py db migrate 一起使用时，您的数据库也发生了变化。
您的数据库（在您提出问题时）似乎已经包含您要迁移的表。当它们存在但不在您的代码中 used/mentioned/imported 时，显然 alembic 删除它们是正确的决定。
从这个角度来看，升级应该删除表，而降级会像以前一样重新创建它们。
始终在迁移脚本中导入模型（使用 flask_script 时）并始终使用 db upgrade 命令应用数据库更改，而不是自己添加表。
这应该会导致正确的升级脚本。
关于您的代码
- 您可以创建自己的
app而不是导入它 - 您使用了导入的
app变量来绑定 SQLAlchemy 实例，但您还定义了另一个未使用的create_app函数？你也在那个实例上做了一个db.init_app(app)（即使它是用SQLAlchemy(app) 创建的
我想这会导致 alembic 查看错误的 app 上下文，其中 none 定义了模型。另外，您的数据库包含此 app.
这是我的 migrate.py:
from flask import Flask
from flask_script import Manager
from flask_migrate import Migrate, MigrateCommand
from models import * # contains 'db.Model' classes and instance of 'db'
app = Flask(__name__)
config_path = "config.json"
app.config.from_json(config_path)
# db = SQLAlchemy(app) # <-- the "normal way"
db.init_app(app) # <-- most likely if you have defined 'db' already in 'models.py'
migrate = Migrate(app, db)
manager = Manager(app)
manager.add_command('db', MigrateCommand)
if __name__ == '__main__':
manager.run()