flask - 烧瓶迁移“ValueError:约束必须有一个名称”
问题描述
我创建了一个烧瓶迁移脚本,但是,当我运行升级功能时,出现以下错误:
INFO [alembic.runtime.migration] Context impl SQLiteImpl.
INFO [alembic.runtime.migration] Will assume non-transactional DDL.
INFO [alembic.runtime.migration] Running upgrade -> 6378428b838a, empty message
Traceback (most recent call last):
File "migrate.py", line 22, in <module>
manager.run()
File "/Users/slatifi/git/StaffTrainingLog/venv/lib/python3.7/site-packages/flask_script/__init__.py", line 417, in run
result = self.handle(argv[0], argv[1:])
File "/Users/slatifi/git/StaffTrainingLog/venv/lib/python3.7/site-packages/flask_script/__init__.py", line 386, in handle
res = handle(*args, **config)
File "/Users/slatifi/git/StaffTrainingLog/venv/lib/python3.7/site-packages/flask_script/commands.py", line 216, in __call__
return self.run(*args, **kwargs)
File "/Users/slatifi/git/StaffTrainingLog/venv/lib/python3.7/site-packages/flask_migrate/__init__.py", line 95, in wrapped
f(*args, **kwargs)
File "/Users/slatifi/git/StaffTrainingLog/venv/lib/python3.7/site-packages/flask_migrate/__init__.py", line 280, in upgrade
command.upgrade(config, revision, sql=sql, tag=tag)
File "/Users/slatifi/git/StaffTrainingLog/venv/lib/python3.7/site-packages/alembic/command.py", line 298, in upgrade
script.run_env()
File "/Users/slatifi/git/StaffTrainingLog/venv/lib/python3.7/site-packages/alembic/script/base.py", line 489, in run_env
util.load_python_file(self.dir, "env.py")
File "/Users/slatifi/git/StaffTrainingLog/venv/lib/python3.7/site-packages/alembic/util/pyfiles.py", line 98, in load_python_file
module = load_module_py(module_id, path)
File "/Users/slatifi/git/StaffTrainingLog/venv/lib/python3.7/site-packages/alembic/util/compat.py", line 173, in load_module_py
spec.loader.exec_module(module)
File "<frozen importlib._bootstrap_external>", line 728, in exec_module
File "<frozen importlib._bootstrap>", line 219, in _call_with_frames_removed
File "migrations/env.py", line 96, in <module>
run_migrations_online()
File "migrations/env.py", line 90, in run_migrations_online
context.run_migrations()
File "<string>", line 8, in run_migrations
File "/Users/slatifi/git/StaffTrainingLog/venv/lib/python3.7/site-packages/alembic/runtime/environment.py", line 846, in run_migrations
self.get_context().run_migrations(**kw)
File "/Users/slatifi/git/StaffTrainingLog/venv/lib/python3.7/site-packages/alembic/runtime/migration.py", line 518, in run_migrations
step.migration_fn(**kw)
File "/Users/slatifi/git/StaffTrainingLog/migrations/versions/6378428b838a_.py", line 23, in upgrade
batch_op.create_foreign_key(None, 'organisation', ['organisation'], ['id'])
File "/Library/Developer/CommandLineTools/Library/Frameworks/Python3.framework/Versions/3.7/lib/python3.7/contextlib.py", line 119, in __exit__
next(self.gen)
File "/Users/slatifi/git/StaffTrainingLog/venv/lib/python3.7/site-packages/alembic/operations/base.py", line 325, in batch_alter_table
impl.flush()
File "/Users/slatifi/git/StaffTrainingLog/venv/lib/python3.7/site-packages/alembic/operations/batch.py", line 106, in flush
fn(*arg, **kw)
File "/Users/slatifi/git/StaffTrainingLog/venv/lib/python3.7/site-packages/alembic/operations/batch.py", line 390, in add_constraint
raise ValueError("Constraint must have a name")
ValueError: Constraint must have a name
我见过其他人有同样的错误,他们只是将 render_as_batch 添加到 env.py 文件中。我这样做了,但我仍然得到同样的错误。有什么想法吗?
注意:这是我在 env.py 文件中所做的修改:
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,
render_as_batch=True
)
这是迁移创建的升级脚本
from alembic import op
import sqlalchemy as sa
# revision identifiers, used by Alembic.
revision = '2838e3e96536'
down_revision = None
branch_labels = None
depends_on = None
def upgrade():
# ### commands auto generated by Alembic - please adjust! ###
with op.batch_alter_table('user', schema=None) as batch_op:
batch_op.add_column(sa.Column('organisation', sa.String(length=5), nullable=False))
batch_op.create_foreign_key(None, 'organisation', ['organisation'], ['id'])
# ### end Alembic commands ###
def downgrade():
# ### commands auto generated by Alembic - please adjust! ###
with op.batch_alter_table('user', schema=None) as batch_op:
batch_op.drop_constraint(None, type_='foreignkey')
batch_op.drop_column('organisation')
# ### en
d Alembic 命令###
解决方案
这是正常的,因为 SQLite3 不支持 ALTER 表。
您可以render_as_batch=True
像这样在 Flask-Migrate 的实例化过程中传递:
migrate = Migrate(app,db,render_as_batch=True)
不需要修改env
Flask-Migrate 的文件。
此外,为了完全避免未来迁移的问题,您可以为 SQLAlchemy 元数据的所有类型的约束创建一个约束命名模板,然后我认为您将获得一致的名称。
在Flask-SQLAlchemy文档中查看如何执行此操作。为了您的方便,我从下面的文档中复制了代码示例:
from sqlalchemy import MetaData
from flask import Flask
from flask_sqlalchemy import SQLAlchemy
convention = {
"ix": 'ix_%(column_0_label)s',
"uq": "uq_%(table_name)s_%(column_0_name)s",
"ck": "ck_%(table_name)s_%(constraint_name)s",
"fk": "fk_%(table_name)s_%(column_0_name)s_%(referred_table_name)s",
"pk": "pk_%(table_name)s"
}
metadata = MetaData(naming_convention=convention)
db = SQLAlchemy(app, metadata=metadata)
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