Flask Migrate - 遷移時出現 IndexError

Question

我正在使用帶有 SQLite3 的 Flask Migrate。 我有以下升級腳本：

from alembic import op
import sqlalchemy as sa


# revision identifiers, used by Alembic.
revision = 'e0b1170b3c02'
down_revision = '9fac07025424'
branch_labels = None
depends_on = None


def upgrade():
    # ### commands auto generated by Alembic - please adjust! ###
    with op.batch_alter_table('quiz_player', schema=None) as batch_op:
        batch_op.create_unique_constraint(batch_op.f('uq_quiz_player_player_id'), ['player_id'])
        batch_op.drop_constraint(None, type_='foreignkey')
        batch_op.create_foreign_key(batch_op.f('fk_quiz_player_session_id_quiz_session'), 'quiz_session', ['session_id'], ['session_id'])

    with op.batch_alter_table('quiz_session', schema=None) as batch_op:
        batch_op.create_unique_constraint(batch_op.f('uq_quiz_session_session_id'), ['session_id'])
        batch_op.create_unique_constraint(batch_op.f('uq_quiz_session_shortcode'), ['shortcode'])

    # ### end Alembic commands ###


def downgrade():
    # ### commands auto generated by Alembic - please adjust! ###
    with op.batch_alter_table('quiz_session', schema=None) as batch_op:
        batch_op.drop_constraint(batch_op.f('uq_quiz_session_shortcode'), type_='unique')
        batch_op.drop_constraint(batch_op.f('uq_quiz_session_session_id'), type_='unique')

    with op.batch_alter_table('quiz_player', schema=None) as batch_op:
        batch_op.drop_constraint(batch_op.f('fk_quiz_player_session_id_quiz_session'), type_='foreignkey')
        batch_op.create_foreign_key(None, 'quiz_session', ['session_id'], ['quiz_id'])
        batch_op.drop_constraint(batch_op.f('uq_quiz_player_player_id'), type_='unique')

    # ### end Alembic commands ###

我初始化數據庫如下：

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)
migrate = Migrate(app, db, render_as_batch = True)

運行遷移時出現以下錯誤：

Traceback (most recent call last):
  File "C:\Users\Henry\AppData\Local\Programs\Python\Python38-32\lib\runpy.py", line 193, in _run_module_as_main
    return _run_code(code, main_globals, None,
  File "C:\Users\Henry\AppData\Local\Programs\Python\Python38-32\lib\runpy.py", line 86, in _run_code
    exec(code, run_globals)
  File "C:\Users\Henry\Documents\Python\quiz\venv\Scripts\flask.exe\__main__.py", line 9, in <module>
  File "C:\Users\Henry\Documents\Python\quiz\venv\lib\site-packages\flask\cli.py", line 988, in main
    cli.main()
  File "C:\Users\Henry\Documents\Python\quiz\venv\lib\site-packages\flask\cli.py", line 579, in main
    return super().main(*args, **kwargs)
  File "C:\Users\Henry\Documents\Python\quiz\venv\lib\site-packages\click\core.py", line 1055, in main
    rv = self.invoke(ctx)
  File "C:\Users\Henry\Documents\Python\quiz\venv\lib\site-packages\click\core.py", line 1657, in invoke
    return _process_result(sub_ctx.command.invoke(sub_ctx))
  File "C:\Users\Henry\Documents\Python\quiz\venv\lib\site-packages\click\core.py", line 1657, in invoke
    return _process_result(sub_ctx.command.invoke(sub_ctx))
  File "C:\Users\Henry\Documents\Python\quiz\venv\lib\site-packages\click\core.py", line 1404, in invoke
    return ctx.invoke(self.callback, **ctx.params)
  File "C:\Users\Henry\Documents\Python\quiz\venv\lib\site-packages\click\core.py", line 760, in invoke
    return __callback(*args, **kwargs)
  File "C:\Users\Henry\Documents\Python\quiz\venv\lib\site-packages\click\decorators.py", line 26, in new_func
    return f(get_current_context(), *args, **kwargs)
  File "C:\Users\Henry\Documents\Python\quiz\venv\lib\site-packages\flask\cli.py", line 427, in decorator
    return __ctx.invoke(f, *args, **kwargs)
  File "C:\Users\Henry\Documents\Python\quiz\venv\lib\site-packages\click\core.py", line 760, in invoke
    return __callback(*args, **kwargs)
  File "C:\Users\Henry\Documents\Python\quiz\venv\lib\site-packages\flask_migrate\cli.py", line 149, in upgrade
    _upgrade(directory, revision, sql, tag, x_arg)
  File "C:\Users\Henry\Documents\Python\quiz\venv\lib\site-packages\flask_migrate\__init__.py", line 98, in wrapped
    f(*args, **kwargs)
  File "C:\Users\Henry\Documents\Python\quiz\venv\lib\site-packages\flask_migrate\__init__.py", line 185, in upgrade
    command.upgrade(config, revision, sql=sql, tag=tag)
  File "C:\Users\Henry\Documents\Python\quiz\venv\lib\site-packages\alembic\command.py", line 322, in upgrade
    script.run_env()
  File "C:\Users\Henry\Documents\Python\quiz\venv\lib\site-packages\alembic\script\base.py", line 569, in run_env
    util.load_python_file(self.dir, "env.py")
  File "C:\Users\Henry\Documents\Python\quiz\venv\lib\site-packages\alembic\util\pyfiles.py", line 94, in load_python_file
    module = load_module_py(module_id, path)
  File "C:\Users\Henry\Documents\Python\quiz\venv\lib\site-packages\alembic\util\pyfiles.py", line 110, in load_module_py
    spec.loader.exec_module(module)  # type: ignore
  File "<frozen importlib._bootstrap_external>", line 783, in exec_module
  File "<frozen importlib._bootstrap>", line 219, in _call_with_frames_removed
  File "migrations\env.py", line 91, in <module>
    run_migrations_online()
  File "migrations\env.py", line 85, in run_migrations_online
    context.run_migrations()
  File "<string>", line 8, in run_migrations
  File "C:\Users\Henry\Documents\Python\quiz\venv\lib\site-packages\alembic\runtime\environment.py", line 853, in run_migrations
    self.get_context().run_migrations(**kw)
  File "C:\Users\Henry\Documents\Python\quiz\venv\lib\site-packages\alembic\runtime\migration.py", line 623, in run_migrations
    step.migration_fn(**kw)
  File "C:\Users\Henry\Documents\Python\quiz\migrations\versions\e0b1170b3c02_.py", line 23, in upgrade
    batch_op.drop_constraint(None, type_='foreignkey')
  File "<string>", line 3, in drop_constraint
  File "C:\Users\Henry\Documents\Python\quiz\venv\lib\site-packages\alembic\operations\ops.py", line 244, in batch_drop_constraint
    return operations.invoke(op)
  File "C:\Users\Henry\Documents\Python\quiz\venv\lib\site-packages\alembic\operations\base.py", line 394, in invoke
    return fn(self, operation)
  File "C:\Users\Henry\Documents\Python\quiz\venv\lib\site-packages\alembic\operations\toimpl.py", line 185, in drop_constraint
    operations.schema_obj.generic_constraint(
  File "C:\Users\Henry\Documents\Python\quiz\venv\lib\site-packages\alembic\operations\schemaobj.py", line 182, in generic_constraint
    t.append_constraint(const)
  File "C:\Users\Henry\Documents\Python\quiz\venv\lib\site-packages\sqlalchemy\sql\schema.py", line 922, in append_constraint
    constraint._set_parent_with_dispatch(self)
  File "C:\Users\Henry\Documents\Python\quiz\venv\lib\site-packages\sqlalchemy\sql\base.py", line 1047, in _set_parent_with_dispatch
    self.dispatch.after_parent_attach(self, parent)
  File "C:\Users\Henry\Documents\Python\quiz\venv\lib\site-packages\sqlalchemy\event\attr.py", line 256, in __call__
    fn(*args, **kw)
  File "C:\Users\Henry\Documents\Python\quiz\venv\lib\site-packages\sqlalchemy\sql\naming.py", line 208, in _constraint_name
    newname = _constraint_name_for_table(const, table)
  File "C:\Users\Henry\Documents\Python\quiz\venv\lib\site-packages\sqlalchemy\sql\naming.py", line 166, in _constraint_name_for_table
    convention
  File "C:\Users\Henry\Documents\Python\quiz\venv\lib\site-packages\sqlalchemy\sql\naming.py", line 101, in __getitem__
    return getattr(self, "_key_%s" % key)()
  File "C:\Users\Henry\Documents\Python\quiz\venv\lib\site-packages\sqlalchemy\sql\naming.py", line 82, in _key_referred_table_name
    fk = self.const.elements[0]
IndexError: list index out of range

我試圖將我的QuizPlayer模型中的 session_id = db.Column(db.Integer, session_id = db.Column(db.Integer, db.ForeignKey("quiz_session.quiz_id"))更改為session_id = db.Column(db.Integer, db.ForeignKey("quiz_session.session_id")) 。 遷移出錯，因為我沒有使用批處理模式。 我添加了render_as_batch = True但由於未命名的約束，遷移失敗了。 我按照其他答案中的建議添加了一個命名約定，現在我遇到了這個錯誤，可能是由命名約定引起的。 這個模型是在添加命名約定和啟用批處理模式之前創建的，這就是我認為它不起作用的原因。

Answer 1

我注釋掉了

batch_op.drop_constraint(None, type_='foreignkey')

這似乎解決了它。