Flask sqlArchemy, html: ValueError: no enough values to unpack (expected 2, got 1)

Question

我正在执行命令 flask migrate 在它开始运行时创建更多引用表，即使它识别了表，它也会引发以下错误。我通常很容易寻找和发现错误，但在这种情况下我不能轻易识别它。

PDT：我是编程主题的新手，感谢您的理解和时间。

主要是我需要知道错误在哪里才能纠正它，但它在这里调用的扩展并不引用我写的任何东西。谢谢

INFO  [alembic.autogenerate.compare] Detected added column 'blog_user.youtube'
Traceback (most recent call last):
  File "c:\users\user\appdata\local\programs\python\python38-32\lib\runpy.py", line 194, in _run_module_as_main
    return _run_code(code, main_globals, None,
  File "c:\users\user\appdata\local\programs\python\python38-32\lib\runpy.py", line 87, in _run_code
    exec(code, run_globals)

  File "C:\Users\user\Desktop\LLAC\env\Scripts\flask.exe\__main__.py", line 7, in <module>
  File "c:\users\user\desktop\llac\env\lib\site-packages\flask\cli.py", line 967, in main
    cli.main(args=sys.argv[1:], prog_name="python -m flask" if as_module else None)

  File "c:\users\user\desktop\llac\env\lib\site-packages\flask\cli.py", line 586, in main
    return super(FlaskGroup, self).main(*args, **kwargs)

  File "c:\users\user\desktop\llac\env\lib\site-packages\click\core.py", line 782, in main
    rv = self.invoke(ctx)

  File "c:\users\user\desktop\llac\env\lib\site-packages\click\core.py", line 1259, in invoke
    return _process_result(sub_ctx.command.invoke(sub_ctx))

  File "c:\users\user\desktop\llac\env\lib\site-packages\click\core.py", line 1259, in invoke
    return _process_result(sub_ctx.command.invoke(sub_ctx))

  File "c:\users\user\desktop\llac\env\lib\site-packages\click\core.py", line 1066, in invoke
    return ctx.invoke(self.callback, **ctx.params)

  File "c:\users\user\desktop\llac\env\lib\site-packages\click\core.py", line 610, in invoke
    return callback(*args, **kwargs)

  File "c:\users\user\desktop\llac\env\lib\site-packages\click\decorators.py", line 21, in new_func
    return f(get_current_context(), *args, **kwargs)

  File "c:\users\user\desktop\llac\env\lib\site-packages\flask\cli.py", line 426, in decorator
    return __ctx.invoke(f, *args, **kwargs)

  File "c:\users\user\desktop\llac\env\lib\site-packages\click\core.py", line 610, in invoke
    return callback(*args, **kwargs)

  File "c:\users\user\desktop\llac\env\lib\site-packages\flask_migrate\cli.py", line 89, in migrate
    _migrate(directory, message, sql, head, splice, branch_label, version_path,

  File "c:\users\user\desktop\llac\env\lib\site-packages\flask_migrate\__init__.py", line 96, in wrapped
    f(*args, **kwargs)
  File "c:\users\user\desktop\llac\env\lib\site-packages\flask_migrate\__init__.py", line 210, in migrate
    command.revision(config, message, autogenerate=True, sql=sql,

  File "c:\users\user\desktop\llac\env\lib\site-packages\alembic\command.py", line 221, in revision
    scripts = [script for script in revision_context.generate_scripts()]

  File "c:\users\user\desktop\llac\env\lib\site-packages\alembic\command.py", line 221, in <listcomp>
    scripts = [script for script in revision_context.generate_scripts()]

  File "c:\users\user\desktop\llac\env\lib\site-packages\alembic\autogenerate\api.py", line 513, in generate_scripts
    yield self._to_script(generated_revision)

  File "c:\users\user\desktop\llac\env\lib\site-packages\alembic\autogenerate\api.py", line 425, in _to_script
    render._render_python_into_templatevars(

  File "c:\users\user\desktop\llac\env\lib\site-packages\alembic\autogenerate\render.py", line 49, in _render_python_into_templatevars
    _render_cmd_body(upgrade_ops, autogen_context)

  File "c:\users\user\desktop\llac\env\lib\site-packages\alembic\autogenerate\render.py", line 71, in _render_cmd_body
    lines = render_op(autogen_context, op)

  File "c:\users\user\desktop\llac\env\lib\site-packages\alembic\autogenerate\render.py", line 87, in render_op
    lines = util.to_list(renderer(autogen_context, op))

  File "c:\users\user\desktop\llac\env\lib\site-packages\alembic\autogenerate\render.py", line 179, in _add_table
    for rcons in [

  File "c:\users\user\desktop\llac\env\lib\site-packages\alembic\autogenerate\render.py", line 180, in <listcomp>
    _render_constraint(cons, autogen_context)

  File "c:\users\user\desktop\llac\env\lib\site-packages\alembic\autogenerate\render.py", line 775, in _render_constraint
    return renderer(constraint, autogen_context)

  File "c:\users\user\desktop\llac\env\lib\site-packages\alembic\autogenerate\render.py", line 871, in _render_foreign_key
    "refcols": ", ".join(

  File "c:\users\user\desktop\llac\env\lib\site-packages\alembic\autogenerate\render.py", line 872, in <genexpr>
    repr(_fk_colspec(f, apply_metadata_schema))

  File "c:\users\user\desktop\llac\env\lib\site-packages\alembic\autogenerate\render.py", line 808, in _fk_colspec
    tname, colname = tokens[-2:]

ValueError: not enough values to unpack (expected 2, got 1)

Answer 1

我遇到了同样的错误。在我的情况下，如果我删除 table_args ，错误就会消失。然后迁移工作，所以我认为它可能与 ForeignKey 约束有关。

class AccommodationAirport(db.Model):
    __tablename__ = 'accommodation_airport'
    __table_args__ = (
        ForeignKeyConstraint(
        ['supplier'], ['accommodation'],
        name='fk_acco_airp_sup_acco'
        ),
        UniqueConstraint(
            'supplier', 'accommodation', 'airport',
            name='uq_sup_acco_airp'
        )
    )
    created = db.Column(db.DateTime, server_default=func.now())
    last_modified = db.Column(db.DateTime, onupdate=func.now())
    modified_by = db.Column(db.Integer)
    supplier = db.Column(db.String(8), primary_key=True)
    accommodation = db.Column(db.String(32), primary_key=True)
    airport = db.Column(db.String(3), primary_key=True)
    

目前我找到的唯一解决方案是

1. 用约束声明注释掉 table_args，
2. 迁移 -> 升级
3. 取消对 table_args 的注释
4. 迁移 -> 升级