fix: workaround db migration error when adding custom_disclaimer column to recommended_apps

[bowenliang123]

Description

• the failing migration script was introduced in Feat/chat custom disclaimer #4306
• error when running flask db upgrade for db migration

root@5789a1154494:/app/api# flask db upgrade

None of PyTorch, TensorFlow >= 2.0, or Flax have been found. Models won't be available and only tokenizers, configuration and file/data utilities can be used.
Traceback (most recent call last):
  File "/usr/local/lib/python3.10/site-packages/sqlalchemy/engine/base.py", line 1967, in _exec_single_context
    self.dialect.do_execute(
  File "/usr/local/lib/python3.10/site-packages/sqlalchemy/engine/default.py", line 924, in do_execute
    cursor.execute(statement, parameters)
psycopg2.errors.NotNullViolation: column "custom_disclaimer" of relation "recommended_apps" contains null values


The above exception was the direct cause of the following exception:

Traceback (most recent call last):
  File "/usr/local/bin/flask", line 8, in <module>
    sys.exit(main())
  File "/usr/local/lib/python3.10/site-packages/flask/cli.py", line 1105, in main
    cli.main()
  File "/usr/local/lib/python3.10/site-packages/click/core.py", line 1078, in main
    rv = self.invoke(ctx)
  File "/usr/local/lib/python3.10/site-packages/click/core.py", line 1688, in invoke
    return _process_result(sub_ctx.command.invoke(sub_ctx))
  File "/usr/local/lib/python3.10/site-packages/click/core.py", line 1688, in invoke
    return _process_result(sub_ctx.command.invoke(sub_ctx))
  File "/usr/local/lib/python3.10/site-packages/click/core.py", line 1434, in invoke
    return ctx.invoke(self.callback, **ctx.params)
  File "/usr/local/lib/python3.10/site-packages/click/core.py", line 783, in invoke
    return __callback(*args, **kwargs)
  File "/usr/local/lib/python3.10/site-packages/click/decorators.py", line 33, in new_func
    return f(get_current_context(), *args, **kwargs)
  File "/usr/local/lib/python3.10/site-packages/flask/cli.py", line 386, in decorator
    return ctx.invoke(f, *args, **kwargs)
  File "/usr/local/lib/python3.10/site-packages/click/core.py", line 783, in invoke
    return __callback(*args, **kwargs)
  File "/usr/local/lib/python3.10/site-packages/flask_migrate/cli.py", line 154, in upgrade
    _upgrade(directory, revision, sql, tag, x_arg)
  File "/usr/local/lib/python3.10/site-packages/flask_migrate/__init__.py", line 111, in wrapped
    f(*args, **kwargs)
  File "/usr/local/lib/python3.10/site-packages/flask_migrate/__init__.py", line 200, in upgrade
    command.upgrade(config, revision, sql=sql, tag=tag)
  File "/usr/local/lib/python3.10/site-packages/alembic/command.py", line 403, in upgrade
    script.run_env()
  File "/usr/local/lib/python3.10/site-packages/alembic/script/base.py", line 583, in run_env
    util.load_python_file(self.dir, "env.py")
  File "/usr/local/lib/python3.10/site-packages/alembic/util/pyfiles.py", line 95, in load_python_file
    module = load_module_py(module_id, path)
  File "/usr/local/lib/python3.10/site-packages/alembic/util/pyfiles.py", line 113, in load_module_py
    spec.loader.exec_module(module)  # type: ignore
  File "<frozen importlib._bootstrap_external>", line 883, in exec_module
  File "<frozen importlib._bootstrap>", line 241, in _call_with_frames_removed
  File "/app/api/migrations/env.py", line 112, in <module>
    run_migrations_online()
  File "/app/api/migrations/env.py", line 106, in run_migrations_online
    context.run_migrations()
  File "<string>", line 8, in run_migrations
  File "/usr/local/lib/python3.10/site-packages/alembic/runtime/environment.py", line 948, in run_migrations
    self.get_context().run_migrations(**kw)
  File "/usr/local/lib/python3.10/site-packages/alembic/runtime/migration.py", line 627, in run_migrations
    step.migration_fn(**kw)
  File "/app/api/migrations/versions/5fda94355fce_custom_disclaimer.py", line 22, in upgrade
    with op.batch_alter_table('recommended_apps', schema=None) as batch_op:
  File "/usr/local/lib/python3.10/contextlib.py", line 142, in __exit__
    next(self.gen)
  File "/usr/local/lib/python3.10/site-packages/alembic/operations/base.py", line 398, in batch_alter_table
    impl.flush()
  File "/usr/local/lib/python3.10/site-packages/alembic/operations/batch.py", line 116, in flush
    fn(*arg, **kw)
  File "/usr/local/lib/python3.10/site-packages/alembic/ddl/impl.py", line 334, in add_column
    self._exec(base.AddColumn(table_name, column, schema=schema))
  File "/usr/local/lib/python3.10/site-packages/alembic/ddl/impl.py", line 207, in _exec
    return conn.execute(construct, multiparams)
  File "/usr/local/lib/python3.10/site-packages/sqlalchemy/engine/base.py", line 1418, in execute
    return meth(
  File "/usr/local/lib/python3.10/site-packages/sqlalchemy/sql/ddl.py", line 180, in _execute_on_connection
    return connection._execute_ddl(
  File "/usr/local/lib/python3.10/site-packages/sqlalchemy/engine/base.py", line 1529, in _execute_ddl
    ret = self._execute_context(
  File "/usr/local/lib/python3.10/site-packages/sqlalchemy/engine/base.py", line 1846, in _execute_context
    return self._exec_single_context(
  File "/usr/local/lib/python3.10/site-packages/sqlalchemy/engine/base.py", line 1986, in _exec_single_context
    self._handle_dbapi_exception(
  File "/usr/local/lib/python3.10/site-packages/sqlalchemy/engine/base.py", line 2353, in _handle_dbapi_exception
    raise sqlalchemy_exception.with_traceback(exc_info[2]) from e
  File "/usr/local/lib/python3.10/site-packages/sqlalchemy/engine/base.py", line 1967, in _exec_single_context
    self.dialect.do_execute(
  File "/usr/local/lib/python3.10/site-packages/sqlalchemy/engine/default.py", line 924, in do_execute
    cursor.execute(statement, parameters)
sqlalchemy.exc.IntegrityError: (psycopg2.errors.NotNullViolation) column "custom_disclaimer" of relation "recommended_apps" contains null values

[SQL: ALTER TABLE recommended_apps ADD COLUMN custom_disclaimer VARCHAR(255) NOT NULL]

Type of Change

Please delete options that are not relevant.

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)
• This change requires a documentation update, included: Dify Document
• Improvement, including but not limited to code refactoring, performance optimization, and UI/UX improvement
• Dependency upgrade

How Has This Been Tested?

Please describe the tests that you ran to verify your changes. Provide instructions so we can reproduce. Please also list any relevant details for your test configuration

• TODO

Suggested Checklist:

• I have performed a self-review of my own code
• I have commented my code, particularly in hard-to-understand areas
• My changes generate no new warnings
• I ran dev/reformat(backend) and cd web && npx lint-staged(frontend) to appease the lint gods
• optional I have made corresponding changes to the documentation
• optional I have added tests that prove my fix is effective or that my feature works
• optional New and existing unit tests pass locally with my changes

[bowenliang123]

Or is there any better solution or suggestion from @patryk20120 , as the author of #4306 ?

[takatost]

LGTM

[bowenliang123]

Thanks~

[patryk20120]

My bad, but fask lied to me running the migration successfully 😸