Question

我正在开发一个基于Flask和SQLAlchemy的网站

ss由sqlalchemy.orm中的sessionmaker创建
动漫，ActorQuote，AnimeComment是基于数据库结构的模型

```

@app.route('/page/<anime_name>', methods=['GET', 'POST'])
def show_page(anime_name):
    if request.method == 'GET':
        anime = ss.query(Anime).filter_by(anime_name=anime_name).first()
        actor_quotes = ss.query(ActorQuote).filter_by(anime_id=anime.id).all()
        anime_comments = ss.query(AnimeComment).filter_by(anime_id=anime.id).all()
        return render_template('page.html', anime=anime, actor_lines=actor_quotes, comments=anime_comments)

除了它之外，它会返回一个带有这些参数的页面 - 动漫，actor_quotes，anime_comments，它确实会抛出属性错误。

```

Traceback (most recent call last):
  File "/Library/Python/2.7/site-packages/flask/app.py", line 1836, in __call__
    return self.wsgi_app(environ, start_response)
  File "/Library/Python/2.7/site-packages/flask/app.py", line 1820, in wsgi_app
    response = self.make_response(self.handle_exception(e))
  File "/Library/Python/2.7/site-packages/flask/app.py", line 1403, in handle_exception
    reraise(exc_type, exc_value, tb)
  File "/Library/Python/2.7/site-packages/flask/app.py", line 1817, in wsgi_app
    response = self.full_dispatch_request()
  File "/Library/Python/2.7/site-packages/flask/app.py", line 1477, in full_dispatch_request
    rv = self.handle_user_exception(e)
  File "/Library/Python/2.7/site-packages/flask/app.py", line 1381, in handle_user_exception
    reraise(exc_type, exc_value, tb)
  File "/Library/Python/2.7/site-packages/flask/app.py", line 1475, in full_dispatch_request
    rv = self.dispatch_request()
  File "/Library/Python/2.7/site-packages/flask/app.py", line 1461, in dispatch_request
    return self.view_functions[rule.endpoint](**req.view_args)
  File "/Users/windrunner/hiacg/index.py", line 138, in show_page
    actor_lines = ss.query(ActorQuote).filter_by(anime_id=anime.id).all()
AttributeError: 'NoneType' object has no attribute 'id'

当我使用try-except来捕获错误时，它会抛出另一个UnboundLocalError。

```

try:
    anime = ss.query(Anime).filter_by(anime_name=anime_name).first()
    actor_quotes = ss.query(ActorQuote).filter_by(anime_id=anime.id).all()
    anime_comments = ss.query(AnimeComment).filter_by(anime_id=anime.id).all()
except AttibuteError:
    print 'AttibuteError occurs again!'

更奇怪的是，网站仍然运作良好，没有任何反复发生。

/page/化物语这会显示预期的页面而不会出现错误。
/page/剑风传奇这会按预期显示页面但有错误。

Answer 1

在你的行

anime = ss.query(Anime).filter_by(anime_name=anime_name).first()

变量anime如果找不到None（正如您在数据库中所说的那样），那么AttributeError在尝试访问None时就会id。anime = Anime.query.filter_by(anime_name=anime_name).first_or_404()

顺便说一句，我建议你使用Flask-SQLAlchemy扩展来解决所有数据库连接逻辑，并公开一些有用的函数，如`.first_or_404'。有了它，您的代码将成为

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基于Flask的网站中的奇怪AttributeError

1 个答案: