python - SQLAlchemy 的 Unicode 问题

Question

我知道我在从 Unicode 转换时遇到问题，但我不确定问题出在哪里。

我正在从 HTML 文件目录中提取有关最近欧洲之旅的数据。一些位置名称具有非 ASCII 字符(例如 é、ô、ü)。我正在使用正则表达式从文件的字符串表示中获取数据。

如果我打印我找到的位置，它们会打印字符，因此编码必须正确:

Le Pré-Saint-Gervais, France
Hôtel-de-Ville, France

我使用 SQLAlchemy 将数据存储在 SQLite 表中:

Base = declarative_base()
class Point(Base):
    __tablename__ = 'points'

    id = Column(Integer, primary_key=True)
    pdate = Column(Date)
    ptime = Column(Time)
    location = Column(Unicode(32))
    weather = Column(String(16))
    high = Column(Float)
    low = Column(Float)
    lat = Column(String(16))
    lon = Column(String(16))
    image = Column(String(64))
    caption = Column(String(64))

    def __init__(self, filename, pdate, ptime, location, weather, high, low, lat, lon, image, caption):
        self.filename = filename
        self.pdate = pdate
        self.ptime = ptime
        self.location = location
        self.weather = weather
        self.high = high
        self.low = low
        self.lat = lat
        self.lon = lon
        self.image = image
        self.caption = caption

    def __repr__(self):
        return "<Point('%s','%s','%s')>" % (self.filename, self.pdate, self.ptime)

engine = create_engine('sqlite:///:memory:', echo=False)
Base.metadata.create_all(engine)
Session = sessionmaker(bind = engine)
session = Session()

我遍历文件并将每个文件的数据插入数据库:

for filename in filelist:

    # open the file and extract the information using regex such as:
    location_re = re.compile("<h2>(.*)</h2>",re.M)
    # extract other data

    newpoint = Point(filename, pdate, ptime, location, weather, high, low, lat, lon, image, caption)
    session.add(newpoint)
    session.commit()

我在每次插入时都看到以下警告:

/usr/lib/python2.5/site-packages/SQLAlchemy-0.5.4p2-py2.5.egg/sqlalchemy/engine/default.py:230: SAWarning: Unicode type received non-unicode bind param value 'Spitalfields, United Kingdom'
  param.append(processors[key](compiled_params[key]))

当我尝试对表格执行任何操作时，例如:

session.query(Point).all()

我得到:

Traceback (most recent call last):
  File "./extract_trips.py", line 131, in <module>
    session.query(Point).all()
  File "/usr/lib/python2.5/site-packages/SQLAlchemy-0.5.4p2-py2.5.egg/sqlalchemy/orm/query.py", line 1193, in all
    return list(self)
  File "/usr/lib/python2.5/site-packages/SQLAlchemy-0.5.4p2-py2.5.egg/sqlalchemy/orm/query.py", line 1341, in instances
    fetch = cursor.fetchall()
  File "/usr/lib/python2.5/site-packages/SQLAlchemy-0.5.4p2-py2.5.egg/sqlalchemy/engine/base.py", line 1642, in fetchall
    self.connection._handle_dbapi_exception(e, None, None, self.cursor, self.context)
  File "/usr/lib/python2.5/site-packages/SQLAlchemy-0.5.4p2-py2.5.egg/sqlalchemy/engine/base.py", line 931, in _handle_dbapi_exception
    raise exc.DBAPIError.instance(statement, parameters, e, connection_invalidated=is_disconnect)
sqlalchemy.exc.OperationalError: (OperationalError) Could not decode to UTF-8 column 'points_location' with text 'Le Pré-Saint-Gervais, France' None None

我希望能够正确地存储并返回原始字符完整的位置名称。任何帮助将不胜感激。

Answer 1

我发现这篇文章在某种程度上帮助解释了我的麻烦:

http://www.amk.ca/python/howto/unicode#reading-and-writing-unicode-data

通过使用“编解码器”模块然后按如下方式更改我的程序，我能够获得所需的结果:

打开文件时:

infile = codecs.open(filename, 'r', encoding='iso-8859-1')

打印位置时:

print location.encode('ISO-8859-1')

我现在可以查询和操作表中的数据，而不会出现之前的错误。我只需要在输出文本时指定编码即可。

(我仍然不完全理解这是如何工作的，所以我想是时候了解更多关于 Python 的 unicode 处理的信息了...)