python eval() 进行条件匹配

最近开发一个功能，根据条件表达式过滤数据，其中用到了eval（条件字符串，字典）

发现一个现象：

>>> print u"campGrade in [ 'u51cfu8102u8425u6559u7ec3u4f53u9a8cu73ed', ]"
campGrade in [ '减脂体验班', ]

>>> print {'campGrade':u'u51cfu8102u8425u6559u7ec3u4f53u9a8cu73ed'}
{'campGrade': u'u51cfu8102u8425u6559u7ec3u4f53u9a8cu73ed'}

>>> print u'u51cfu8102u8425u6559u7ec3u4f53u9a8cu73ed'
减脂体验班

此时，若直接判断，会返回 False

>>> eval(u"campGrade in [ 'u51cfu8102u8425u6559u7ec3u4f53u9a8cu73ed', ]", {'campGrade':u'u51cfu8102u8425u6559u7ec3u4f53u9a8cu73ed'})
<string>:1: UnicodeWarning: Unicode equal comparison failed to convert both arguments to Unicode - interpreting them as being unequal
False

字典中的unicode 需要转化成 str，如下：

>>> eval(u"campGrade in [ 'u51cfu8102u8425u6559u7ec3u4f53u9a8cu73ed', ]", {'campGrade':'减脂体验班'})
True

代码中可以添加.encode("utf-8")，将unocode转换成str形式！

>>> eval(u"campGrade in [ 'u51cfu8102u8425u6559u7ec3u4f53u9a8cu73ed', ]", {'campGrade':u'u51cfu8102u8425u6559u7ec3u4f53u9a8cu73ed'.encode("utf-8")})
True