在Python中将字符串转换为Enum

我想知道将字符串转换（反序列化）为Python的Enum类的正确方法是什么。似乎可以getattr(YourEnumType, str)完成这项工作，但是我不确定它是否足够安全。

更具体地说，我想像这样将'debug'字符串转换为Enum对象：

class BuildType(Enum):
    debug = 200
    release = 400

此功能已内置到枚举[1]中：

>>> from enum import Enum
>>> class Build(Enum):
...   debug = 200
...   build = 400
... 
>>> Build['debug']
<Build.debug: 200>

[1]官方文档： Enum programmatic access

另一种选择（如果你的字符串不映射1-1到您的枚举的情况下特别有用）是一个添加staticmethod到您的Enum，如：

class QuestionType(enum.Enum):
    MULTI_SELECT = "multi"
    SINGLE_SELECT = "single"

    @staticmethod
    def from_str(label):
        if label in ('single', 'singleSelect'):
            return QuestionType.SINGLE_SELECT
        elif label in ('multi', 'multiSelect'):
            return QuestionType.MULTI_SELECT
        else:
            raise NotImplementedError

那你可以做 question_type = QuestionType.from_str('singleSelect')

def custom_enum(typename, items_dict):
    class_definition = """
from enum import Enum

class {}(Enum):
    {}""".format(typename, '\n    '.join(['{} = {}'.format(k, v) for k, v in items_dict.items()]))

    namespace = dict(__name__='enum_%s' % typename)
    exec(class_definition, namespace)
    result = namespace[typename]
    result._source = class_definition
    return result

MyEnum = custom_enum('MyEnum', {'a': 123, 'b': 321})
print(MyEnum.a, MyEnum.b)

还是需要将字符串转换为已知的 Enum？

class MyEnum(Enum):
    a = 'aaa'
    b = 123

print(MyEnum('aaa'), MyEnum(123))

要么：

class BuildType(Enum):
    debug = 200
    release = 400

print(BuildType.__dict__['debug'])

print(eval('BuildType.debug'))
print(type(eval('BuildType.debug')))    
print(eval(BuildType.__name__ + '.debug'))  # for work with code refactoring

我的类Java解决方案。希望它可以帮助某人...

    from enum import Enum, auto


    class SignInMethod(Enum):
        EMAIL = auto(),
        GOOGLE = auto()

        @staticmethod
        def value_of(value) -> Enum:
            for m, mm in SignInMethod.__members__.items():
                if m == value.upper():
                    return mm


    sim = SignInMethod.value_of('EMAIL')
    print("""TEST
    1). {0}
    2). {1}
    3). {2}
    """.format(sim, sim.name, isinstance(sim, SignInMethod)))

对@rogueleaderr答案的改进：

class QuestionType(enum.Enum):
    MULTI_SELECT = "multi"
    SINGLE_SELECT = "single"

    @classmethod
    def from_str(cls, label):
        if label in ('single', 'singleSelect'):
            return cls.SINGLE_SELECT
        elif label in ('multi', 'multiSelect'):
            return cls.MULTI_SELECT
        else:
            raise NotImplementedError

我只想通知这在python 3.6中不起作用

class MyEnum(Enum):
    a = 'aaa'
    b = 123

print(MyEnum('aaa'), MyEnum(123))

您将不得不像这样以元组形式提供数据

MyEnum(('aaa',))

编辑：这被证明是错误的。感谢指出我的错误的评论者