I have created the following Enum:
from enum import Enum class Action(str, Enum): NEW_CUSTOMER = "new_customer" LOGIN = "login" BLOCK = "block"
I have inherited from str
, too, so that I can do things such as:
action = "new_customer" ... if action == Action.NEW_CUSTOMER: ...
I would now like to be able to check if a string is in this Enum, such as:
if "new_customer" in Action: ....
I have tried adding the following method to the class:
def __contains__(self, item): return item in [i for i in self]
However, when I run this code:
print("new_customer" in [i for i in Action]) print("new_customer" in Action)
I get this exception:
True Traceback (most recent call last): File "/Users/kevinobrien/Documents/Projects/crazywall/utils.py", line 24, in <module> print("new_customer" in Action) File "/Library/Frameworks/Python.framework/Versions/3.8/lib/python3.8/enum.py", line 310, in __contains__ raise TypeError( TypeError: unsupported operand type(s) for 'in': 'str' and 'EnumMeta'
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Answer
I just bumped into this problem today (2020-12-09); I had to change a number of subpackages for Python 3.8.
Perhaps an alternative to the other solutions here is the following, inspired by the excellent answer here to a similar question, as well as @MadPhysicist’s answer on this page:
from enum import Enum, EnumMeta class MetaEnum(EnumMeta): def __contains__(cls, item): try: cls(item) except ValueError: return False return True class BaseEnum(Enum, metaclass=MetaEnum): pass class Stuff(BaseEnum): foo = 1 bar = 5
Tests (python >= 3.7
; tested up to 3.10):
>>> 1 in Stuff True >>> Stuff.foo in Stuff True >>> 2 in Stuff False >>> 2.3 in Stuff False >>> 'zero' in Stuff False