How do I test if int value exists in Python Enum without using try/catch?

Question

Using the Python Enum class, is there a way to test if an Enum contains a specific int value without using try/catch?

With the following class:

from enum import Enum  class Fruit(Enum):     Apple = 4     Orange = 5     Pear = 6 

How can I test for the value 6 (returning true), or the value 7 (returning false)?

Answer 1

test for values

variant 1

note that an Enum has a member called _value2member_map_ (which is undocumented and may be changed/removed in future python versions):

print(Fruit._value2member_map_) # {4: <Fruit.Apple: 4>, 5: <Fruit.Orange: 5>, 6: <Fruit.Pear: 6>} 

you can test if a value is in your Enum against this map:

5 in Fruit._value2member_map_  # True 7 in Fruit._value2member_map_  # False 

variant 2

if you do not want to rely on this feature this is an alternative:

values = [item.value for item in Fruit]  # [4, 5, 6] 

or (probably better): use a set; the in operator will be more efficient:

values = set(item.value for item in Fruit)  # {4, 5, 6} 

then test with

5 in values  # True 7 in values  # False 

add has_value to your class

you could then add this as a method to your class:

class Fruit(Enum):     Apple = 4     Orange = 5     Pear = 6      @classmethod     def has_value(cls, value):         return value in cls._value2member_map_   print(Fruit.has_value(5))  # True print(Fruit.has_value(7))  # False 

test for keys

if you want to test for the names (and not the values) i would use _member_names_:

'Apple' in Fruit._member_names_  # True 'Mango' in Fruit._member_names_  # False 

Answer 2

You could use Enum.__members__ - an ordered dictionary mapping names to members:

In [12]: 'Apple' in Fruit.__members__ Out[12]: True  In [13]: 'Grape' in Fruit.__members__ Out[13]: False