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

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)?

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

There is a way to have all the enums be able to check if an item is present:

import enum 

class MyEnumMeta(enum.EnumMeta): 
    def __contains__(cls, item): 
        return item in [v.value for v in cls.__members__.values()] 

class MyEnum(enum.Enum, metaclass=MyEnumMeta): 
   FOO = "foo" 
   BAR = "bar"

Now you can do an easy check:

>>> "foo" in MyEnum
True

It can even be made simpler if all the enum's values will always be the same type -- for example strings:

import enum 
 
class MyEnumMeta(enum.EnumMeta):  
    def __contains__(cls, item): 
        return item in cls.__members__.values()

class MyEnum(str, enum.Enum, metaclass=MyEnumMeta): 
    FOO = "foo" 
    BAR = "bar"

Edit: Yet another version, technically the most correct one:

import enum 

class MyEnumMeta(enum.EnumMeta): 
    def __contains__(cls, item): 
        try:
            cls(item)
        except ValueError:
            return False
        else:
            return True

class MyEnum(enum.Enum, metaclass=MyEnumMeta): 
   FOO = "foo" 
   BAR = "bar"

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

Building on what Reda Maachi started:

6 in Fruit.__members__.values() 

returns True

7 in Fruit.__members__.values()  

returns False

If the enum has many members, this approach can be faster because it doesn't make a new list and stops walking the enum when the given value is found:

any(x.value == 5 for x in Fruit)  # True
any(x.value == 7 for x in Fruit)  # False