Enums¶
An Enum is a special GraphQL type that represents a set of
symbolic names (members) bound to unique, constant values.
Definition¶
You can create an Enum using classes:
import graphene
class Episode(graphene.Enum):
NEWHOPE = 4
EMPIRE = 5
JEDI = 6
But also using instances of Enum:
Episode = graphene.Enum('Episode', [('NEWHOPE', 4), ('EMPIRE', 5), ('JEDI', 6)])
Value descriptions¶
It’s possible to add a description to an enum value, for that the enum value
needs to have the description property on it.
class Episode(graphene.Enum):
NEWHOPE = 4
EMPIRE = 5
JEDI = 6
@property
def description(self):
if self == Episode.NEWHOPE:
return 'New Hope Episode'
return 'Other episode'
Usage with Python Enums¶
In case the Enums are already defined it’s possible to reuse them using
the Enum.from_enum function.
graphene.Enum.from_enum(AlreadyExistingPyEnum)
Enum.from_enum supports a description and deprecation_reason lambdas as input so
you can add description etc. to your enum without changing the original:
graphene.Enum.from_enum(
AlreadyExistingPyEnum,
description=lambda v: return 'foo' if v == AlreadyExistingPyEnum.Foo else 'bar'
)
Notes¶
graphene.Enum uses enum.Enum internally (or a backport if
that’s not available) and can be used in a similar way, with the exception of
member getters.
In the Python Enum implementation you can access a member by initing the Enum.
from enum import Enum
class Color(Enum):
RED = 1
GREEN = 2
BLUE = 3
assert Color(1) == Color.RED
However, in Graphene Enum you need to call get to have the same effect:
from graphene import Enum
class Color(Enum):
RED = 1
GREEN = 2
BLUE = 3
assert Color.get(1) == Color.RED