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|
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:
.. code:: python
import graphene
class Episode(graphene.Enum):
NEWHOPE = 4
EMPIRE = 5
JEDI = 6
But also using instances of Enum:
.. code:: python
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.
.. code:: python
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.
.. code:: python
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:
.. code:: python
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.
.. code:: python
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:
.. code:: python
from graphene import Enum
class Color(Enum):
RED = 1
GREEN = 2
BLUE = 3
assert Color.get(1) == Color.RED
.. |enum.Enum| replace:: ``enum.Enum``
.. _enum.Enum: https://docs.python.org/3/library/enum.html
|
