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