如何将单个枚举用于 django 模型和 graphql 突变参数？

Question

我已经定义了 Django 模型，其字段包含对应于枚举的文本选择。 GraphQL API 提供了带有 enum 类型参数的突变（不是直接从模型派生的），它应该只接受与模型相同的值。我怎样才能摆脱我的重复？

models.py：

class SomeModel(models.Model):

    class SomeEnum(models.TextChoices):

        A = "A", _("Option A")
        B = "B", _("Option B")

    enum_field = models.CharField(
        max_length=1,
        choices=SomeEnum.choices,
        default=SomeEnum.A,
    )

schema.py：

class SomeEnumSchema(graphene.Enum):

    A = "A"
    B = "B"


class SomeMutation(graphene.Mutation):

    class Arguments:
        some_enum = SomeEnumSchema(required=True)

Answer 1

使用以下类扩展您的 graphene.Enum 实例

from inspect import getmembers, isroutine

class EnumChoices:
    @classmethod
    def choices(self):
        attributes = getmembers(self, lambda a: not (isroutine(a)))
        values = [(a[0], a[1]._value_) for a in attributes if hasattr(a[1], "_value_")]
        return values

您的示例枚举将如下所示

# import the EnumChoices class above 
from graphene import Enum

class YourExampleChoices(EnumChoices, Enum):
    BAD = "Bad"
    MEH = "Meh"
    NORMAL = "Normal"
    LIKE = "Like"
    LOVE = "Love"

您的示例 graphene.types.InputObjectType 将如下所示

# import the YourExampleChoices class above
from graphene.types import InputObjectType

class YourExampleChoicesMutationInput(InputObjectType):
    choice = YourExampleChoices(required=True)

您的示例 graphene.Mutation 将如下所示

# import the YourExampleChoicesMutationInput class above 
import graphene

from graphene.types.mutation import Mutation

class YourExampleMutation(Mutation):
    # make sure to define your mutation results fields

    class Arguments:
        input = YourExampleChoicesMutationInput(required=True)

    def mutate(root, info, input):
        # what do you want this mutation to do?
        pass

您的 Django 模型将如下所示

# import the YourExampleChoices class above
# notice that `YourExampleChoices.choices()` is callable, this is slightly different from the `Textchoices.choices` which isn't callable

class YourExampleModel(TimestampBase):
    choices = models.CharField(
        max_length=6, 
        choices=YourExampleChoices.choices(), 
        default=YourExampleChoices.NORMAL._value_
    )

Answer 2

如果您想在自定义突变中使用 Enums，您可以像这样使用graphine.Enum。

class PermisionEnum(graphene.Enum):
    READ = "read"
    WRITE = "write"


class SimpleModelMutation(graphene.Mutation):

    class Arguments:
        # reusable
        permission = PermisionEnum(required=True)
        # not reusable
        scope = graphene.Enum('scope', [
            ("PERSONAL", "personal"),
            ("PROJECT", "project")
        ])(required=True)

我建议使用PermisionEnum(required=True) 方法，因为使用它PermisionEnum 类可以在不同的突变中重复使用。当您声明枚举时，这是不可能的，因为我使用 scope 归档！

Answer 3

您可以使用graphene.Enum.from_enum()。

该函数可以将普通的Enum类型转换为graphene.Enum。

请注意models.TextChoices 仅适用于 3.0 以上的 Dajango 版本

models.py（对于 Django 版本 >= 3.0）

from django.db import models

class SomeModel(models.Model):

    class SomeEnum(models.TextChoices):

        A = "A", _("Option A")
        B = "B", _("Option B")

    enum_field = models.CharField(
        max_length=1,
        choices=SomeEnum.choices,
        default=SomeEnum.A,
    )

models.py（适用于 Django 版本

from enum import Enum
class SomeEnum(Enum):
    A = "A"
    B = "B"

schema.py：

SomeEnumSchema = graphene.Enum.from_enum(SomeEnum)
class SomeMutation(graphene.Mutation):
    class Arguments:
        some_enum = SomeEnumSchema(required=True)