如何将字段列表动态添加到 GraphQL ObjectType

Question

我有以下代码：

from starlette_graphene3 import GraphQLApp
import graphene

app = = APIRouter(
    dependencies=[Depends(auth_middleware)],
)

DYNAMIC_TYPES = {
    "length": graphene.Int(),
    "authors": graphene.List(of_type=str),
    "deprecated": graphene.String()
}

class MetaDataObject(graphene.ObjectType):
    resource_type = graphene.String()
    resource_name = graphene.String()

# I need to be able to do this somehow - specify a list of fieds and types dynamically.
for attr, g_type in DYNAMIC_TYPES.items():
    setattr(MetaDataObject, attr, g_type)


class Query(graphene.ObjectType):
    get_metadata = graphene.Field(MetaDataObject, resource_type=graphene.String(), resource_name=graphene.String())

    def resolve_get_metadata(self, info, resource_type, resource_name):

        response = table.get_item(
            Key={
                'resource_type': resource_type,
                'resource_name': resource_name
            }
        )

        if 'Item' not in response:
            return None

        return response['Item']


schema = graphene.Schema(query=Query, auto_camelcase=False)
app.add_route("/graphql", GraphQLApp(schema=schema))

如上所述，我需要能够动态指定字段和类型列表并将其附加到元数据 Object。问题是graphe.ObjectType不是常规的 Python class，它有一个特殊的元类来处理一些幕后工作，但我不确定如何使用元类。

Answer 1

您可以在 MetaDataObject class 中创建一个 graphene.Dynamic 字段，它可以接受字段和类型列表作为参数。

您可以使用graphene.Field来定义字段，使用graphene.List或graphene.NonNull来定义字段的类型。

喜欢;

class MetaDataObject(graphene.ObjectType):
    resource_type = graphene.String()
    resource_name = graphene.String()
    dynamic_fields = graphene.List(graphene.Field(graphene.String))

然后，您可以在创建元数据对象 class 的实例时将字段和类型列表传递给它。

喜欢;

metadata_object = MetaDataObject(dynamic_fields=[graphene.Field(graphene.String, name='field_name')])