Django 与 Graphite 烯 : How to handle bidirectional relationship with polmorphic models?

Question

我有一个看起来像这样的 Django 模型(当然是简化的):

from django.db import models
from polymorphic.models import PolymorphicModel

class Tournament(models.Model):
    slug = models.CharField(max_length=100, unique=True)

class Event(PolymorphicModel):
    tournament = models.ForeignKey(Tournament, related_name='events')
    slug = models.CharField(max_length=100)

class PracticeEvent(Event):
    pass

class MatchEvent(Event):
    winner = models.CharField(max_length=100, null=True, blank=True, default=None)

锦标赛包括两种类型的赛事:练习赛和比赛。我想使用 GraphQL、使用 Graphene 来公开这个模型。这是我想到的:

import graphene
from graphene_django import DjangoObjectType

from . import models

class TournamentType(DjangoObjectType):
    class Meta:
        model = models.Tournament
        exclude_fields = ('id',)

class EventType(graphene.Interface):
    tournament = graphene.Field(TournamentType, required=True)
    slug = graphene.String(required=True)

class PracticeEventType(DjangoObjectType):
    class Meta:
        model = models.PracticeEvent
        interfaces = (EventType,)
        exclude_fields = ('id',)

class MatchEventType(DjangoObjectType):
    class Meta:
        model = models.MatchEvent
        interfaces = (EventType,)
        exclude_fields = ('id',)

extra_types = {PracticeEventType, MatchEventType}

class Query(graphene.ObjectType):
    tournaments = graphene.List(TournamentType)
    events = graphene.List(EventType)
    # ... resolvers ...

schema = graphene.Schema(
    query=Query,
    types=schema_joust.extra_types,)

到目前为止，一切顺利；我可以直接查询events { ... }，甚至锦标赛也可用。但是，由于 model = models.Event 中没有 DjangoObjectType，因此我无法查询 tournaments { events {...} }。 ..

我该如何解决这个问题？我无法将 EventType 设为 DjangoObjectTpe，并且我不知道在事后添加 events 字段。

Answer 1

靠自己，EventType.tournament和TournamentType.events没那么难。第一个如问题所示，第二个可以这样实现:

class EventType(graphene.Interface):
    slug = graphene.String(required=True)

class TournamentType(DjangoObjectType):
    class Meta:
        model = models.Tournament
        exclude_fields = ('id',)

    events = graphene.List(EventType)

    def resolve_events(self, info):
        return self.events.all()

graphene-django 无法识别这种关系，但手动声明和解析该字段可以解决问题。还可以获得反向字段，如果我们不需要引用TournamentType，这将起作用。 ，我深入研究 graphene-django 并发现 graphene_django.converter.convert_django_field_with_choices 。这让我们可以像这样定义字段:

import graphene
from graphene_django import DjangoObjectType, converter, registry

from . import models

class EventType(graphene.Interface):
    tournament = converter.convert_django_field_with_choices(
        models.Event.tournament.field, registry.get_global_registry())
    slug = graphene.String(required=True)