如何在 Graphene Django 中过滤相关模型计数

问题描述

我有 2 个模型：

import uuid
from django.db import models


class Country(models.Model):
    name = models.CharField(max_length=255,unique=True)

    def city_count(self):
        return self.city_set.count()

class City(models.Model):
    country = models.ForeignKey('country.Country',on_delete=models.CASCADE)
    name = models.CharField(max_length=255)

和 2 个架构：

import graphene
from graphene_django.filter import DjangoFilterConnectionField

from core.utils import ExtendedDjangoObjectType

from .models import Country as CountryModel,City as CityModel


class Country(ExtendedDjangoObjectType):
    class Meta:
        model = CountryModel
        filter_fields = {
            'name': ['exact'],# 'city_count': ['exact'] => this does not work!
        }
        interfaces = (graphene.relay.Node,)

    city_count = graphene.Int()

    def resolve_city_count(self,info):
        return self.city_count()


class City(ExtendedDjangoObjectType):
    class Meta:
        model = CityModel
        filter_fields = ['name']
        interfaces = (graphene.relay.Node,)


class Query(graphene.ObjectType):
    country = graphene.relay.Node.Field(Country)
    countries = DjangoFilterConnectionField(Country)
    city = graphene.relay.Node.Field(City)
    cities = DjangoFilterConnectionField(City)

我可以查询 city_count 上的 countries，但我似乎无法对其进行过滤（精确，或 gte 大于 / lte 小于）

即这有效：

{
  countries(first: 10) {
    edges {
      node {
        name
        cityCount
      }
    }
  }
}

但这不会：

{
  countries(cityCount: 5) {
    edges {
      node {
        name
        cityCount
      }
    }
  }
}

并触发以下错误：

TypeError at /api/graphql/
'Meta.fields' must not contain non-model field names: city_count

知道如何对非模型字段进行过滤/排序吗？

解决方法

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