GraphQL：如何对节点的“外键”设置项进行排序？答案

【问题标题】：GraphQL: how to sort node's "foreign key" set items?GraphQL：如何对节点的“外键”设置项进行排序？
【发布时间】：2018-09-26 10:17:43
【问题描述】：

我使用 Django，graphene-django 和 django-filter 构建 GraphQL api 并遇到 orderBy 的问题：

总的来说：我有院系，每个院系都有几个系。我可以对院系进行排序，但不能对部门进行相同的排序。

Django 模型：

class Faculty(models.Model):
    code = models.CharField(...)

class Department(models.Model):
    code = models.CharField(...)
    faculty = models.ForeignKey(
        Faculty,
        on_delete=models.CASCADE,
        related_name="departments",
    )

为了能够对我添加的院系进行排序：

import graphene
import django_filters
from graphene import relay, ObjectType
from django_filters import OrderingFilter
from graphene_django.types import DjangoObjectType
from graphene_django.filter import DjangoFilterConnectionField

class FacultyFilter(django_filters.FilterSet):
    class Meta:
        model = Faculty
        fields = ['university']
    order_by = OrderingFilter(fields=('code',))

class DepartmentFilter(django_filters.FilterSet):
    class Meta:
        model = Department
        fields = ['university', 'faculty']
    order_by = OrderingFilter(fields=('code',))

class Query(object):
    faculty = relay.Node.Field(FacultyNode)
    all_faculties = DjangoFilterConnectionField(
        FacultyNode,
        filterset_class=FacultyFilter,
    )

    department = relay.Node.Field(DepartmentNode)
    all_departments = DjangoFilterConnectionField(
        DepartmentNode,
        filterset_class=DepartmentFilter,
    )

为什么我不能对一组部门进行排序？

【问题讨论】：

标签： python django graphql graphene-python

【解决方案1】：

将此字段添加到节点：

class FacultyNode(DjangoObjectType):
    departments = DjangoFilterConnectionField(
        DepartmentNode,  # lambda: DepartmentNode (if Node is defined later)
        filterset_class=DepartmentFilter,
    )

【讨论】：