DRF: drf嵌套路由器:无法使用视图名称解析超链接关系的URL

Question

我在使用视图集显示模型的-detail时遇到问题。我对我的urls使用了drf-nested-routers包。

以下是与本课程相关的Course和Section的示例。(代码如下)

[
    {
        "url": "http://127.0.0.1:8000/courses/CS250/",
        "course_code": "CS250",
        "sections_offered": [
            "http://127.0.0.1:8000/courses/CS250/sections/01/"
        ]
    },
    {
        "url": "http://127.0.0.1:8000/courses/CS150/",
        "course_code": "CS150",
        "sections_offered": []
    }
]

只有在什么都没有的情况下，我才能导航到courses/CS250/sections，但是一旦我在那里创建了一个对象，我就不能再访问那个端点，我也不能访问该对象的URL (http://127.0.0.1:8000/courses/CS250/sections/01/)，除非得到这个错误：django.core.exceptions.ImproperlyConfigured: Could not resolve URL for hyperlinked relationship using view name "section-detail". You may have failed to include the related model in your API, or incorrectly configured the 'lookup_field' attribute on this field.

但是，我可以很好地导航到课程的url (http://127.0.0.1:8000/courses/CS250/)

/models.py

from django.db import models

class Course(models.Model):
    course_code = models.CharField(default='', max_length=50, primary_key=True)

class Section(models.Model):
    section_number = models.CharField(default='01', max_length=100, primary_key=True)
    parent_course = models.ForeignKey(Course, related_name="sections_offered", on_delete=models.CASCADE, blank=True, null=True)

/views.py

from . import models
from . import serializers
from rest_framework import viewsets

class CourseViewSet(viewsets.ModelViewSet):
    serializer_class = serializers.CourseSerializer
    queryset = models.Course.objects.all()

class SectionViewSet(viewsets.ModelViewSet):
    serializer_class = serializers.SectionSerializer
    queryset = models.Section.objects.all()

/serializers.py

from rest_framework_nested.relations import NestedHyperlinkedRelatedField
from rest_framework import serializers
from . import models

class CourseSerializer(serializers.HyperlinkedModelSerializer):

    sections_offered = NestedHyperlinkedRelatedField(
        many=True,
        read_only=True,
        view_name='section-detail',
        parent_lookup_kwargs={'parent_course_pk': 'parent_course__pk'}
    )

    class Meta:
        model = models.Course
        fields = ("url", "course_code", "sections_offered",)

class SectionSerializer(serializers.HyperlinkedModelSerializer):
    class Meta:
        model = models.Section
        fields = "__all__"

/urls.py

from rest_framework import routers
from . import views
from rest_framework_nested.routers import NestedSimpleRouter
from django.conf.urls import url, include

router = routers.DefaultRouter()
router.register(r'courses', views.CourseViewSet)
courses_router = NestedSimpleRouter(router, r'courses', lookup='parent_course')
courses_router.register(r'sections', views.SectionViewSet)
urlpatterns = [
    url(r'^', include(router.urls)),
    url(r'^', include(courses_router.urls)),
]

我认为SectionViewSet可能有问题，我可能需要覆盖视图集的retrieve()和list()函数，但我对如何处理这个bug感到相当困惑。这也可能是我的urls的问题。我是一个初学者，过了很长时间我都不知道我做错了什么。谢谢你的帮助。

Answer 1

修复无法查看部分详细信息的问题。我修改了代码，并将url字段修改为SectionSerializer，如下所示：

class SectionSerializer(serializers.HyperlinkedModelSerializer):
    url = serializers.HyperlinkedRelatedField(
        read_only=True,
        view_name='section-detail'
    )
    class Meta:
        model = models.Section
        fields = ('url', 'section_number', 'parent_course')

并且现在能够导航所有端点。我不知道为什么，所以我真的很感谢你对这种行为的解释。