找不到页面（404）Django -generic.DetailView

Question

开发一个具有课程，课程和情节模型的项目。在剧集模型中有视频。但是问题是当我使用generic.TemplateView呈现模板时，模板可以工作，但是当我使用generic.DetailView时，错误提示“找不到页面（404）”。

无法理解该错误。

urls.py

package main

import (
    "log"
    "net/http"

    "github.com/gin-gonic/gin"
    "github.com/gin-gonic/gin/binding"
)

type ParamsOne struct {
    Username string `json:"username"`
}

type ParamsTwo struct {
    Username string `json:"username"`
}

func first(c *gin.Context) {
    c.Set("variable", "foo")
    c.Next()
}

func second(c *gin.Context) {
    v := c.MustGet("variable")
    log.Printf("in middleware %s", v)
    c.Next()
}

func main() {
    r := gin.New()
    r.Use(first)
    r.Use(second)
    r.POST("/", func(c *gin.Context) {
        var f ParamsOne
        if err := c.ShouldBindBodyWith(&f, binding.JSON); err != nil {
            log.Printf("%+v", err)
        }
        log.Printf("%+v", f)
        var ff ParamsTwo
        if err := c.ShouldBindBodyWith(&ff, binding.JSON); err != nil {
            log.Printf("%+v", err)
        }
        log.Printf("%+v", ff)
        v := c.MustGet("variable")
        log.Printf("in route %s", v)
        c.IndentedJSON(http.StatusOK, f)
    })
    r.Run(":4000")
}

views.py，当 TemplateView

example$ ./example
[GIN-debug] [WARNING] Running in "debug" mode. Switch to "release" mode in production.
 - using env:   export GIN_MODE=release
 - using code:  gin.SetMode(gin.ReleaseMode)

[GIN-debug] POST   /                         --> main.main.func1 (3 handlers)
[GIN-debug] Listening and serving HTTP on :4000
2020/07/05 13:11:06 in middleware foo
2020/07/05 13:11:06 {Username:somename}
2020/07/05 13:11:06 {Username:somename}
2020/07/05 13:11:06 in route foo

做得好。

DetailView

时为

views.py

from django.urls import path

from .views import (
    CourseDetailsView,
    LessonEpisodeVideoView,
)


urlpatterns = [
    path('course_detail/<slug:slug>/', CourseDetailsView.as_view(), name='course-detail'),
    path('course/detail/video/<slug:slug>/', LessonEpisodeVideoView.as_view(), name='episode-video'),
]

但是将 TemplaeView 更改为 DetailView 时，出现了错误！

在HTML超链接标记中：

class LessonEpisodeVideoView(TemplateView, LoginRequiredMixin):
    model = Courses
    template_name = 'courses/course_details.html'