Django-视图CBV执行流程详解

淡淡的烟草味﹌ 2022-02-13 02:47 228阅读 0赞

*  FBV和CBV其实就是要么写函数要么写类,那么内部原理是怎么实现?

## FBV写法 ##

def func_view(request):
        "Function views"
        if request.method == "GET":
            return HttpResponse("GET-请求")
        elif request.method == "POST":
            return HttpResponse('POST-请求')
        elif request.method == "PUT":
            return HttpResponse('PUT-请求')
        elif request.method == "DELETE":
            return HttpResponse('DELETE-请求')
        else:
            return HttpResponse("不支持的请求类型")

## CBV写法 ##

class MyClassView(View):
        def get(self, request, *args, **kwargs):
            return HttpResponse("GET-请求")
    
        def post(self, request, *args, **kwargs):
            return HttpResponse("POST-请求")
    
        def put(self, request, *args, **kwargs):
            return HttpResponse("PUT-请求")
    
        def delete(self, request, *args, **kwargs):
            return HttpResponse("DELETE-请求")

## 原理 ##

*  FBV可以直接通过路由，调用到相应的视图函数,那么CBV呢?

![img\_ed1803c6efe0573b9527bf70d116f013.png][img_ed1803c6efe0573b9527bf70d116f013.png]

微信截图\_20190107211036

*  在我们的MyClassViewl里面没有as\_view(),所以我们可以去父类找

![img\_2a8b6426b11c002333b88793cacc2f96.png][img_2a8b6426b11c002333b88793cacc2f96.png]

微信截图\_20190107211509

*  父类的as\_view()方法

![img\_f2e25ad484e30c57017cbe866975eac0.png][img_f2e25ad484e30c57017cbe866975eac0.png]

微信截图\_20190107211710

*  在as\_view()中也返回一个view

![img\_4c854659141dc05a2636d857601cfc90.png][img_4c854659141dc05a2636d857601cfc90.png]

微信截图\_20190107212833

*  分析as\_view()当中的代码,调用了dispatch()方法

![img\_6e85d87c7a8c874badea6be2239996d9.png][img_6e85d87c7a8c874badea6be2239996d9.png]

微信截图\_20190107213123

*  在分析dispatch()方法前,我们先看看,当请求进来,通过URL先执行了as\_view()函数,本质还是在执行内部的view()函数,而view()函数内部是执行了dispatch()方法

![img\_46e28bb764eb8dbb37471729debb085c.png][img_46e28bb764eb8dbb37471729debb085c.png]

微信截图\_20190107213809

*  不管什么请求进来,都执行dispatch()

![img\_afda5ba44e0eac94befc41ce4de866af.png][img_afda5ba44e0eac94befc41ce4de866af.png]

微信截图\_20190107213912

*  由于我们MyClassView里面没有dispatch()方法,所以会调用父类的dispatch(),如果我们有,那么会调用我们自己写的dispatch()方法

![img\_e3f975a12710557809370221b395600d.png][img_e3f975a12710557809370221b395600d.png]

微信截图\_20190107214135

*  postman验证([http://127.0.0.1:8000/myclass\_view/][http_127.0.0.1_8000_myclass_view]) 我们发现调用了我们自己写的dispatch()方法

![img\_fc1bb02a4a071ba4a335a268a79f64a5.png][img_fc1bb02a4a071ba4a335a268a79f64a5.png]

微信截图\_20190107214459

*  我们可以不看父类如何实现,我们可以自己尝试的写一下

![img\_5b2828dc008d631f9a4efdd3831bed1c.png][img_5b2828dc008d631f9a4efdd3831bed1c.png]

微信截图\_20190107214847

*  通过postman验证,发现也完成了这个相同的功能

![img\_dd7215c975dfb60ece0921ce0bb2a41f.png][img_dd7215c975dfb60ece0921ce0bb2a41f.png]

微信截图\_20190107215246

*  修正错误

![img\_5ba7ef97019af7b6b11724214ed5513b.png][img_5ba7ef97019af7b6b11724214ed5513b.png]

微信截图\_20190107215130

*  postman验证效果

![img\_6e55beb32f4cf7cf25ffd03ab84835c7.png][img_6e55beb32f4cf7cf25ffd03ab84835c7.png]

微信截图\_20190107215339

*  观察父类的dispatch做什么?(其实本质就是基于反射实现)

![img\_a10eb3c1d24b00daf21c1ca77706b446.png][img_a10eb3c1d24b00daf21c1ca77706b446.png]

微信截图\_20190107215905

结论: CBV基于反射实现根据请求方式不同,执行不同方法

原理总结:  
路由url -- > view函数 --> dispatch方法(根据反射来执行:GET/POST/PUT/DELETE等等....)

[img_ed1803c6efe0573b9527bf70d116f013.png]: /images/20220213/b495bddff9b14c00ac16773e2901dacf.png
[img_2a8b6426b11c002333b88793cacc2f96.png]: /images/20220213/4a77d34c13474662abd0c56e4f90d442.png
[img_f2e25ad484e30c57017cbe866975eac0.png]: /images/20220213/9cffa0a2e5bb404dba0d7a66a256ab8b.png
[img_4c854659141dc05a2636d857601cfc90.png]: /images/20220213/d0453c9cd01143d781ec3877d2810d52.png
[img_6e85d87c7a8c874badea6be2239996d9.png]: /images/20220213/2dda7da0861a4c619852218222bcb74c.png
[img_46e28bb764eb8dbb37471729debb085c.png]: /images/20220213/9567f7ec88fe4ee2a53d9d3dbd1b88ac.png
[img_afda5ba44e0eac94befc41ce4de866af.png]: /images/20220213/aea985d789954a3c9dc2d5b4d0aa401f.png
[img_e3f975a12710557809370221b395600d.png]: /images/20220213/9b4bc2e9a4c84cfcbb167c7dbc8e29fb.png
[http_127.0.0.1_8000_myclass_view]: http://127.0.0.1:8000/myclass_view/
[img_fc1bb02a4a071ba4a335a268a79f64a5.png]: /images/20220213/06afeceb2cdb4299b5e941a183275e34.png
[img_5b2828dc008d631f9a4efdd3831bed1c.png]: /images/20220213/2c44a98453384f44a45c89d9a8f44845.png
[img_dd7215c975dfb60ece0921ce0bb2a41f.png]: /images/20220213/62b6a9b3e45e437bb84b24b68b31e10b.png
[img_5ba7ef97019af7b6b11724214ed5513b.png]: /images/20220213/f83137fefe9c48b6a272376a48d1c3f9.png
[img_6e55beb32f4cf7cf25ffd03ab84835c7.png]: /images/20220213/6b098c4c15b542ac8c1e594e41bab22a.png
[img_a10eb3c1d24b00daf21c1ca77706b446.png]: /images/20220213/e2ad364fb73d489e851f371434695737.png