Django学习之middleware的使用

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本文和大家分享的主要是django中middleware相关内容，一起来看看吧，希望对大家学习django有所帮助。

 

一、Django中间件的请求周期

 

我们从浏览器发出一个请求 Request，得到一个响应后的内容 HttpResponse ，这个请求传递到 Django的过程如下：

也就是说，每一个请求都是先通过中间件中的 process_request 函数，这个函数返回 None 或者 HttpResponse 对象，如果返回前者，继续处理其它中间件，如果返回一个 HttpResponse，就处理中止，返回到网页上。

 

二、自定义及注册中间件

 

1. 创建中间件

 

在project根目录下创建中间件py文件：

 

 

 1 class RequestExeute(object):

 2     def process_request(self, request):

 3         print(’process_request’)

 4

 5     def process_view(self, request, callback, callback_args, callback_kwargs):

 6         print(’process_view’)

 7

 8     def process_exception(self, request, exception):

 9         """

10         当views函数出错时执行

11         :param request:

12         :param exception:

13         :return:

14         """

15         print(’process_exception’)

16         

17     def process_response(self, request, response):

18         """

19         必须return HttpResponse

20         :param request:

21         :param response:

22         :return:

23         """

24         print(’process_response’)

25         return response

26

27     def process_template_response(self, request, response):

28         """

29         视图函数的返回值中，如果有render方法，才被调用

30         :param request:

31         :param response:

32         :return:

33         """

34         print(’process_template_response’)

35         return response

 

md.py

2. 注册中间件

 

在settings.py文件中，按照欲执行的顺序注册：

ps. 在1.9及之前的版本中，中间件的关键字为：MIDDLEWARE_CLASSES

 

MIDDLEWARE_CLASSES = (

    ’zqxt.middleware.BlockedIpMiddleware’,

    ...其它的中间件

)

三、中间件中方法的执行顺序

 

1. 正常状况

 

 1 from django.shortcuts import HttpResponse

 2 from django.utils.deprecation import MiddlewareMixin

 3 class M1(MiddlewareMixin):

 4     def process_request(self, request):

 5         print(’m1.request’)

 6         # return HttpResponse(’request_m1’)

 7

 8     def process_view(self, request, callback, callback_args, callback_kwargs):

 9         print(’m1.view’)

10         # response = callback(request, *callback_args, **callback_kwargs)

11         # return response

12

13     def process_response(self, request, response):

14         print(’m1.response’)

15         return response

16

17     def process_exception(self, request, exception):

18         print(’m1.process_exception’)

19         return HttpResponse(’m1.process_exception’)

20

21     def process_template_response(self, request, response):

22         """

23         视图函数的返回值中，如果有render方法，才被调用

24         :param request:

25         :param response:

26         :return:

27         """

28         print(’m1.process_template_response’)

29         return response

30

31

32 class M2(MiddlewareMixin):

33     def process_request(self, request):

34         print(’m2.request’)

35

36     def process_view(self, request, callback, callback_args, callback_kwargs):

37         print(’m2.view’)

38         # response = callback(request, *callback_args, **callback_kwargs)

39         # return response

40

41     def process_response(self, request, response):

42         print(’m2.response’)

43         return response

44

45     def process_exception(self, request, exception):

46         print(’m2.process_exception’)

47         return HttpResponse(’m2.process_exception’)

48

49     def process_template_response(self, request, response):

50         """

51         视图函数的返回值中，如果有render方法，才被调用

52         :param request:

53         :param response:

54         :return:

55         """

56         print(’m2.process_template_response’)

57         return response

 

process_request和process_view返回None

执行顺序：

 

m1.request

m2.request

m1.view

m2.view

m2.response

m1.response

2. 在版本1.10及之后

 

若process_request返回HttpResponse 对象，则从当前中间件的process_response向前返回

 

 

 1 from django.shortcuts import HttpResponse

 2 from django.utils.deprecation import MiddlewareMixin

 3 class M1(MiddlewareMixin):

 4     def process_request(self, request):

 5         print(’m1.request’)

 6         return HttpResponse(’request_m1’)

 7

 8     def process_view(self, request, callback, callback_args, callback_kwargs):

 9         print(’m1.view’)

10         # response = callback(request, *callback_args, **callback_kwargs)

11         # return response

12

13     def process_response(self, request, response):

14         print(’m1.response’)

15         return response

16

17     def process_exception(self, request, exception):

18         print(’m1.process_exception’)

19         return HttpResponse(’m1.process_exception’)

20

21     def process_template_response(self, request, response):

22         """

23         视图函数的返回值中，如果有render方法，才被调用

24         :param request:

25         :param response:

26         :return:

27         """

28         print(’m1.process_template_response’)

29         return response

30

31

32 class M2(MiddlewareMixin):

33     def process_request(self, request):

34         print(’m2.request’)

35

36     def process_view(self, request, callback, callback_args, callback_kwargs):

37         print(’m2.view’)

38         # response = callback(request, *callback_args, **callback_kwargs)

39         # return response

40

41     def process_response(self, request, response):

42         print(’m2.response’)

43         return response

44

45     def process_exception(self, request, exception):

46         print(’m2.process_exception’)

47         return HttpResponse(’m2.process_exception’)

48

49     def process_template_response(self, request, response):

50         """

51         视图函数的返回值中，如果有render方法，才被调用

52         :param request:

53         :param response:

54         :return:

55         """

56         print(’m2.process_template_response’)

57         return response

58

59

60 # class RequestExeute(object):

61 #     def process_request(self, request):

62 #         print(’process_request’)

63 #

64 #     def process_view(self, request, callback, callback_args, callback_kwargs):

65 #         print(’process_view’)

66 #

67 #     def process_exception(self, request, exception):

68 #         """

69 #         当views函数出错时执行

70 #         :param request:

71 #         :param exception:

72 #         :return:

73 #         """

74 #         print(’process_exception’)

75 #

76 #     def process_response(self, request, response):

77 #         """

78 #         必须return HttpResponse

79 #         :param request:

80 #         :param response:

81 #         :return:

82 #         """

83 #         print(’process_response’)

84 #         return response

85 #

86 #     def process_template_response(self, request, response):

87 #         """

88 #         视图函数的返回值中，如果有render方法，才被调用

89 #         :param request:

90 #         :param response:

91 #         :return:

92 #         """

93 #         print(’process_template_response’)

94 #         return response

 

M1的process_request返回HttpResponse

执行顺序：

 

m1.request

m1.response

process_view与process_request类似：

 

 

 1 from django.shortcuts import HttpResponse

 2 from django.utils.deprecation import MiddlewareMixin

 3 class M1(MiddlewareMixin):

 4     def process_request(self, request):

 5         print(’m1.request’)

 6         # return HttpResponse(’request_m1’)

 7

 8     def process_view(self, request, callback, callback_args, callback_kwargs):

 9         print(’m1.view’)

10         response = callback(request, *callback_args, **callback_kwargs)

11         return response

12

13     def process_response(self, request, response):

14         print(’m1.response’)

15         return response

16

17     def process_exception(self, request, exception):

18         print(’m1.process_exception’)

19         return HttpResponse(’m1.process_exception’)

20

21     def process_template_response(self, request, response):

22         """

23         视图函数的返回值中，如果有render方法，才被调用

24         :param request:

25         :param response:

26         :return:

27         """

28         print(’m1.process_template_response’)

29         return response

30

31

32 class M2(MiddlewareMixin):

33     def process_request(self, request):

34         print(’m2.request’)

35

36     def process_view(self, request, callback, callback_args, callback_kwargs):

37         print(’m2.view’)

38         # response = callback(request, *callback_args, **callback_kwargs)

39         # return response

40

41     def process_response(self, request, response):

42         print(’m2.response’)

43         return response

44

45     def process_exception(self, request, exception):

46         print(’m2.process_exception’)

47         return HttpResponse(’m2.process_exception’)

48

49     def process_template_response(self, request, response):

50         """

51         视图函数的返回值中，如果有render方法，才被调用

52         :param request:

53         :param response:

54         :return:

55         """

56         print(’m2.process_template_response’)

57         return response

 

m1的process_view返回HttpResponse

执行顺序：

 

m1.request

m2.request

m1.view

m2.response

m1.response

 

3. 在版本1.10之前

 

若process_request返回HttpResponse 对象，则当前中间件之后的process_request都不会执行，而从最后一个中间件的process_response向前返回

 

 

来源：博客园

Django学习之middleware的使用

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