Django 的 CBV&FBV

Django FBV, function base view  视图里使用函数处理请求

url

url(r‘^users/‘, views.users),

views

from django.shortcuts import HttpResponse
import json
def users(request):
    user_list = ['lcg','superman']
    return HttpResponse(json.dumps((user_list)))

Django CBV, class base view 视图里使用类处理请求

url

url(r'^students/', views.StudentsView.as_view()),

views

from django.shortcuts import HttpResponse
from django.views import View

class StudentsView(View):

    def get(self,request,*args,**kwargs):
        return HttpResponse('GET')

    def post(self, request, *args, **kwargs):
        return HttpResponse('POST')

    def put(self, request, *args, **kwargs):
        return HttpResponse('PUT')

    def delete(self, request, *args, **kwargs):
        return HttpResponse('DELETE')

注意:

  • cbv定义类的时候必须要继承view
  • 在写url的时候必须要加as_view
  • 类里面使用form表单提交的话只有get和post方法
  • 类里面使用ajax发送数据的话支持定义以下很多方法
    restful规范:
    'get'获取数据, 'post'创建新数据, 'put'更新, 'patch'局部更新, 'delete'删除, 'head', 'options', 'trace'

CBV原理:继承,反射。

点进StudentView继承的View可以看到如下代码

class View(object):
    """
    Intentionally simple parent class for all views. Only implements
    dispatch-by-method and simple sanity checking.
    """

    http_method_names = ['get', 'post', 'put', 'patch', 'delete', 'head', 'options', 'trace']

    def __init__(self, **kwargs):
        """
        Constructor. Called in the URLconf; can contain helpful extra
        keyword arguments, and other things.
        """
        # Go through keyword arguments, and either save their values to our
        # instance, or raise an error.
        for key, value in six.iteritems(kwargs):
            setattr(self, key, value)

    @classonlymethod
    def as_view(cls, **initkwargs):
        """
        Main entry point for a request-response process.
        """
        for key in initkwargs:
            if key in cls.http_method_names:
                raise TypeError("You tried to pass in the %s method name as a "
                                "keyword argument to %s(). Don't do that."
                                % (key, cls.__name__))
            if not hasattr(cls, key):
                raise TypeError("%s() received an invalid keyword %r. as_view "
                                "only accepts arguments that are already "
                                "attributes of the class." % (cls.__name__, key))

        def view(request, *args, **kwargs):
            self = cls(**initkwargs)
            if hasattr(self, 'get') and not hasattr(self, 'head'):
                self.head = self.get
            self.request = request
            self.args = args
            self.kwargs = kwargs
            return self.dispatch(request, *args, **kwargs)
        view.view_class = cls
        view.view_initkwargs = initkwargs

        # take name and docstring from class
        update_wrapper(view, cls, updated=())

        # and possible attributes set by decorators
        # like csrf_exempt from dispatch
        update_wrapper(view, cls.dispatch, assigned=())
        return view

    def dispatch(self, request, *args, **kwargs):
        # Try to dispatch to the right method; if a method doesn't exist,
        # defer to the error handler. Also defer to the error handler if the
        # request method isn't on the approved list.
        if request.method.lower() in self.http_method_names:
            handler = getattr(self, request.method.lower(), self.http_method_not_allowed)
        else:
            handler = self.http_method_not_allowed
        return handler(request, *args, **kwargs)

    def http_method_not_allowed(self, request, *args, **kwargs):
        logger.warning(
            'Method Not Allowed (%s): %s', request.method, request.path,
            extra={'status_code': 405, 'request': request}
        )
        return http.HttpResponseNotAllowed(self._allowed_methods())

    def options(self, request, *args, **kwargs):
        """
        Handles responding to requests for the OPTIONS HTTP verb.
        """
        response = http.HttpResponse()
        response['Allow'] = ', '.join(self._allowed_methods())
        response['Content-Length'] = '0'
        return response

    def _allowed_methods(self):
        return [m.upper() for m in self.http_method_names if hasattr(self, m)]

View类里面的部分如下:

@classonlymethod
def as_view(cls, **initkwargs):
    """
    Main entry point for a request-response process.
    """
    for key in initkwargs:
        if key in cls.http_method_names:
            raise TypeError("You tried to pass in the %s method name as a "
                            "keyword argument to %s(). Don't do that."
                            % (key, cls.__name__))
        if not hasattr(cls, key):
            raise TypeError("%s() received an invalid keyword %r. as_view "
                            "only accepts arguments that are already "
                            "attributes of the class." % (cls.__name__, key))

    def view(request, *args, **kwargs):
        self = cls(**initkwargs)
        if hasattr(self, 'get') and not hasattr(self, 'head'):
            self.head = self.get
        self.request = request
        self.args = args
        self.kwargs = kwargs
        return self.dispatch(request, *args, **kwargs)
    view.view_class = cls
    view.view_initkwargs = initkwargs

    # take name and docstring from class
    update_wrapper(view, cls, updated=())

    # and possible attributes set by decorators
    # like csrf_exempt from dispatch
    update_wrapper(view, cls.dispatch, assigned=())
    return view

上面实质上是路由里面的那里写的as_view ,返回值是view 而view方法返回的是self.dispath。

http_method_names = ['get', 'post', 'put', 'patch', 'delete', 'head', 'options', 'trace']

该列表定义了八种客户端对服务端的访问方式

从路由到视图这个过程,会自动初始化该StudentView对象,并执行在类里写好的诸多方法,其中较为关键的是dispatch方法(通过as_view)。

def dispatch(self, request, *args, **kwargs):
    # Try to dispatch to the right method; if a method doesn't exist,
    # defer to the error handler. Also defer to the error handler if the
    # request method isn't on the approved list.
    if request.method.lower() in self.http_method_names:
        handler = getattr(self, request.method.lower(), self.http_method_not_allowed)
    else:
        handler = self.http_method_not_allowed
    return handler(request, *args, **kwargs)

函数主要是对客户端发来的请求进行分类处理,按照对应的方法去处理,也就是我们在FBV函数里经常写到的request.method。

也就是说,继承自View的类下的所有的方法本质上都是通过dispatch这个函数反射执行,如果想要在执行get或post方法前执行其他步骤,可以重写dispatch。

Django REST framework CBV

url

url(r'^students/', views.StudentsView.as_view()),

views

from rest_framework.views import APIView
from django.shortcuts import HttpResponse

class StudentsView(APIView):

    def get(self, request, *args, **kwargs):
        return HttpResponse('GET')

    def post(self, request, *args, **kwargs):
        return HttpResponse('POST')

    def put(self, request, *args, **kwargs):
        return HttpResponse('PUT')

    def delete(self, request, *args, **kwargs):
        return HttpResponse('DELETE')

rest_framework.views里面导入的APIView实际上是对Django的View的一个封装

Django REST framework CBV的原理与Django的原理是一样的。路由里面的那里写的as_view ,返回值是view 而view方法返回的是self.dispath。APIView基础了View,并且重写了dispath方法。APIView中的dispatch方法有很多的功能

class APIView(View):

    # The following policies may be set at either globally, or per-view.
    renderer_classes = api_settings.DEFAULT_RENDERER_CLASSES
    parser_classes = api_settings.DEFAULT_PARSER_CLASSES
    authentication_classes = api_settings.DEFAULT_AUTHENTICATION_CLASSES
    throttle_classes = api_settings.DEFAULT_THROTTLE_CLASSES
    permission_classes = api_settings.DEFAULT_PERMISSION_CLASSES
    content_negotiation_class = api_settings.DEFAULT_CONTENT_NEGOTIATION_CLASS
    metadata_class = api_settings.DEFAULT_METADATA_CLASS
    versioning_class = api_settings.DEFAULT_VERSIONING_CLASS

    # Allow dependency injection of other settings to make testing easier.
    settings = api_settings

    schema = DefaultSchema()

    @classmethod
    def as_view(cls, **initkwargs):
        """
        Store the original class on the view function.

        This allows us to discover information about the view when we do URL
        reverse lookups.  Used for breadcrumb generation.
        """
        if isinstance(getattr(cls, 'queryset', None), models.query.QuerySet):
            def force_evaluation():
                raise RuntimeError(
                    'Do not evaluate the `.queryset` attribute directly, '
                    'as the result will be cached and reused between requests. '
                    'Use `.all()` or call `.get_queryset()` instead.'
                )
            cls.queryset._fetch_all = force_evaluation

        view = super(APIView, cls).as_view(**initkwargs)
        view.cls = cls
        view.initkwargs = initkwargs

        # Note: session based authentication is explicitly CSRF validated,
        # all other authentication is CSRF exempt.
        return csrf_exempt(view)

    @property
    def allowed_methods(self):
        """
        Wrap Django's private `_allowed_methods` interface in a public property.
        """
        return self._allowed_methods()

    @property
    def default_response_headers(self):
        headers = {
            'Allow': ', '.join(self.allowed_methods),
        }
        if len(self.renderer_classes) > 1:
            headers['Vary'] = 'Accept'
        return headers

    def http_method_not_allowed(self, request, *args, **kwargs):
        """
        If `request.method` does not correspond to a handler method,
        determine what kind of exception to raise.
        """
        raise exceptions.MethodNotAllowed(request.method)

    def permission_denied(self, request, message=None):
        """
        If request is not permitted, determine what kind of exception to raise.
        """
        if request.authenticators and not request.successful_authenticator:
            raise exceptions.NotAuthenticated()
        raise exceptions.PermissionDenied(detail=message)

    def throttled(self, request, wait):
        """
        If request is throttled, determine what kind of exception to raise.
        """
        raise exceptions.Throttled(wait)

    def get_authenticate_header(self, request):
        """
        If a request is unauthenticated, determine the WWW-Authenticate
        header to use for 401 responses, if any.
        """
        authenticators = self.get_authenticators()
        if authenticators:
            return authenticators[0].authenticate_header(request)

    def get_parser_context(self, http_request):
        """
        Returns a dict that is passed through to Parser.parse(),
        as the `parser_context` keyword argument.
        """
        # Note: Additionally `request` and `encoding` will also be added
        #       to the context by the Request object.
        return {
            'view': self,
            'args': getattr(self, 'args', ()),
            'kwargs': getattr(self, 'kwargs', {})
        }

    def get_renderer_context(self):
        """
        Returns a dict that is passed through to Renderer.render(),
        as the `renderer_context` keyword argument.
        """
        # Note: Additionally 'response' will also be added to the context,
        #       by the Response object.
        return {
            'view': self,
            'args': getattr(self, 'args', ()),
            'kwargs': getattr(self, 'kwargs', {}),
            'request': getattr(self, 'request', None)
        }

    def get_exception_handler_context(self):
        """
        Returns a dict that is passed through to EXCEPTION_HANDLER,
        as the `context` argument.
        """
        return {
            'view': self,
            'args': getattr(self, 'args', ()),
            'kwargs': getattr(self, 'kwargs', {}),
            'request': getattr(self, 'request', None)
        }

    def get_view_name(self):
        """
        Return the view name, as used in OPTIONS responses and in the
        browsable API.
        """
        func = self.settings.VIEW_NAME_FUNCTION
        return func(self.__class__, getattr(self, 'suffix', None))

    def get_view_description(self, html=False):
        """
        Return some descriptive text for the view, as used in OPTIONS responses
        and in the browsable API.
        """
        func = self.settings.VIEW_DESCRIPTION_FUNCTION
        return func(self.__class__, html)

    # API policy instantiation methods

    def get_format_suffix(self, **kwargs):
        """
        Determine if the request includes a '.json' style format suffix
        """
        if self.settings.FORMAT_SUFFIX_KWARG:
            return kwargs.get(self.settings.FORMAT_SUFFIX_KWARG)

    def get_renderers(self):
        """
        Instantiates and returns the list of renderers that this view can use.
        """
        return [renderer() for renderer in self.renderer_classes]

    def get_parsers(self):
        """
        Instantiates and returns the list of parsers that this view can use.
        """
        return [parser() for parser in self.parser_classes]

    def get_authenticators(self):
        """
        Instantiates and returns the list of authenticators that this view can use.
        """
        return [auth() for auth in self.authentication_classes]

    def get_permissions(self):
        """
        Instantiates and returns the list of permissions that this view requires.
        """
        return [permission() for permission in self.permission_classes]

    def get_throttles(self):
        """
        Instantiates and returns the list of throttles that this view uses.
        """
        return [throttle() for throttle in self.throttle_classes]

    def get_content_negotiator(self):
        """
        Instantiate and return the content negotiation class to use.
        """
        if not getattr(self, '_negotiator', None):
            self._negotiator = self.content_negotiation_class()
        return self._negotiator

    def get_exception_handler(self):
        """
        Returns the exception handler that this view uses.
        """
        return self.settings.EXCEPTION_HANDLER

    # API policy implementation methods

    def perform_content_negotiation(self, request, force=False):
        """
        Determine which renderer and media type to use render the response.
        """
        renderers = self.get_renderers()
        conneg = self.get_content_negotiator()

        try:
            return conneg.select_renderer(request, renderers, self.format_kwarg)
        except Exception:
            if force:
                return (renderers[0], renderers[0].media_type)
            raise

    def perform_authentication(self, request):
        """
        Perform authentication on the incoming request.

        Note that if you override this and simply 'pass', then authentication
        will instead be performed lazily, the first time either
        `request.user` or `request.auth` is accessed.
        """
        request.user

    def check_permissions(self, request):
        """
        Check if the request should be permitted.
        Raises an appropriate exception if the request is not permitted.
        """
        for permission in self.get_permissions():
            if not permission.has_permission(request, self):
                self.permission_denied(
                    request, message=getattr(permission, 'message', None)
                )

    def check_object_permissions(self, request, obj):
        """
        Check if the request should be permitted for a given object.
        Raises an appropriate exception if the request is not permitted.
        """
        for permission in self.get_permissions():
            if not permission.has_object_permission(request, self, obj):
                self.permission_denied(
                    request, message=getattr(permission, 'message', None)
                )

    def check_throttles(self, request):
        """
        Check if request should be throttled.
        Raises an appropriate exception if the request is throttled.
        """
        for throttle in self.get_throttles():
            if not throttle.allow_request(request, self):
                self.throttled(request, throttle.wait())

    def determine_version(self, request, *args, **kwargs):
        """
        If versioning is being used, then determine any API version for the
        incoming request. Returns a two-tuple of (version, versioning_scheme)
        """
        if self.versioning_class is None:
            return (None, None)
        scheme = self.versioning_class()
        return (scheme.determine_version(request, *args, **kwargs), scheme)

    # Dispatch methods

    def initialize_request(self, request, *args, **kwargs):
        """
        Returns the initial request object.
        """
        parser_context = self.get_parser_context(request)

        return Request(
            request,
            parsers=self.get_parsers(),
            authenticators=self.get_authenticators(),
            negotiator=self.get_content_negotiator(),
            parser_context=parser_context
        )

    def initial(self, request, *args, **kwargs):
        """
        Runs anything that needs to occur prior to calling the method handler.
        """
        self.format_kwarg = self.get_format_suffix(**kwargs)

        # Perform content negotiation and store the accepted info on the request
        neg = self.perform_content_negotiation(request)
        request.accepted_renderer, request.accepted_media_type = neg

        # Determine the API version, if versioning is in use.
        version, scheme = self.determine_version(request, *args, **kwargs)
        request.version, request.versioning_scheme = version, scheme

        # Ensure that the incoming request is permitted
        self.perform_authentication(request)
        self.check_permissions(request)
        self.check_throttles(request)

    def finalize_response(self, request, response, *args, **kwargs):
        """
        Returns the final response object.
        """
        # Make the error obvious if a proper response is not returned
        assert isinstance(response, HttpResponseBase), (
            'Expected a `Response`, `HttpResponse` or `HttpStreamingResponse` '
            'to be returned from the view, but received a `%s`'
            % type(response)
        )

        if isinstance(response, Response):
            if not getattr(request, 'accepted_renderer', None):
                neg = self.perform_content_negotiation(request, force=True)
                request.accepted_renderer, request.accepted_media_type = neg

            response.accepted_renderer = request.accepted_renderer
            response.accepted_media_type = request.accepted_media_type
            response.renderer_context = self.get_renderer_context()

        # Add new vary headers to the response instead of overwriting.
        vary_headers = self.headers.pop('Vary', None)
        if vary_headers is not None:
            patch_vary_headers(response, cc_delim_re.split(vary_headers))

        for key, value in self.headers.items():
            response[key] = value

        return response

    def handle_exception(self, exc):
        """
        Handle any exception that occurs, by returning an appropriate response,
        or re-raising the error.
        """
        if isinstance(exc, (exceptions.NotAuthenticated,
                            exceptions.AuthenticationFailed)):
            # WWW-Authenticate header for 401 responses, else coerce to 403
            auth_header = self.get_authenticate_header(self.request)

            if auth_header:
                exc.auth_header = auth_header
            else:
                exc.status_code = status.HTTP_403_FORBIDDEN

        exception_handler = self.get_exception_handler()

        context = self.get_exception_handler_context()
        response = exception_handler(exc, context)

        if response is None:
            self.raise_uncaught_exception(exc)

        response.exception = True
        return response

    def raise_uncaught_exception(self, exc):
        if settings.DEBUG:
            request = self.request
            renderer_format = getattr(request.accepted_renderer, 'format')
            use_plaintext_traceback = renderer_format not in ('html', 'api', 'admin')
            request.force_plaintext_errors(use_plaintext_traceback)
        raise

    # Note: Views are made CSRF exempt from within `as_view` as to prevent
    # accidental removal of this exemption in cases where `dispatch` needs to
    # be overridden.
    def dispatch(self, request, *args, **kwargs):
        """
        `.dispatch()` is pretty much the same as Django's regular dispatch,
        but with extra hooks for startup, finalize, and exception handling.
        """
        self.args = args
        self.kwargs = kwargs
        request = self.initialize_request(request, *args, **kwargs)
        self.request = request
        self.headers = self.default_response_headers  # deprecate?

        try:
            self.initial(request, *args, **kwargs)

            # Get the appropriate handler method
            if request.method.lower() in self.http_method_names:
                handler = getattr(self, request.method.lower(),
                                  self.http_method_not_allowed)
            else:
                handler = self.http_method_not_allowed

            response = handler(request, *args, **kwargs)

        except Exception as exc:
            response = self.handle_exception(exc)

        self.response = self.finalize_response(request, response, *args, **kwargs)
        return self.response

    def options(self, request, *args, **kwargs):
        """
        Handler method for HTTP 'OPTIONS' request.
        """
        if self.metadata_class is None:
            return self.http_method_not_allowed(request, *args, **kwargs)
        data = self.metadata_class().determine_metadata(request, self)
        return Response(data, status=status.HTTP_200_OK)

APIView类源代码

class APIView(View):
    def dispatch(self, request, *args, **kwargs):
        """
        `.dispatch()` is pretty much the same as Django's regular dispatch,
        but with extra hooks for startup, finalize, and exception handling.
        """
        self.args = args
        self.kwargs = kwargs
        # 第一步:对request进行加工(添加数据)
        request = self.initialize_request(request, *args, **kwargs)
        self.request = request
        self.headers = self.default_response_headers  # deprecate?

        try:
            # 第二步:
            # 处理版权信息
            # 认证
            # 权限
            # 请求用户进行访问频率的限制
            self.initial(request, *args, **kwargs)

            # Get the appropriate handler method
            if request.method.lower() in self.http_method_names:
                handler = getattr(self, request.method.lower(),
                                  self.http_method_not_allowed)
            else:
                handler = self.http_method_not_allowed
            # 第三步、执行:get/post/put/delete函数
            response = handler(request, *args, **kwargs)

        except Exception as exc:
            response = self.handle_exception(exc)
        # 第四步、 对返回结果再次进行加工
        self.response = self.finalize_response(request, response, *args, **kwargs)
        return self.response

下面将对dispatch完成的功能进行详细的分析

Django REST framework 总结(附源码剖析)的更多相关文章

  1. 使用MiniProfiler给Asp.net MVC和Entity Framework号脉(附源码)

    在学习python开发框架pylons/pyramid的过程中,里面有个非常棒的页面性能监控功能,这样在开发过程中,你能清楚的知道当前页面的性能以及其它参数. 这里介绍一下如何给Asp.net MVC ...

  2. Django REST framework —— 权限组件源码分析

    在上一篇文章中我们已经分析了认证组件源码,我们再来看看权限组件的源码,权限组件相对容易,因为只需要返回True 和False即可 代码 class ShoppingCarView(ViewSetMix ...

  3. Django REST framework —— 认证组件源码分析

    我在前面的博客里已经讲过了,我们一般编写API的时候用的方式 class CoursesView(ViewSetMixin,APIView): pass 这种方式的有点是,灵活性比较大,可以根据自己的 ...

  4. Django rest framework框架——APIview源码分析

    一.什么是rest REST其实是一种组织Web服务的架构,而并不是我们想象的那样是实现Web服务的一种新的技术,更没有要求一定要使用HTTP.其目标是为了创建具有良好扩展性的分布式系统. 可用一句话 ...

  5. Django rest framework 权限操作(源码分析)

    知识回顾http://www.cnblogs.com/ctztake/p/8419059.html 这一篇是基于上一篇写的,上一篇谢了认证的具体流程,看懂了上一篇这一篇才能看懂, 当用户访问是 首先执 ...

  6. Django Rest Framework源码剖析(五)-----解析器

    一.简介 解析器顾名思义就是对请求体进行解析.为什么要有解析器?原因很简单,当后台和前端进行交互的时候数据类型不一定都是表单数据或者json,当然也有其他类型的数据格式,比如xml,所以需要解析这类数 ...

  7. Django Rest Framework源码剖析(二)-----权限

    一.简介 在上一篇博客中已经介绍了django rest framework 对于认证的源码流程,以及实现过程,当用户经过认证之后下一步就是涉及到权限的问题.比如订单的业务只能VIP才能查看,所以这时 ...

  8. Django Rest Framework源码剖析(八)-----视图与路由

    一.简介 django rest framework 给我们带来了很多组件,除了认证.权限.序列化...其中一个重要组件就是视图,一般视图是和路由配合使用,这种方式给我们提供了更灵活的使用方法,对于使 ...

  9. Django Rest Framework源码剖析(七)-----分页

    一.简介 分页对于大多数网站来说是必不可少的,那你使用restful架构时候,你可以从后台获取数据,在前端利用利用框架或自定义分页,这是一种解决方案.当然django rest framework提供 ...

随机推荐

  1. rebuild online 创建时,会话被Kill修复索引测试

    rebuild online 创建时,会话被Kill修复索引 1.0实验目的:日常运维经常create index online,但是期间被kill会导致索引再次创建失败,测试解决该问题 2.0测试流 ...

  2. [LeetCode&Python] Problem 349. Intersection of Two Arrays

    Given two arrays, write a function to compute their intersection. Example 1: Input: nums1 = [1,2,2,1 ...

  3. HDU - 5201 :The Monkey King (组合数 & 容斥)

    As everyone known, The Monkey King is Son Goku. He and his offspring live in Mountain of Flowers and ...

  4. 改变html中的内容

    $("#id").html()            获取内容 $("#id").html(xiugai)    修改内容

  5. 两道不错的递推dp

    hdoj-4055 #include <cstdio> #include <cstring> #include <iostream> #include <al ...

  6. 2017 ACM-ICPC EC-Final ShangHai 东亚洲大陆-上海

    比赛链接:传送门 Gym 101775A Chat Group(签到:待补) Gym 101775B Scapegoat(待补) Gym 101775C Traffic Light(贪心+思维) 思路 ...

  7. 栈与队列(Stack and Queue)

    1.定义 栈:后进先出(LIFO-last in first out):最后插入的元素最先出来. 队列:先进先出(FIFO-first in first out):最先插入的元素最先出来. 2.用数组 ...

  8. 《DSP using MATLAB》Problem 6.22

    代码: %% ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ %% Output In ...

  9. Python3实现生成验证码图片

    import randomfrom PIL import Image, ImageFont, ImageDrawfrom io import BytesIOfrom ttt import settin ...

  10. AangularJS过滤器详解

    (参考angular权威指南) 过滤器:   用来格式化需要展示给用户的数据: 使用过滤器的方式: (1)$scope.name=$filter("lowercase").(&qu ...