Restrramework源码(包含组件)分析

1.总体流程分析

rest_framework/view.py

请求通过url分发，触发as_view方法，该方法在ViewSetMixin类下

点进去查看as_view源码说明，可以看到它在正常情况下是zhix执行了self.dispatch(request, *args, **kwargs)方法

 @classonlymethod
    def as_view(cls, actions=None, **initkwargs):
        """
        Because of the way class based views create a closure around the
        instantiated view, we need to totally reimplement `.as_view`,
        and slightly modify the view function that is created and returned.
        """
        # The suffix initkwarg is reserved for displaying the viewset type.
        # eg. 'List' or 'Instance'.
        cls.suffix = None

        # The detail initkwarg is reserved for introspecting the viewset type.
        cls.detail = None

        # Setting a basename allows a view to reverse its action urls. This
        # value is provided by the router through the initkwargs.
        cls.basename = None

        # actions must not be empty
        if not actions:
            raise TypeError("The `actions` argument must be provided when "
                            "calling `.as_view()` on a ViewSet. For example "
                            "`.as_view({'get': 'list'})`")

        # sanitize keyword arguments
        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" % (
                    cls.__name__, key))

        def view(request, *args, **kwargs):
            self = cls(**initkwargs)
            # We also store the mapping of request methods to actions,
            # so that we can later set the action attribute.
            # eg. `self.action = 'list'` on an incoming GET request.
            self.action_map = actions

            # Bind methods to actions
            # This is the bit that's different to a standard view
            for method, action in actions.items():
                handler = getattr(self, action)
                setattr(self, method, handler)

            if hasattr(self, 'get') and not hasattr(self, 'head'):
                self.head = self.get

            self.request = request
            self.args = args
            self.kwargs = kwargs

            # And continue as usual
            return self.dispatch(request, *args, **kwargs)

        # 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=())

        # We need to set these on the view function, so that breadcrumb
        # generation can pick out these bits of information from a
        # resolved URL.
        view.cls = cls
        view.initkwargs = initkwargs
        view.suffix = initkwargs.get('suffix', None)
        view.actions = actions
        return csrf_exempt(view)

View Code

　通过查找可以看到dispatch方法在这个class APIView(View)类里

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

从源码介绍我们可以看到，相关的组件，这里做了全局配置

请求到dispatch后，做了封装request和认证两件事，

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
    # 对原始request进行加工，封装request
    request = self.initialize_request(request, *args, **kwargs)
    self.request = request
    self.headers = self.default_response_headers  # deprecate?

    try:
        # 认证
        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

self.initialize_request(request, *args, **kwargs)：--->封装request

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
)

这里它返回了初始请求对象Request，它继承了Request类

其中的几个方法：

这里要说明的是最终的authentication_classes它到了全局去查找

接下来执行self.initial(request, *args, **kwargs)，我们点进去，这是运行之前需要执行的方法

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)

调用方法处理程序之前，依次执行了四个restframework给我们的组件，版本管理，用户认证，权限，节流

这里自上而下执行，版本就没啥说了，先来看用户认证：

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

需要说明的是，这里的request其实是封装之后的request，读者一般第一次看到这里可能会比较纳闷，request.user是啥，其实这里的user调用了property属性

这里的user方法说明，返回与当前请求关联的用户，由提供给请求的身份验证类进行身份验证。

对于这里的self._authenticate（）：

 def _authenticate(self):
        """
        Attempt to authenticate the request using each authentication instance
        in turn.
        """
        for authenticator in self.authenticators:
            try:
                user_auth_tuple = authenticator.authenticate(self)
            except exceptions.APIException:
                self._not_authenticated()
                raise

            if user_auth_tuple is not None:
                self._authenticator = authenticator
                self.user, self.auth = user_auth_tuple
                return

        self._not_authenticated()

这里循环我们的authenticator，如果有返回值则执行authenticate(self)方法，最终返回的是个元祖，其中有user,token两个值

如果上面方法执行抛出异常，则执行self._not_authenticated()方法，设置表示未经身份验证的请求的authenticator，user和authtoken。默认为None，AnonymousUser＆None。

整个restframework声明周期在这里在说明一下：

　　发送请求-->Django的wsgi-->中间件-->路由系统_执行CBV的as_view()，就是执行内部的dispath方法-->在执行dispath之前，有版本分析和渲染器

　　在dispath内，对request封装-->版本-->认证-->权限-->限流-->视图-->如果视图用到缓存( request.data or request.query_params )就用到了解析器-->视图处理数据，用到了序列化(对数据进行序列化或验证) -->视图返回数据可以用到分页

2.用户登录认证

对于rest_framework给我们提供的这个内置认证组件

在authentication.py文件下包含的认证类：

包含了这么多，但我们其实也是基于上面的BaseAuthentication来重写我们的用户认证，先来看看源码：

class BaseAuthentication(object):
    """
    All authentication classes should extend BaseAuthentication.
    """

    def authenticate(self, request):
        """
        Authenticate the request and return a two-tuple of (user, token).
        """
        raise NotImplementedError(".authenticate() must be overridden.")

    def authenticate_header(self, request):
        """
        Return a string to be used as the value of the `WWW-Authenticate`
        header in a `401 Unauthenticated` response, or `None` if the
        authentication scheme should return `403 Permission Denied` responses.
        """
        pass

说了一大堆东西，最终也只是解释性说明，还是需要我们自己来写相关的用户认证，官方只给我们提供了这么一个框架而已

这里相关具体使用方法可以参考我的这篇博客

具体流程：

　　创建认证类，继承BaseAuthentication，重写authenticate方法和authenticate_header方法

　　对于authenticate()方法的返回值：

　　　　可以返回 raise AuthenticationFailed({'code':1000,'error':'认证失败'})　　　需要导入：from rest_framework.exceptions import AuthenticationFailed

　　　　可以返回一个元祖 return (token_obj.user, token_obj)

　　　　　　　　　　token_obj.user赋值给了request.user

　　　　　　　　　　token_obj赋值给了request.auth

　　这里还要注意它的使用，可以在全局配制，亦可以在局部配制：

　　　　　　对于局部，直接在上面加上authentication_classes = [BaseAuthentication,]

　　　　　　对于全局，需要在我们方setting下进行restframework全局设置

REST_FRAMEWORK = {
    "DEFAULT_AUTHENTICATION_CLASSES":['API.utils.auth.Authentication',]
}

3. 权限认证

permissions.py：

class BasePermission(object):
    """
    A base class from which all permission classes should inherit.
    """

    def has_permission(self, request, view):
        """
        Return `True` if permission is granted, `False` otherwise.
        """
        return True

    def has_object_permission(self, request, view, obj):
        """
        Return `True` if permission is granted, `False` otherwise.
        """
        return True

这里BasePermission类给我们提供了has_permission方法，和has_has_object_permission两个方法，都是让我们自己重写，最终返回值都是都是布尔值，以此判定是否具有权限

我们需要编写自己的类，来继承BasePermission

使用样式伪代码：

class TestView(APIView):
    # 认证的动作是由request.user触发
    authentication_classes = [TestAuthentication, ]

    # 权限
    # 循环执行所有的权限
    permission_classes = [TestPermission, ]

    def get(self, request, *args, **kwargs):
        # self.dispatch
        print(request.user)
        print(request.auth)
        return Response('GET请求，响应内容')

    def post(self, request, *args, **kwargs):
        return Response('POST请求，响应内容')

以上是在局部配置，全局配置只需在配置文件中写入即可

细节详情参考博客

4.节流

throttling.py：

class BaseThrottle(object):
    """
    Rate throttling of requests.
    """

    def allow_request(self, request, view):
        """
        Return `True` if the request should be allowed, `False` otherwise.
        """
        raise NotImplementedError('.allow_request() must be overridden')

    def get_ident(self, request):
        """
        Identify the machine making the request by parsing HTTP_X_FORWARDED_FOR
        if present and number of proxies is > 0. If not use all of
        HTTP_X_FORWARDED_FOR if it is available, if not use REMOTE_ADDR.
        """
        xff = request.META.get('HTTP_X_FORWARDED_FOR')
        remote_addr = request.META.get('REMOTE_ADDR')
        num_proxies = api_settings.NUM_PROXIES

        if num_proxies is not None:
            if num_proxies == 0 or xff is None:
                return remote_addr
            addrs = xff.split(',')
            client_addr = addrs[-min(num_proxies, len(addrs))]
            return client_addr.strip()

        return ''.join(xff.split()) if xff else remote_addr

    def wait(self):
        """
        Optionally, return a recommended number of seconds to wait before
        the next request.
        """
        return None

可以看出这是一个父类，它只提供了返回值，这里具体就是代码的编写了，怎么才能做到时间段内的固定访问次数呢，肯定需要用到时间模块以及该用户的ip了，通过

RECORD = {
    '用户IP': [12312139, 12312135, 12312133, ]
}
的形式来做判断
代码演示：

from rest_framework.throttling import BaseThrottle
import time
 
D = {}  # {'127.0.0.1': [1533302442, 1533302439,...]}
 
class MyThrottle(BaseThrottle):
    # 点进源码直接看当中携带的参数
    def allow_request(self, request, view):
        """
        Return `True` if the request should be allowed, `False` otherwise.
        """
        # 访问当前IP
        ip = request.META.get('REMOTE_ADDR')
        print(ip)
        now = time.time()
        if ip not in D:
            D[ip] = []  # 初始化一个空的访问历史列表
 
        history = D[ip]
        # 当历史列表中有元素，并且当前时间戳减去最后一个元素的时间戳大于10
        while history and (now - history[-1]) > 10:
            history.pop()
        # 判断最近10秒内的访问次数是否超过了阈值（3次）
        if len(history) >= 3:
            return False
        else:
            # 把这一次的访问时间加到访问历史列表的第一位
            D[ip].insert(0,now)
            return True

具体操作链接

这里也能使用它内部封装好的子类进行操作

class SimpleRateThrottle(BaseThrottle):
    """
    A simple cache implementation, that only requires `.get_cache_key()`
    to be overridden.

    The rate (requests / seconds) is set by a `rate` attribute on the View
    class.  The attribute is a string of the form 'number_of_requests/period'.

    Period should be one of: ('s', 'sec', 'm', 'min', 'h', 'hour', 'd', 'day')

    Previous request information used for throttling is stored in the cache.
    """
    cache = default_cache
    timer = time.time
    cache_format = 'throttle_%(scope)s_%(ident)s'
    scope = None
    THROTTLE_RATES = api_settings.DEFAULT_THROTTLE_RATES

    def __init__(self):
        if not getattr(self, 'rate', None):
            self.rate = self.get_rate()
        self.num_requests, self.duration = self.parse_rate(self.rate)

    def get_cache_key(self, request, view):
        """
        Should return a unique cache-key which can be used for throttling.
        Must be overridden.

        May return `None` if the request should not be throttled.
        """
        raise NotImplementedError('.get_cache_key() must be overridden')

    def get_rate(self):
        """
        Determine the string representation of the allowed request rate.
        """
        if not getattr(self, 'scope', None):
            msg = ("You must set either `.scope` or `.rate` for '%s' throttle" %
                   self.__class__.__name__)
            raise ImproperlyConfigured(msg)

        try:
            return self.THROTTLE_RATES[self.scope]
        except KeyError:
            msg = "No default throttle rate set for '%s' scope" % self.scope
            raise ImproperlyConfigured(msg)

    def parse_rate(self, rate):
        """
        Given the request rate string, return a two tuple of:
        <allowed number of requests>, <period of time in seconds>
        """
        if rate is None:
            return (None, None)
        num, period = rate.split('/')
        num_requests = int(num)
        duration = {'s': 1, 'm': 60, 'h': 3600, 'd': 86400}[period[0]]
        return (num_requests, duration)

    def allow_request(self, request, view):
        """
        Implement the check to see if the request should be throttled.

        On success calls `throttle_success`.
        On failure calls `throttle_failure`.
        """
        if self.rate is None:
            return True

        self.key = self.get_cache_key(request, view)
        if self.key is None:
            return True

        self.history = self.cache.get(self.key, [])
        self.now = self.timer()

        # Drop any requests from the history which have now passed the
        # throttle duration
        while self.history and self.history[-1] <= self.now - self.duration:
            self.history.pop()
        if len(self.history) >= self.num_requests:
            return self.throttle_failure()
        return self.throttle_success()

    def throttle_success(self):
        """
        Inserts the current request's timestamp along with the key
        into the cache.
        """
        self.history.insert(0, self.now)
        self.cache.set(self.key, self.history, self.duration)
        return True

    def throttle_failure(self):
        """
        Called when a request to the API has failed due to throttling.
        """
        return False

    def wait(self):
        """
        Returns the recommended next request time in seconds.
        """
        if self.history:
            remaining_duration = self.duration - (self.now - self.history[-1])
        else:
            remaining_duration = self.duration

        available_requests = self.num_requests - len(self.history) + 1
        if available_requests <= 0:
            return None

        return remaining_duration / float(available_requests)

只用它的好处在于省去了大量代码，只要实现逻辑层相关业务即可

自己写的throttle.py：

from rest_framework.throttling import SimpleRateThrottle

class VisitThrottle(SimpleRateThrottle):
    '''匿名用户60s只能访问三次（根据ip）'''
    scope = 'OP'   #这里面的值，自己随便定义，settings里面根据这个值配置Rate

    def get_cache_key(self, request, view):
        #通过ip限制节流
        return self.get_ident(request)    # 远程IP地址

class UserThrottle(SimpleRateThrottle):
    '''登录用户60s可以访问10次'''
    scope = 'OA'    #这里面的值，自己随便定义，settings里面根据这个值配置Rate

    def get_cache_key(self, request, view):
        return request.user.username    # 返回用户名

setting.py下的配制

REST_FRAMEWORK = {
    #节流
    "DEFAULT_THROTTLE_CLASSES":['API.utils.throttle.UserThrottle'],   #全局配置，登录用户节流限制（10/m）
    "DEFAULT_THROTTLE_RATES":{
        'OP':'3/m',         #没登录用户3/m，
        'OA':'10/m',    #登录用户10/m，
    }
}