restful framework之频率组件

一、频率简介

为了控制用户对某个url请求的频率，比如，一分钟以内，只能访问三次

二、自定义频率类、自定义频率规则

自定义的逻辑

#（1）取出访问者ip
# （2）判断当前ip不在访问字典里，添加进去，并且直接返回True,表示第一次访问，在字典里，继续往下走
# （3）循环判断当前ip的列表，有值，并且当前时间减去列表的最后一个时间大于60s，把这种数据pop掉，这样列表中只有60s以内的访问时间，
# （4）判断，当列表小于3，说明一分钟以内访问不足三次，把当前时间插入到列表第一个位置，返回True，顺利通过
# （5）当大于等于3，说明一分钟内访问超过三次，返回False验证失败

代码实现：

class MyThrottles():
    VISIT_RECORD = {}
    def __init__(self):
        self.history=None
    def allow_request(self,request, view):
        #（1）取出访问者ip
        # print(request.META)
        ip=request.META.get('REMOTE_ADDR')
        import time
        ctime=time.time()
        # （2）判断当前ip不在访问字典里，添加进去，并且直接返回True,表示第一次访问
        if ip not in self.VISIT_RECORD:
            self.VISIT_RECORD[ip]=[ctime,]
            return True
        self.history=self.VISIT_RECORD.get(ip)
        # （3）循环判断当前ip的列表，有值，并且当前时间减去列表的最后一个时间大于60s，把这种数据pop掉，这样列表中只有60s以内的访问时间，
        while self.history and ctime-self.history[-1]>60:
            self.history.pop()
        # （4）判断，当列表小于3，说明一分钟以内访问不足三次，把当前时间插入到列表第一个位置，返回True，顺利通过
        # （5）当大于等于3，说明一分钟内访问超过三次，返回False验证失败
        if len(self.history)<3:
            self.history.insert(0,ctime)
            return True
        else:
            return False
    def wait(self):
        import time
        ctime=time.time()
        return 60-(ctime-self.history[-1])

三、内置频率类及局部使用

写一个类，继承自SimpleRateThrottle，（根据ip限制）问：要根据用户现在怎么写

from rest_framework.throttling import SimpleRateThrottle
class VisitThrottle(SimpleRateThrottle):
    scope = 'luffy'
    def get_cache_key(self, request, view):
        return self.get_ident(request)

在setting里配置：（一分钟访问三次）

REST_FRAMEWORK = {
    'DEFAULT_THROTTLE_RATES':{
        'luffy':'3/m'
    }
}

在视图类里使用

throttle_classes = [MyThrottles,]

错误信息的中文提示：

class Course(APIView):
    authentication_classes = [TokenAuth, ]
    permission_classes = [UserPermission, ]
    throttle_classes = [MyThrottles,]

    def get(self, request):
        return HttpResponse('get')

    def post(self, request):
        return HttpResponse('post')
    def throttled(self, request, wait):
        from rest_framework.exceptions import Throttled
        class MyThrottled(Throttled):
            default_detail = '傻逼啊'
            extra_detail_singular = '还有 {wait} second.'
            extra_detail_plural = '出了 {wait} seconds.'
        raise MyThrottled(wait)

内置频率限制类：

BaseThrottle是所有类的基类：方法：def get_ident(self, request)获取标识，其实就是获取ip，自定义的需要继承它

AnonRateThrottle：未登录用户ip限制，需要配合auth模块用

SimpleRateThrottle：重写此方法，可以实现频率现在，不需要咱们手写上面自定义的逻辑

UserRateThrottle:登录用户频率限制，这个得配合auth模块来用

ScopedRateThrottle：应用在局部视图上的（忽略）

四、内置全局类及全局使用

REST_FRAMEWORK = {
    'DEFAULT_THROTTLE_CLASSES':['app01.utils.VisitThrottle',],
    'DEFAULT_THROTTLE_RATES':{
        'luffy':'3/m'
    }
}

五、源码分析

def check_throttles(self, request):
        for throttle in self.get_throttles():
            if not throttle.allow_request(request, self):
                self.throttled(request, throttle.wait())
    def throttled(self, request, wait):
        #抛异常，可以自定义异常，实现错误信息的中文显示
        raise exceptions.Throttled(wait)

SimpleRateThrottle源码分析

class SimpleRateThrottle(BaseThrottle):
    # 咱自己写的放在了全局变量，他的在django的缓存中
    cache = default_cache
    # 获取当前时间，跟咱写的一样
    timer = time.time
    # 做了一个字符串格式化，
    cache_format = 'throttle_%(scope)s_%(ident)s'
    scope = None
    # 从配置文件中取DEFAULT_THROTTLE_RATES，所以咱配置文件中应该配置，否则报错
    THROTTLE_RATES = api_settings.DEFAULT_THROTTLE_RATES

    def __init__(self):
        if not getattr(self, 'rate', None):
            # 从配置文件中找出scope配置的名字对应的值，比如咱写的‘3/m’,他取出来
            self.rate = self.get_rate()
        #     解析'3/m',解析成 3      m
        self.num_requests, self.duration = self.parse_rate(self.rate)
    # 这个方法需要重写
    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):
        if not getattr(self, 'scope', None):
            msg = ("You must set either `.scope` or `.rate` for '%s' throttle" %
                   self.__class__.__name__)
            raise ImproperlyConfigured(msg)

        try:
            # 获取在setting里配置的字典中的之，self.scope是 咱写的luffy
            return self.THROTTLE_RATES[self.scope]
        except KeyError:
            msg = "No default throttle rate set for '%s' scope" % self.scope
            raise ImproperlyConfigured(msg)
    # 解析 3/m这种传参
    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)
        # 只取了第一位，也就是 3/mimmmmmmm也是代表一分钟
        duration = {'s': 1, 'm': 60, 'h': 3600, 'd': 86400}[period[0]]
        return (num_requests, duration)
    # 逻辑跟咱自定义的相同
    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()
    # 成功返回true，并且插入到缓存中
    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
    # 失败返回false
    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)