drf认证源码分析

补充：

一、django中间件之路由斜杠的自动添加源码

　　其实我们每次在写路由的时候，如果在路由层给他设置的是加/，但实际上我们在浏览器中输入的时候并没有加/发现也能调用，前面说了是浏览器内部走了重定向，所以会自动的给我们加上/匹配，但是难道我们就不好奇究竟是谁让他内部走了重定向吗？

　　想想，它在第一次来的时候没有匹配上路由就会直接重定向，那他肯定是还没走到视图层，在想一想django的请求生命周期，来了请求之后，进入django内部是不是要先经过什么？好像是中间件！！那就必然和中间件有某种关系，然后我们在去查看中间件的源码的时候，发现了果然如此！

# 查看中间件源码的方式
from django.middleware.common import CommonMiddleware

MIDDLEWARE = [
    'django.middleware.security.SecurityMiddleware',
    'django.contrib.sessions.middleware.SessionMiddleware',
    # 内部重定向，刚开始没有斜杠会自动加斜杠，内部走了301重定向
    'django.middleware.common.CommonMiddleware',
    # 'django.middleware.csrf.CsrfViewMiddleware',
    'django.contrib.auth.middleware.AuthenticationMiddleware',
    'django.contrib.messages.middleware.MessageMiddleware',
    'django.middleware.clickjacking.XFrameOptionsMiddleware',
]

我们看了一下是CommonMiddleware这个中间件做的鬼，那我们就点进去看看！

class CommonMiddleware(MiddlewareMixin):
    """
    "Common" middleware for taking care of some basic operations:

        - Forbids access to User-Agents in settings.DISALLOWED_USER_AGENTS

        - URL rewriting: Based on the APPEND_SLASH and PREPEND_WWW settings,
          this middleware appends missing slashes and/or prepends missing
          "www."s.

            - If APPEND_SLASH is set and the initial URL doesn't end with a
              slash, and it is not found in urlpatterns, a new URL is formed by
              appending a slash at the end. If this new URL is found in
              urlpatterns, then an HTTP-redirect is returned to this new URL;
              otherwise the initial URL is processed as usual.

          This behavior can be customized by subclassing CommonMiddleware and
          overriding the response_redirect_class attribute.

        - ETags: If the USE_ETAGS setting is set, ETags will be calculated from
          the entire page content and Not Modified responses will be returned
          appropriately. USE_ETAGS is deprecated in favor of
          ConditionalGetMiddleware.
    """

    response_redirect_class = http.HttpResponsePermanentRedirect  # 点进去看看，发现内部走了重定向

class HttpResponsePermanentRedirect(HttpResponseRedirectBase):
    status_code = 301

发现在内部其实是走了301重定向

二、django模型表之一对一关系源码

入口

class Book(models.Model):
    title = models.CharField(max_length=32)
    price = models.IntegerField()
    # 就是它