python---django的模块简便使用

一：登录操作

from django.contrib.auth import authenticate,login,logout　　#可以用来做登录验证

from django.contrib.auth.decorators import login_required　　#装饰器，用于对用户是否登录进行验证

1.简单使用：

def acc_login(request):
    error_msg = ''
    if request.method == "POST":
        username = request.POST.get("username")
        password = request.POST.get("password")
        user = authenticate(username=username,password=password)    #进行用户验证
        if user:
            login(request,user) #登录状态，添加入session, request.user = user

            return redirect(request.GET.get("next","/"))
        else:
            error_msg = "Wrong Username Or Password"

    return render(request,"login.html",{"error_msg":error_msg})

def acc_logout(request):
    logout(request) #清除session数据
    return redirect("/login.html")


from django.contrib.auth.decorators import login_required

@login_required
def dashboard(request):

    return render(request,"Sale/dashboard.html")

注意：使用@login_required需要我们配置

LOGIN_URL = "/login.html"　　#默认是在accounts/login路由下跳转

2.方法了解

（1）authenticate方法

    def authenticate(self, request, username=None, password=None, **kwargs):

        if username is None:
            username = kwargs.get(UserModel.USERNAME_FIELD)
        try:
            user = UserModel._default_manager.get_by_natural_key(username)　　#根据用户名获取用户对象
        except UserModel.DoesNotExist:
            # Run the default password hasher once to reduce the timing
            # difference between an existing and a non-existing user (#20760).
            UserModel().set_password(password)
        else:
            if user.check_password(password) and self.user_can_authenticate(user):　　#根据密码进行登录验证，以及获取用户的操作权限
                return user

UserModel = get_user_model()

def get_user_model():　　#返回用户表对象，对象由AUTH_USER_MODEL指定，默认是auth.User默认数据表，我们可以在自己的setting文件中进行覆盖
    """
    Returns the User model that is active in this project.
    """
    return django_apps.get_model(settings.AUTH_USER_MODEL, require_ready=False)

（2）login方法

def login(request, user, backend=None):

def login(request, user, backend=None):
    """
    Persist a user id and a backend in the request. This way a user doesn't
    have to reauthenticate on every request. Note that data set during
    the anonymous session is retained when the user logs in.
    """
    session_auth_hash = ''
    if user is None:
        user = request.user
    if hasattr(user, 'get_session_auth_hash'):
        session_auth_hash = user.get_session_auth_hash()

    if SESSION_KEY in request.session:
        if _get_user_session_key(request) != user.pk or (
                session_auth_hash and
                not constant_time_compare(request.session.get(HASH_SESSION_KEY, ''), session_auth_hash)):
            # To avoid reusing another user's session, create a new, empty
            # session if the existing session corresponds to a different
            # authenticated user.
            request.session.flush()
    else:
        request.session.cycle_key()

    try:
        backend = backend or user.backend
    except AttributeError:
        backends = _get_backends(return_tuples=True)
        if len(backends) == 1:
            _, backend = backends[0]
        else:
            raise ValueError(
                'You have multiple authentication backends configured and '
                'therefore must provide the `backend` argument or set the '
                '`backend` attribute on the user.'
            )

    request.session[SESSION_KEY] = user._meta.pk.value_to_string(user)
    request.session[BACKEND_SESSION_KEY] = backend
    request.session[HASH_SESSION_KEY] = session_auth_hash
    if hasattr(request, 'user'):
        request.user = user
    rotate_token(request)
    user_logged_in.send(sender=user.__class__, request=request, user=user)

（3）logout方法

def logout(request):

def logout(request):
    """
    Removes the authenticated user's ID from the request and flushes their
    session data.
    """
    # Dispatch the signal before the user is logged out so the receivers have a
    # chance to find out *who* logged out.
    user = getattr(request, 'user', None)
    if hasattr(user, 'is_authenticated') and not user.is_authenticated:
        user = None
    user_logged_out.send(sender=user.__class__, request=request, user=user)

    # remember language choice saved to session
    language = request.session.get(LANGUAGE_SESSION_KEY)

    request.session.flush()

    if language is not None:
        request.session[LANGUAGE_SESSION_KEY] = language

    if hasattr(request, 'user'):
        from django.contrib.auth.models import AnonymousUser
        request.user = AnonymousUser()

（4）login_required方法

def login_required(function=None, redirect_field_name=REDIRECT_FIELD_NAME, login_url=None):#function是我们装饰的函数名，redirect_field_name是跳转时所带的参数，默认next

    """
    Decorator for views that checks that the user is logged in, redirecting
    to the log-in page if necessary.
    """
    actual_decorator = user_passes_test(
        lambda u: u.is_authenticated,
        login_url=login_url,
        redirect_field_name=redirect_field_name
    )
    if function:
        return actual_decorator(function)
    return actual_decorator

def user_passes_test(test_func, login_url=None, redirect_field_name=REDIRECT_FIELD_NAME):
    """
    Decorator for views that checks that the user passes the given test,
    redirecting to the log-in page if necessary. The test should be a callable
    that takes the user object and returns True if the user passes.
    """

    def decorator(view_func):
        @wraps(view_func, assigned=available_attrs(view_func))
        def _wrapped_view(request, *args, **kwargs):
            if test_func(request.user):
                return view_func(request, *args, **kwargs)
            path = request.build_absolute_uri()
            resolved_login_url = resolve_url(login_url or settings.LOGIN_URL)
            # If the login url is the same scheme and net location then just
            # use the path as the "next" url.
            login_scheme, login_netloc = urlparse(resolved_login_url)[:2]
            current_scheme, current_netloc = urlparse(path)[:2]
            if ((not login_scheme or login_scheme == current_scheme) and
                    (not login_netloc or login_netloc == current_netloc)):
                path = request.get_full_path()
            from django.contrib.auth.views import redirect_to_login
            return redirect_to_login(
                path, resolved_login_url, redirect_field_name)
        return _wrapped_view
    return decorator

 二：csrf的多种使用方法

from django.views.decorators.csrf import csrf_exempt

1.需求分析

当我们需要对某一个view方法去掉csrf_token验证时。总不至于去注释掉所有的csrf验证吧

# 'django.middleware.csrf.CsrfViewMiddleware',

那么我们需要去取消某一个方法的csrf验证

2.实现代码

1.FBV:直接使用装饰器方法

@csrf_exempt
def asset(request):
    pass

2.CBV:需要再去引入一个模块（其实也可以直接使用）

from django.utils.decorators import method_decorator

class AssetView(View):
    @method_decorator(csrf_exempt)
    def dispatch(self, request, *args, **kwargs):
        return super(AssetView, self).dispatch(request, *args, **kwargs)

    def post(self,request,*args,**kwargs):
　　　　  pass

　　 def put(self,request,*args,**kwargs):
　　　　  pass

其中dispatch()方法：作用是将任务分发到正确的方法上。因为需要过滤掉csrf的方法不止post，还有put等，所以在dispatch中过滤掉csrf，那么在其他的方法上可以不用去管

3.在url中进行过滤

from django.conf.urls import url
from API import views as v1
from django.views.decorators.csrf import csrf_exempt


urlpatterns = [
    url(r'^asset',csrf_exempt(v1.AssetView.as_view())),  
]

 三：import导入的多种方法（用于反射）

1.一般导入模块直接使用import

import 模块　　#一般我们是直接使用import导入对应模块

from 包 import 模块　　#多层导入 

2.需求：现有字符串代表各个模块，如何通过反射获取该模块

（1）使用__import__

__import__("模块")　　

__import__("层一.层二.层三.模块",fromlist=True)　#对于多层，我们使用.连接。注意：fromlist需要添加为True，不然只会导入层一，调用的使用我们还要一级一级向下找，不方便

def __import__(name, globals=None, locals=None, fromlist=(), level=0): # real signature unknown; restored from __doc__

When importing a module from a package, note that __import__('A.B', ...)
returns package A when fromlist is empty, but its submodule B when
fromlist is not empty.

package：test3    --->   包下面有t2.py文件，定义test2方法
无fromlist:
md = __import__("test3.t2")
md.t2.test2()  #test2


有fromlist
md = __import__("test3.t2",fromlist=True)
md.test2()

（2）使用importlib.import_module

def import_module(name, package=None):
#如果是相对导入的话，第二个参数是需要的

    The 'package' argument is required when performing a relative import. It
    specifies the package to use as the anchor point from which to resolve the
    relative import to an absolute import.

md = importlib.import_module("test3.t2")
md.test2()　　#test2

md = importlib.import_module(".t2","test3")　　#.t2代表时相对于test3下的相对路径，就是相当于将前后连接test3.t2
md.test2()

md = importlib.import_module("test3.t1.t11")
md.test11()

md = importlib.import_module(".t1.t11","test3")
md.test11()

#test11
#test11