Django視圖層

'''
HttpResponse，返回字符串
render，返回html頁面，并且可以給html文件傳值
redirect，重定向

視圖函數一定會返回一個HttpResponse對象
'''

JsonResponse

from django.http import JsonResponse
user_dict = {'姓名': '123', '年齡': '123'}
return JsonResponse(user_dict, {'ensure_ascii': False})
'''ensure_ascii=True是json關鍵字參數默認值，通過向JsonResponse類傳入用于修改這個默認值的字典可以使json不再將中文字符轉為unicode編碼'''
user_hobby_list = [1,2,3,4,5,6]
return JsonResponse(user_hobby_list,safe=False)
# 將非字典類型序列化需要將safe參數值設置為False

# 前后端序列化與反序列化
javascript | python
---|---
JSON.stringify() | json.dumps()
JSON.parse() | json.loads()

form表單上傳文件及后端獲取

# form表單上傳文件類型的數據：1.method指定為post 2.enctype指定為form-data
# request.POST只能獲取普通鍵值對信息
'''
<form action="" method="post" enctype="multipart/form-data">
    <p>username:<input type="text" name="username" class="form-control"></p>
    <p>password:<input type="text" name="password" class="form-control"></p>
    <p>file:<input type="file" name="file"></p>
    <input type="submit" value="提交">
</form>

def upload_file(request):
    if request.method == 'POST':
        file_obj = request.FILES.get('file')
        with open(file_obj.name,'wb') as f: # 沒有指定文件路徑，默認保存在項目文件夾下
            for line in file_obj:
                f.write(line)

    return render(request,'form.html')
'''

request對象方法

'''
request.method
request.POST
request.GET
request.Files
request.path/request.path_info 只獲取路由部分
request.get_full_path() 獲取用戶提交url中除去ip和port后所有的路徑信息（包含?后的參數）
request.body 瀏覽器發來的原生二進制數據
'''

FBV與CBV

# 視圖層既可以是視圖函數，也可以是類
url(r'^login/', views.MyLogin.as_view(), name='app02_login'),

class MyLogin(View):
    def get(self, request):
        return HttpResponse('你提交了get請求，這個請求被django識別并交由這里的代碼處理')
    def post(self,request):
        return HttpResponse('你提交了post請求，這個請求被django識別并交由這里的代碼處理')

CBV源碼

url('login/',views.MyLogin.as_view()),
# 回顧，函數名/方法名()執行優先級最高



    @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(
                    'The method name %s is not accepted as a keyword argument '
                    'to %s().' % (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) # self = MyLogin(**initkwargs) 產生一個Mylogin對象
            self.setup(request, *args, **kwargs)
            if not hasattr(self, 'request'):
                raise AttributeError(
                    "%s instance has no 'request' attribute. Did you override "
                    "setup() and forget to call super()?" % cls.__name__
                )
            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

# as_view()內定義了閉包函數view()，并且返回值就是view函數的內存地址，在django啟動后立即執行as_view()，即得：
url('login/',views.view),