Django视图中CSS 3D翻转卡片状态的持久化与控制

from django.shortcuts import render, redirect
from django.contrib.auth import authenticate, login
from django.contrib import messages
from django.views import View
from django.contrib.auth.forms import UserCreationForm

class LoginRegisterView(View): # 建议类名更具描述性

    def get(self, request):
        form = UserCreationForm()
        if "sign-in" in request.GET:
            username = request.GET.get("username")
            password = request.GET.get("password")
            # 传递 request 对象给 authenticate
            user = authenticate(request, username=username, password=password)
            if user is not None:
                login(request, user)
                return redirect('/admin')
            else:
                messages.info(request, 'Login attempt failed.')
                return redirect('login_register')

        # 从会话中获取 'using_backcard' 状态，如果不存在则默认为 False
        # 使用 .pop() 方法确保状态只被读取一次后即从会话中移除
        using_backcard = request.session.pop('using_backcard', False)

        return render(
            request,
            'index.html',
            {
                'form': form,
                'using_backcard': using_backcard, # 将状态传递给模板上下文
            }
        )

    def post(self, request):
        if "sign-up" in request.POST:
            form = UserCreationForm(request.POST)
            if form.is_valid():
                user = form.save() # 保存新创建的用户
                login(request, user) # 登录新创建的用户
                messages.success(request, 'Account has been created successfully')
                # 在重定向前，将 'using_backcard' 标志设置为 True 存储到会话中
                request.session['using_backcard'] = True
                return redirect('login_register')
            else:
                # 如果表单验证失败，直接渲染当前页面，并传递错误信息
                messages.error(request, form.errors)
                # 此时通常不显示背面，因为用户需要重新填写表单
                return render(request, 'index.html', {'form': form, 'using_backcard': False})
        # 处理其他 POST 请求（如果存在）
        return render(request, 'index.html', {'form': UserCreationForm()})

<input class="checkbox" type="checkbox" id="reg-log" name="reg-log" {% if using_backcard %} checked {% endif %}/>

# views.py (示例，如果不需要重定向)
class LoginRegisterView(View):
    # ... get 方法不变 ...

    def post(self, request):
        if "sign-up" in request.POST:
            form = UserCreationForm(request.POST)
            if form.is_valid():
                user = form.save()
                login(request, user)
                messages.success(request, 'Account has been created successfully')
                # 直接渲染，并传递状态
                return render(request, 'index.html', {'form': form, 'using_backcard': True})
            else:
                messages.error(request, form.errors)
                # 表单验证失败时，通常显示正面
                return render(request, 'index.html', {'form': form, 'using_backcard': False})
        return render(request, 'index.html', {'form': UserCreationForm()})