Django用户注册时如何将邮箱转为小写并实现自动登录？

你的代码里有两个关键问题导致注册后无法自动登录：

1. 用户对象未实际保存到数据库 #

在处理推荐注册的分支中，你写了instance.save，这里缺少括号()，导致用户对象并未被真正保存到数据库。后续依赖该用户的操作都会出现异常，直接影响登录流程。

2. 认证时使用了原始大小写的邮箱 #

你将数据库中的邮箱转换为小写，但认证时用的是form.cleaned_data.get('email')获取的用户原始输入（可能包含大写）。Django的authenticate默认会严格匹配用户名/邮箱的大小写，这就导致数据库里的小写邮箱和输入的原邮箱无法匹配，认证失败。

修正后的完整代码 #

def registerRef(request, *args, **kwargs):
    if request.user.is_authenticated:
        return redirect('core:index')

    profile_id = request.session.get('ref_profile')
    print('profile_id', profile_id)
    try:
        signup_point = SignUpPoint.objects.get()
    except:
        signup_point = None 

    code = str(kwargs.get('ref_code'))
    try:
        profile = Profile.objects.get(code=code)
        profile_user = Profile.objects.get(code=code)
        request.session['ref_profile'] = profile.id
        print('Referer Profile:', profile.id)
    except:
        pass
    print("Session Expiry Date:" + str(request.session.get_expiry_age()))

    form = UserRegisterForm(request.POST or None)
    if form.is_valid():
        if profile_id is not None:
            recommended_by_profile = Profile.objects.get(id=profile_id)
            ref_earn = InvestmentPackageID.objects.get()

            instance = form.save(commit=False)
            # 转换邮箱和用户名到小写
            instance.email = instance.email.lower()
            instance.username = instance.username.lower()
            # 修复：添加括号执行保存操作
            instance.save()
            # 直接使用已保存的instance，避免重复查询数据库
            registered_user = instance
            registered_profile = Profile.objects.get(user=registered_user)
            registered_profile.recommended_by = recommended_by_profile.user
            
            my_recomended = Profile.objects.filter(recommended_by=profile_user.user).values_list('user__id', flat=True)
            print(my_recomended)
            
            registered_profile.save()
            profile = Profile.objects.get(user=registered_user)
            profile.earning_point = signup_point.signup_point
            profile.main_all_earning += signup_point.signup_point
            profile.save()

            # 简化条件判断写法
            if recommended_by_profile.level_1 and not recommended_by_profile.level_6 and not recommended_by_profile.level_5 and not recommended_by_profile.level_4 and not recommended_by_profile.level_3 and not recommended_by_profile.level_2:
                recommended_by_profile.referral_point += ref_earn.ref_earn1
                recommended_by_profile.main_all_earning += ref_earn.ref_earn1
                recommended_by_profile.save()
                        
            else:
                recommended_by_profile.referral_point += 500
                recommended_by_profile.main_all_earning += 500
                recommended_by_profile.save()
                ActiveRefEarning.objects.create(user=registered_user, active_ref_earning_owner=recommended_by_profile.user, active_ref_earning=500)             
            
            profile.save()
            recommended_by_profile.save()
        
        else:
            # 非推荐注册分支也统一转换邮箱和用户名到小写
            instance = form.save(commit=False)
            instance.email = instance.email.lower()
            instance.username = instance.username.lower()
            instance.save()
            registered_user = instance
            profile = Profile.objects.get(user=registered_user)
            profile.earning_point = signup_point.signup_point
            profile.main_all_earning += signup_point.signup_point
            profile.save()

        # 修复：使用数据库中存储的小写邮箱进行认证
        username = registered_user.email
        password = form.cleaned_data.get('password1')
        user = authenticate(username=username, password=password)
        # 添加认证成功判断，避免异常
        if user is not None:
            login(request, user)
            NewsLetter.objects.create(email=username)
            messages.success(request, f"Hi {request.user.username}, {signup_point.signup_message}")

        return redirect('core:index')
    context = {'form':form}
    return render(request, 'userauths/sign-up.html', context)

额外优化说明 #

1. 统一两个分支的处理逻辑，非推荐注册分支也转换邮箱和用户名到小写，保持数据一致性
2. 直接使用保存后的instance作为registered_user，减少不必要的数据库查询
3. 简化条件判断语句，提升代码可读性
4. 添加user is not None的判断，避免认证失败时调用login抛出异常

内容的提问来源于stack exchange，提问作者Destiny Franks