Django 注冊表未更改並保存到數據庫

Question

我正在嘗試創建一個自定義表單，例如用戶也可以在其中輸入他的姓名，但我遇到了一個問題，當注冊完成時，名稱沒有保存，我無法在模板上顯示它。 這是代碼：

視圖.py

def sign_up(request):
form = forms.SignUpForm()

if request.method == 'POST':
    form = forms.SignUpForm(request.POST)

    if form.is_valid():
        email = form.cleaned_data.get('email').lower()

        user = form.save(commit=False)
        user.username = email
        user.save()

        login(request, user)
        return redirect('/')

return render(request, 'sign_up.html', {
    'form': form
})

forms.py

class SignUpForm(UserCreationForm):
email = forms.EmailField(max_length=250)
first_name = forms.CharField(max_length=150)
last_name = forms.CharField(max_length=150)

class Meta:
     model = User
     fields = ('email', 'first_name', 'last_name', 'password1', 'password2')

def clean_email(self):
     email = self.cleaned_data['email'].lower()
     if User.objects.filter(email=email):
         raise ValidationError("This email address already exists.")
     return email

sign_up.html

<form method="POST">
       {% csrf_token %}
       {% bootstrap_form form %}
       <button type="submit" class="btn btn-warning btn-block">Sign Up</button>
       <p class="text-center mt-3" >
       Already have an account? <a href="/sign-in/?next={{ request.GET.next }}"><b>Sign In</b></a>
   </p>
</form>

html 還向我顯示了用戶名，我想刪除並使用 email 地址登錄。 但是沒有任何東西保存在數據庫中......