如果form.is_valid（）返回False，因为您使用username变量创建用户，则在赋值之前引用的局部变量'username'将出现错误。

@login_required
def createPatient(request):
    form=PatientForm(request.POST, request.FILES)
    # try:
    if request.method == "POST":
        if form.is_valid():
        
            first_name = form.cleaned_data['first_name']
            last_name = form.cleaned_data['last_name']
            username = form.cleaned_data['username']
            email = form.cleaned_data['email']
            password = form.cleaned_data['password']
            address = form.cleaned_data['address']
            phone_number = form.cleaned_data['phone_number']
            dob = form.cleaned_data['dob']
            gender = form.cleaned_data['gender']
        
    
            user = CustomUser.objects.create_user(username=username, email=email,password=password, first_name=first_name, last_name=last_name,user_type=5)
            user.patients.address = address
            user.patients.phone_number = phone_number
            user.patients.dob=dob
            user.patients.gender=gender
            user.save()
        else:
            # handle in case of form is not valid, i.e. form have some errors
    else:
        # handle in case of user send a GET request ( like raise error GET method not allowed)