loginform.non_field_errors.as_text的用法

登录的视图函数

def user_login(request):
    '''
    用户登录
    :param request:
    :return:
    '''
    if request.method == 'POST':
        loginform = LoginForm(request.POST)
        if loginform.is_valid():
            cleaned_data = loginform.cleaned_data
            user = authenticate(username=cleaned_data['username'], password=cleaned_data['password'])
            if user:
                if user.is_active:
                    login(request,user)
                    print request.session
                    return redirect(reverse('index'))
                else:
                    pass
            else:
                pass

    else:
        loginform = LoginForm()


    context = {
        'loginform': loginform,
    }
    return render(request, 'account/login.html', context=context)

前端模版代码

<form class="login-form" action="{% url 'account:user_login' %}" method="post">
            {%csrf_token%}
            {{ loginform.non_field_errors.as_text }}
            <div class="input-group">
                {{ loginform.username }}
                <label for="id_username" class="input-label">
                    <span class="label-title">用户名</span>
                </label>
            </div>
            <div class="input-group">
                {{ loginform.password }}
                <label for="id_password" class="input-label">
                    <span class="label-title">密码</span>
                </label>
            </div>
            <input id="submit" type="submit"  class="login-button"  value="登录"/>
        </form>

form代码

class LoginForm(forms.Form):
    username = forms.CharField(label='用户名', min_length=2, max_length=20, required=True, widget=forms.widgets.Input(attrs={'class': 'input-field'}))
    password = forms.CharField(label='密码', min_length=5, max_length=20, required=True, widget=forms.widgets.PasswordInput(attrs={'class': 'input-field'}))

    def clean_password(self):
        pwd_len = 10  # 密码不能小于6个字符
        cleaned_data = self.cleaned_data['password']
        if  len(cleaned_data) <= pwd_len:
            raise forms.ValidationError('密码必须大于10个字符！')

        return cleaned_data

问题：输入密码小于10个字符的时候， {{ loginform.non_field_errors.as_text }}没有显示任何报错信息