Django表单无效

# 示例表单类
from django import forms

class ContactForm(forms.Form):
    name = forms.CharField(max_length=100)
    email = forms.EmailField()
    message = forms.CharField(widget=forms.Textarea)

# 视图处理表单提交
def contact_view(request):
    if request.method == 'POST':
        form = ContactForm(request.POST)
        if form.is_valid():
            # 处理有效数据
            pass
        else:
            # 输出错误信息
            print(form.errors)
    else:
        form = ContactForm()
    return render(request, 'contact.html', {'form': form})

class ContactForm(forms.Form):
    # ... 其他字段 ...

    def clean_email(self):
        email = self.cleaned_data['email']
        if not email.endswith('@example.com'):
            raise forms.ValidationError("Email 必须以 @example.com 结尾")
        return email

<!-- 在模板中 -->
<form method="post">
    {% csrf_token %}
    {{ form.as_p }}
    <button type="submit">Submit</button>
</form>

class MyModelForm(forms.ModelForm):
    class Meta:
        model = MyModel
        fields = '__all__'

    def clean(self):
        cleaned_data = super().clean()
        # 自定义逻辑处理数据库约束
        return cleaned_data