[django]添加额外的 form 错误信息

通过两种方法给 Django 表单添加额外的错误信息。

第一种方法，使用 form 自定义校验（更详细的请查看 django 官方文档）：

定义 clean 方法：

class RegisterForm(forms.Form):
    # ...

    def clean(self):
        cleaned_data = super(RegisterForm, self).clean()
        email = cleaned_data.get('email', '')
        username = cleaned_data.get('username', '')

        re_username = r'^[a-zA-Z\d][-a-zA-Z\d]*$'

        if User.objects.filter(email=email).exists():
            msg = 'This email address already exists!'
            self._errors['email'] = self.error_class([msg])
            del cleaned_data['email']

        elif not re.match(re_username, username):
            msg = ('Username may only contain alphanumeric characters or'
                   'dashes and cannot begin with a dash')
            self._errors['username'] = self.error_class([msg])
            del cleaned_data['username']

        # ...

        return cleaned_data

定义 clean_ 方法：

class SendForm(forms.Form):
    # ...

    def clean_recipient(self):
        data = self.cleaned_data['recipient']
        if not User.objects.filter(username=data).exists():
            raise forms.ValidationError("This user doesn't exists!")

        return data


def send(request, template_name='message/send.html', extra_context=None):
    if request.method == 'POST':
        form = SendForm(request.POST)
        if form.is_valid():
            # ....
            recipient = form.cleaned_data['recipient']

            recipient = User.objects.get(username=recipient)
            # ...
            return HttpResponseRedirect(reverse_lazy('inbox'))
    else:
        form = SendForm()

    context = {
        'form': form,
    }
    if extra_context:
        context.update(extra_context)
    return render_to_response(template_name, context,
                              context_instance=RequestContext(request))

第二种方法，更新 form.errors 字典：

from django.forms.util import ErrorList


def send(request, template_name='message/send.html', extra_context=None):
    if request.method == 'POST':
        form = SendForm(request.POST)
        if form.is_valid():
            # ....
            recipient = form.cleaned_data['recipient']

            try:
                recipient = User.objects.get(username=recipient)
            except ObjectDoesNotExist:
                request.method = 'GET'
                error_msg = ["This user doesn't exists!"]
                form.errors['recipient'] = ErrorList(error_msg)
                extra_context = {'form': form}
                return send(request, template_name, extra_context)

            # ...
            return HttpResponseRedirect(reverse_lazy('inbox'))
    else:
        form = SendForm()

    context = {
        'form': form,
    }
    if extra_context:
        context.update(extra_context)
    return render_to_response(template_name, context,
                              context_instance=RequestContext(request))

参考

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