Django 表单验证消息未显示

我试图限制可以以表单上传的文件类型、大小和扩展名。该功能似乎有效，但未显示验证错误消息。我意识到if file._size > 4*1024*1024可能不是最好的方法 - 但我稍后会处理这个问题。

这是 forms.py：

class ProductForm(forms.ModelForm):
    class Meta:
        model = Product
        fields = ['name', 'description', 'url', 'product_type', 'price', 'image', 'image_url', 'product_file']
        labels = {
            'name': 'Product Name',
            'url': 'Product URL',
            'product_type': 'Product Type',
            'description': 'Product Description',
            'image': 'Product Image',
            'image_url': 'Product Image URL',
            'price': 'Product Price',
            'product_file': 'Product Zip File',
        }
        widgets = {
            'description': Textarea(attrs={'rows': 5}),
        }

    def clean(self):
        file = self.cleaned_data.get('product_file')

        if file:
            if file._size > 4*1024*1024:
                raise ValidationError("Zip file is too large ( > 4mb )")
            if not file.content-type in ["zip"]:
                raise ValidationError("Content-Type is not Zip")
            if not os.path.splitext(file.name)[1] in [".zip"]:
                raise ValidationError("Doesn't have proper extension")

                return file
            else:
                raise ValidationError("Couldn't read uploaded file")

...这是我用于该表单的视图：

def post_product(request):
    # if this is a POST request we need to process the form data
    if request.method == 'POST':
        # create a form instance and populate it with data from the request:
        form = ProductForm(data = request.POST, files = request.FILES)
        # check whether it's valid:
        if form.is_valid():
            # process the data in form.cleaned_data as required
            product = form.save(commit = False)
            product.user = request.user
            product.likes = 0
            product.save()
        # redirect to a new URL:
        return HttpResponseRedirect('/products')

我缺少什么？

在您看来，无论表单是否有效，您都在执行重定向 - 因此 Django 没有地方显示表单错误。

执行此操作的正常方法是在以下情况下重新呈现表单：is_valid() is False:

if form.is_valid():
    # process the data in form.cleaned_data as required
    product.save()
    # redirect to a new URL - only if form is valid!
    return HttpResponseRedirect('/products')
else:
    ctx = {"form": form} 
    # You may need other context here - use your get view as a template
    # The template should be the same one that you use to render the form
    # in the first place.
    return render(request, "form_template.html", ctx}

您可能需要考虑使用基于类的FormView https://docs.djangoproject.com/en/2.0/ref/class-based-views/generic-editing/#formview为此，它处理重新呈现有错误的表单的逻辑。这比编写两个单独的 get 和 post 视图来管理表单更简单、更容易。即使您不这样做，使用一个视图来处理表单的 GET 和 POST 也会更容易。