Django表单文件字段在表单错误时消失

Here is the problem, I have a Django Form containing a File field, namely:

这是问题，我有一个包含File字段的Django表单，即：

photo = forms.FileField(help_text="Please attach a photo", required=False)

If the form validates, the File field is bounded and saved correctly. The problem is when the user fills all the form and it doesn't validate: the path of the selected file disappear.

如果表单有效，则“文件”字段将被绑定并正确保存。问题是当用户填写所有表单并且它不验证时：所选文件的路径消失。

So, if the user doesn't realize about this, he/she fix the other fields errors and submit again - with no photo this time.

因此，如果用户没有意识到这一点，他/她会修复其他字段错误并再次提交 - 这次没有照片。

Just in case, the form is created in the view like this:

以防万一，表单在视图中创建如下：

ProfileForm(request.POST or None, request.FILES or None)

and the HTML is:

而HTML是：

<div id="uniform-id_photo" class="uploader">
  <input id="id_photo" class="clearablefileinput" type="file" name="photo" size="19" style="opacity: 0;">
  <span class="filename" style="-moz-user-select: none;">No file selected</span>
  <span class="action" style="-moz-user-select: none;">Choose File</span>
</div>

Has anyone had the same problem before? Any thoughts towards a solution? :)

以前有没有人遇到过同样的问题？对解决方案的任何想法？ :)

Thanks!

谢谢！

2 个解决方案

#1

Unfortunately, this is a problem (really a security feature) imposed by browsers, and is not solvable, as such. Browsers will not let you specify an initial value for file inputs, and there's nothing that you will be able to do to work around that.

不幸的是，这是浏览器强加的一个问题（实际上是一种安全功能），并且不可解决。浏览器不允许您指定文件输入的初始值，并且您无法通过它来解决这个问题。

The reason is that if a website could do this, it would open up a vector that would allow any website to steal any file on your computer by guessing file paths--they could just have a script running in the background that tried to post interesting files back to the server.

原因是，如果一个网站可以做到这一点，它将打开一个矢量，允许任何网站通过猜测文件路径窃取您的计算机上的任何文件 - 他们可能只有一个脚本在后台运行，试图发布有趣的文件回到服务器。

The only workaround is to actually save the uploaded file on the server regardless of whether the form validates, and then when you render the form and errors back to the user, indicate that you have received a file and that they should only fill out that field to replace it.

唯一的解决方法是实际将上传的文件保存在服务器上，无论表单是否验证，然后当您将表单和错误呈现给用户时，表明您已收到文件并且他们应该只填写该字段替换它。

#2

I write some solution:

我写了一些解决方案：

class CustomClearableFileInput(ClearableFileInput):

def render(self, name, value, attrs=None):
    if len(<YourModel>.objects.filter(id=self.form_instance_id))>0:
        file = <YourModel>.objects.get(id=self.form_instance_id).<yourField>
    else:
        file = ''
    substitutions = {
        'initial_text': self.initial_text,
        'input_text': self.input_text,
        'clear_template': '',
        'clear_checkbox_label': self.clear_checkbox_label,
    }
    template = '%(input)s'
    substitutions['input'] = super(ClearableFileInput, self).render(name, value, attrs)
    self.template_with_initial = ('<p class="file-upload">%s</p>'
                        % self.template_with_initial)
    self.template_with_clear = ('<span class="clearable-file-input">%s</span>'
                       % self.template_with_clear)

    if value and hasattr(value, "url"):
        template = self.template_with_initial
        substitutions['initial'] = format_html(self.url_markup_template,
                                               value.url,
                                               force_text(value))
        if not self.is_required:
            checkbox_name = self.clear_checkbox_name(name)
            checkbox_id = self.clear_checkbox_id(checkbox_name)
            substitutions['clear_checkbox_name'] = conditional_escape(checkbox_name)
            substitutions['clear_checkbox_id'] = conditional_escape(checkbox_id)
            substitutions['clear'] = CheckboxInput().render(checkbox_name, False, attrs={'id': checkbox_id})
            substitutions['clear_template'] = self.template_with_clear % substitutions
            url = '' if file == '' else file.url
    else:
        template = self.template_with_initial

        substitutions['initial'] = format_html(self.url_markup_template,
                                               url,
                                               force_text(file))
        if not self.is_required:
            checkbox_name = self.clear_checkbox_name(name)
            checkbox_id = self.clear_checkbox_id(checkbox_name)
            substitutions['clear_checkbox_name'] = conditional_escape(checkbox_name)
            substitutions['clear_checkbox_id'] = conditional_escape(checkbox_id)
            if fav == '':
                substitutions['clear'] = CheckboxInput().render(checkbox_name, False, attrs={'id': checkbox_id, 'disabled': 'disabled'})
            else:
                substitutions['clear'] = CheckboxInput().render(checkbox_name, False, attrs={'id': checkbox_id})
            substitutions['clear_template'] = self.template_with_clear % substitutions



    return mark_safe(template % substitutions)

And then in your form you must write:

然后在你的表格中你必须写：

class <YourModel>Form(ModelForm):
    class Meta:
        model = <YourModel>
        fields = '__all__'
        widgets= {'<YourField>': CustomClearableFileInput}

    def __init__(self, *args, **kwargs):
        super(OperatorSettingsForm, self).__init__(*args, **kwargs)
        self.fields['<YourField>'].widget.form_instance_id = self.instance.id

It works for me. I think you will have no problem too :)

这个对我有用。我想你也没问题:)

#1

#2