限制用户可以上传的文件数量

Question

我有一个多文件上传，并希望将用户限制为每个上传 3 次。我的问题是我需要知道user已经在数据库中创建了多少个文件以及他们当前正在上传多少个文件（他们可以一次上传多个文件，并且可以上传多次）。

我尝试了很多事情，包括：

创建验证器（验证器传递的是添加的实际文件，而不是model，因此我无法访问model以获取它的id调用if StudentUploadedFile.objects.filter(student_lesson_data=data.id).count() >= 4:）。

在clean(self):( 中clean进行验证一次只通过一个实例，并且在清除所有文件之前不会更新数据库，因此我可以计算数据库中已有的文件，但无法计算当前正在上传的文件数量)。

使用pre-save方法（如果在传递给我的pre-save方法的每个文件之间更新了数据库，它将起作用，但只有在上传的所有文件都通过我的pre-save方法后才更新数据库）。

我的post-save尝试：

@receiver(pre_save, sender=StudentUploadedFile)
def upload_file_pre_save(sender, instance, **kwargs):

    if StudentUploadedFile.objects.filter(student_lesson_data=instance.data.id).count() >= 4:
        raise ValidationError('Sorry, you cannot upload more than three files')

编辑：

模型.py

class StudentUploadedFile(models.Model):
    student_lesson_data = models.ForeignKey(StudentLessonData, related_name='student_uploaded_file', on_delete=models.CASCADE)
    student_file = models.FileField(upload_to='module_student_files/', default=None)

视图.py

class StudentUploadView(View):
    def get(self, request):
        files_list = StudentUploadedFile.objects.all()
        return render(self.request, 'users/modules.html', {'student_files': files_list})

    def post(self, request, *args, **kwargs):
        form = StudentUploadedFileForm(self.request.POST, self.request.FILES)
        form.instance.student_lesson_data_id = self.request.POST['student_lesson_data_id']

        if form.is_valid():
            uploaded_file = form.save()

            # pass uploaded_file data and username so new file can be added to students file list using ajax
            # lesson_id is used to output newly added file to corresponding newly_added_files div
            data = {'is_valid': True, 'username': request.user.username, 'file_id': uploaded_file.id, 'file_name': uploaded_file.filename(),
            'lesson_id': uploaded_file.student_lesson_data_id, 'file_path': str(uploaded_file.student_file)}
        else:
            data = {'is_valid': False}
        return JsonResponse(data)

模板文件

<form id='student_uploaded_file{{ item.instance.id }}'>
                                                {% csrf_token %}
                                                <a href="{% url 'download_student_uploaded_file' username=request.user.username file_path=item.instance.student_file %}" target='_blank'>{{ item.instance.filename }}</a>
                                                <a href="{% url 'delete_student_uploaded_file' username=request.user.username file_id=item.instance.id %}" class='delete' id='{{ item.instance.id }}'>Delete</a>
                                            </form>

js

$(function () {
    // open file explorer window
    $(".js-upload-photos").on('click', function(){
        // concatenates the id from the button pressed onto the end of fileupload class to call correct input element
        $("#fileupload" + this.id).click();
     });

    $('.fileupload_input').each(function() {
        $(this).fileupload({
            dataType: 'json',
            done: function(e, data) { // process response from server
            // add newly added files to students uploaded files list
            if (data.result.is_valid) {
                $("#newly_added_files" + data.result.lesson_id).prepend("<form id='student_uploaded_file" + data.result.file_id +
                "'><a href='/student_hub/" + data.result.username + "/download_student_uploaded_file/" +
                data.result.file_path + "' target='_blank'>" + data.result.file_name + "</a><a href='/student_hub/" + data.result.username +
                "/delete_student_uploaded_file/" + data.result.file_id + "/'  class='delete' id=" + data.result.file_id + ">Delete</a></form>")
            }
            }
        });
    });

更新：forms.py

class StudentUploadedFileForm(forms.ModelForm):
    student_file = forms.FileField(widget=forms.ClearableFileInput(attrs={'multiple': True}))

查看.py

class StudentUploadView(View):
    model = StudentUploadedFile
    max_files_per_lesson = 3

    def post(self, request, *args, **kwargs):
        lesson_data_id = request.POST['student_lesson_data_id']
        current_files_count = self.model.objects.filter(
            student_lesson_data_id=lesson_data_id
        ).count()
        avail = self.max_files_per_lesson - current_files_count
        file_list = request.FILES.getlist('student_file')
        print(len(file_list))
        if avail - len(file_list) < 0:
            return JsonResponse(data={
                'is_valid': False,
                'reason': f'Too many files: you can only upload {avail}.'
            })
        else:
            for f in file_list:
                print(f)
                
        data = {'test': True}
        return JsonResponse(data)

谢谢你。

Answer 1

所以它的要点是你正在使用 jQuery.each通过 AJAX 上传图像。对 Django 视图的每个 POST 请求都是单个文件上传，但可能同时有多个请求。

尝试这个：

形式.py：

class StudentUploadedFileForm(forms.ModelForm):

    class Meta:
        model = StudentUploadedFile
        fields = ('student_file', )

    def __init__(self, *args, **kwargs):
        """Accept a 'student_lesson_data' parameter."""
        self._student_lesson_data = kwargs.pop('student_lesson_data', None)
        super(StudentUploadedFileForm, self).__init__(*args, **kwargs)

    def clean(self):
        """
        Ensure that the total number of student_uploaded_file instances that
        are linked to the student_lesson_data parameter are within limits."""
        cleaned_data = super().clean()
        filecount = self._student_lesson_data.student_uploaded_file.count()
        if filecount >= 3:
            raise forms.ValidationError("Sorry, you cannot upload more than three files")
        return cleaned_data

视图.py:

class StudentUploadView(View):
    def get(self, request):
        # stuff ...

    def post(self, request, *args, **kwargs):
        sld_id = request.POST.get('student_lesson_data_id', None)
        student_lesson_data = StudentLessonData.objects.get(id=sld_id)
        form = StudentUploadedFileForm(
            request.POST,
            request.FILES,
            student_lesson_data=student_lesson_data
        )

        if form.is_valid():
            uploaded_file = form.save()
            # other stuff ...