django，“some_field”属性没有与之关联的文件答案

【问题标题】：django, 'some_field' attribute has no file associated with itdjango，“some_field”属性没有与之关联的文件
【发布时间】：2018-06-26 18:14:03
【问题描述】：

views.py

if request.is_ajax():
    testpic = TestPic.objects.get(pk=1)

    form = TestPicForm(request.POST, request.FILES, instance=testpic)
    if form.is_valid():
        form.save()

forms.py

class TestPicForm(forms.ModelForm):

    class Meta:
        from .models import TestPic
        model = TestPic
        fields = ('file', 'file_50',)

    def save(self):
        test_photo = super(TestPicForm, self).save()
        file = user_photo.file
        image = Image.open(file)
        rotated_image = image.rotate(90, expand=True)
        cropped_image = rotated_image.resize((300, 300), Image.ANTIALIAS)
        cropped_50_image = rotated_image.resize((50, 50), Image.ANTIALIAS)

        cropped_image.save(test_photo.file.path)
        file.seek(0)  
        cropped_50_image.save(test_photo.file_50.path)

        return user_photo

models.py

class TestPic(models.Model):
    file = models.ImageField(null=True, blank=True, default=None, upload_to="photo/%Y/%m/%d")
    file_50 = models.ImageField(null=True, blank=True, default=None, upload_to="photo/%Y/%m/%d")

此代码用于上传图像文件，将其大小调整两个不同的大小并保存。

遗憾的是，它仅在字段 file_50 上有任何文件时才有效。

file

some_file_50.jpeg

当file_50 字段上没有文件时，它会抛出错误： The 'file_50' attribute has no file associated with it.

问题：我该如何解决？感谢阅读。

添加回溯：

Internal Server Error: /accounts/crop/
Traceback (most recent call last):
  File "D:\pythonDev\interpreters\forMultichat\lib\site-packages\django\core\handlers\exception.py", line 35, in inner
    response = get_response(request)
  File "D:\pythonDev\interpreters\forMultichat\lib\site-packages\django\core\handlers\base.py", line 128, in _get_response
    response = self.process_exception_by_middleware(e, request)
  File "D:\pythonDev\interpreters\forMultichat\lib\site-packages\django\core\handlers\base.py", line 126, in _get_response
    response = wrapped_callback(request, *callback_args, **callback_kwargs)
  File "D:\pythonDev\project\upward\chatkaboo\authapp\views.py", line 833, in crop
    form.save()
  File "D:\pythonDev\project\upward\chatkaboo\authapp\forms.py", line 182, in save
    cropped_50_image.save(user_photo.file_50.path)
  File "D:\pythonDev\interpreters\forMultichat\lib\site-packages\django\db\models\fields\files.py", line 56, in path
    self._require_file()
  File "D:\pythonDev\interpreters\forMultichat\lib\site-packages\django\db\models\fields\files.py", line 38, in _require_file
    raise ValueError("The '%s' attribute has no file associated with it." % self.field.name)
ValueError: The 'file_50' attribute has no file associated with it.

添加html、jquery ajax上传代码：

  <form method="post" enctype="multipart/form-data" id="formUpload">
      <input type="file" name="file" required id="id_file">
  </form>
<script>
      $(".js-crop-and-upload").click(function () {
        var form_upload = $("#formUpload")[0];
        var form_data = new FormData(form_upload);

        form_data.append('some', "some_val");
        $.ajax({
            url:'/accounts/crop/',
            type:'post',
            dataType:'json',
            cache:false,
            processData: false,
            contentType: false,
            data:form_data,
            success:function (data) {
                console.log(data)
            }
     });
</script>

【问题讨论】：

你能添加完整的回溯吗？通常在这种情况下，这意味着某些东西（例如模板）正在尝试专门引用该字段。
@MrName 谢谢，我添加了回溯。请再检查一遍好吗？
我添加了html和脚本代码。

标签： python django

【解决方案1】：

查看您的save 方法，我看不到您将修改后的文件分配给模型的file_50 字段的位置。我假设您想要做的更像是以下内容？

cropped_50_image = rotated_image.resize((50, 50), Image.ANTIALIAS) 
# Assign cropped image to image_50 model field
user_photo.image_50 = cropped_50_image
user_photo.save()

这只是伪代码。在分配文件之前，您可能需要包装文件以使其成为正确的 Django 文件，as discussed here。

【讨论】：