我正在学习如何在 Django 中上传文件，在这里我遇到了一个应该是微不足道的问题，错误:

The submitted data was not a file. Check the encoding type on the form.

以下是详细信息。

注意:我也看过 Django Rest Framework ImageField ，我试过了

serializer = ImageSerializer(data=request.data, files=request.FILES)

但我明白了

TypeError: __init__() got an unexpected keyword argument 'files'

我有一个 Image 模型，我想通过 Django REST 框架与之交互:

models.py

class Image(models.Model):
    image = models.ImageField(upload_to='item_images')
    owner = models.ForeignKey(
        User, related_name='uploaded_item_images',
        blank=False,
    )
    time_created = models.DateTimeField(auto_now_add=True)

serializers.py

class ImageSerializer(serializers.ModelSerializer):
    image = serializers.ImageField(
        max_length=None, use_url=True,
    )

    class Meta:
        model = Image
        fields = ("id", 'image', 'owner', 'time_created', )

settings.py

'DEFAULT_PARSER_CLASSES': (
    'rest_framework.parsers.JSONParser',
    'rest_framework.parsers.FormParser',
    'rest_framework.parsers.MultiPartParser',
),

前端(使用AngularJS和angular-restmod或$resource)用owner发送JSON数据和 image 的形式:

输入:

{"owner": 5, "image": "data:image/jpeg;base64,/9j/4QqdRXhpZgAATU0A..."}

在后端，request.data显示

{u'owner': 5, u'image': u'data:image/jpeg;base64,/9j/4QqdRXhpZgAATU0AKgAAA..."}

但随后 ImageSerializer(data=request.data).errors 显示错误

ReturnDict([('image', [u'The submitted data was not a file. Check the encoding type on the form.'])])

我想知道我应该怎么做才能修复这个错误？

编辑:JS 部分

相关的前端代码由两部分组成:一个angular-file-dnd directive(可用here)文件到页面和 angular-restmod，它提供了 CRUD 操作:

<!-- The template: according to angular-file-dnd, -->
<!-- it will store the dropped image into variable $scope.image -->
<div file-dropzone="[image/png, image/jpeg, image/gif]" file="image" class='method' data-max-file-size="3" file-name="imageFileName">
  <div layout='row' layout-align='center'>
    <i class="fa fa-upload" style='font-size:50px;'></i>
  </div>
  <div class='text-large'>Drap & drop your photo here</div>
</div>



# A simple `Image` `model` to perform `POST`
$scope.image_resource = Image.$build();

$scope.upload = function() {
  console.log("uploading");
  $scope.image_resource.image = $scope.image;
  $scope.image_resource.owner = Auth.get_profile().user_id;
  return $scope.image_resource.$save();
};

关于这个问题的更新:现在我切换到使用 ng-file-upload，它以正确的格式发送图像数据。

最佳答案

您遇到的问题是 Django REST 框架 expects files to be uploaded as multipart form data ，通过标准的文件上传方式。这是typically a file field ，但 JavaScript Blob object also works用于 AJAX。

您希望使用 base64 编码字符串而不是原始文件上传文件，is not supported by default .有 Base64ImageField out there 的实现，但最有希望的一个came by a pull request .

由于这些主要是为 Django REST framework 2.x 设计的，我已经改进了拉取请求中的一个，并创建了一个应该与 DRF 3 兼容的。

serializers.py

from rest_framework import serializers    

class Base64ImageField(serializers.ImageField):
    """
    A Django REST framework field for handling image-uploads through raw post data.
    It uses base64 for encoding and decoding the contents of the file.

    Heavily based on
    https://github.com/tomchristie/django-rest-framework/pull/1268

    Updated for Django REST framework 3.
    """

    def to_internal_value(self, data):
        from django.core.files.base import ContentFile
        import base64
        import six
        import uuid

        # Check if this is a base64 string
        if isinstance(data, six.string_types):
            # Check if the base64 string is in the "data:" format
            if 'data:' in data and ';base64,' in data:
                # Break out the header from the base64 content
                header, data = data.split(';base64,')

            # Try to decode the file. Return validation error if it fails.
            try:
                decoded_file = base64.b64decode(data)
            except TypeError:
                self.fail('invalid_image')

            # Generate file name:
            file_name = str(uuid.uuid4())[:12] # 12 characters are more than enough.
            # Get the file name extension:
            file_extension = self.get_file_extension(file_name, decoded_file)

            complete_file_name = "%s.%s" % (file_name, file_extension, )

            data = ContentFile(decoded_file, name=complete_file_name)

        return super(Base64ImageField, self).to_internal_value(data)

    def get_file_extension(self, file_name, decoded_file):
        import imghdr

        extension = imghdr.what(file_name, decoded_file)
        extension = "jpg" if extension == "jpeg" else extension

        return extension

这应该用于替换 Django REST 框架提供的标准 ImageField。所以你的序列化器会变成

class ImageSerializer(serializers.ModelSerializer):
    image = Base64ImageField(
        max_length=None, use_url=True,
    )

    class Meta:
        model = Image
        fields = ("id", 'image', 'owner', 'time_created', )

这应该允许您指定 base64 编码的字符串，或 Django REST 框架通常期望的标准 Blob 对象。

关于python - Django REST Framework 上传图片 : "The submitted data was not a file"，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/28036404/