如何使用django rest framework的测试客户端测试二进制文件上传？

Question

我有一个Django应用程序，其视图接受要上传的文件。使用Django REST框架，我对APIView进行子类化并实现post（）方法，如下所示：

class FileUpload(APIView):
    permission_classes = (IsAuthenticated,)

    def post(self, request, *args, **kwargs):
        try:
            image = request.FILES['image']
            # Image processing here.
            return Response(status=status.HTTP_201_CREATED)
        except KeyError:
            return Response(status=status.HTTP_400_BAD_REQUEST, data={'detail' : 'Expected image.'})

现在，我正在尝试编写几个单元测试，以确保需要身份验证，并实际处理上传的文件。

class TestFileUpload(APITestCase):
    def test_that_authentication_is_required(self):
        self.assertEqual(self.client.post('my_url').status_code, status.HTTP_401_UNAUTHORIZED)

    def test_file_is_accepted(self):
        self.client.force_authenticate(self.user)
        image = Image.new('RGB', (100, 100))
        tmp_file = tempfile.NamedTemporaryFile(suffix='.jpg')
        image.save(tmp_file)
        with open(tmp_file.name, 'rb') as data:
            response = self.client.post('my_url', {'image': data}, format='multipart')
            self.assertEqual(status.HTTP_201_CREATED, response.status_code)

但是当REST框架试图编码请求时，这将失败

Traceback (most recent call last):
  File "/home/vagrant/.virtualenvs/myapp/lib/python3.3/site-packages/django/utils/encoding.py", line 104, in force_text
    s = six.text_type(s, encoding, errors)
UnicodeDecodeError: 'utf-8' codec can't decode byte 0xff in position 118: invalid start byte

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
  File "/home/vagrant/webapp/myproject/myapp/tests.py", line 31, in test_that_jpeg_image_is_accepted
    response = self.client.post('my_url', { 'image': data}, format='multipart')
  File "/home/vagrant/.virtualenvs/myapp/lib/python3.3/site-    packages/rest_framework/test.py", line 76, in post
    return self.generic('POST', path, data, content_type, **extra)
  File "/home/vagrant/.virtualenvs/myapp/lib/python3.3/site-packages/rest_framework/compat.py", line 470, in generic
    data = force_bytes_or_smart_bytes(data, settings.DEFAULT_CHARSET)
  File "/home/vagrant/.virtualenvs/myapp/lib/python3.3/site-packages/django/utils/encoding.py", line 73, in smart_text
    return force_text(s, encoding, strings_only, errors)
  File "/home/vagrant/.virtualenvs/myapp/lib/python3.3/site-packages/django/utils/encoding.py", line 116, in force_text
    raise DjangoUnicodeDecodeError(s, *e.args)
django.utils.encoding.DjangoUnicodeDecodeError: 'utf-8' codec can't decode byte 0xff in position 118: invalid start byte. You passed in b'--BoUnDaRyStRiNg\r\nContent-Disposition: form-data; name="image"; filename="tmpyz2wac.jpg"\r\nContent-Type: image/jpeg\r\n\r\n\xff\xd8\xff[binary data omitted]' (<class 'bytes'>)

如何让测试客户端发送数据而不尝试将其解码为UTF-8？

Answer 1

您可以使用Django内置的SimpleUploadedFile：

from django.core.files.uploadedfile import SimpleUploadedFile

class TestFileUpload(APITestCase):
...

    def test_file_is_accepted(self):
        ...

       tmp_file = SimpleUploadedFile(
                      "file.jpg", "file_content", content_type="image/jpg")

       response = self.client.post(
                      'my_url', {'image': tmp_file}, format='multipart')
       self.assertEqual(response.status_code, status.HTTP_201_CREATED)

Answer 2

Python3用户：确保以mode='rb'（读取，二进制）打开文件。否则，当Django调用文件上的read时，utf-8编解码器将立即开始阻塞。文件应解码为二进制，而不是utf-8、ascii或任何其他编码。

# This won't work in Python 3
with open(tmp_file.name) as fp:
        response = self.client.post('my_url', 
                                   {'image': fp}, 
                                   format='multipart')

# Set the mode to binary and read so it can be decoded as binary
with open(tmp_file.name, 'rb') as fp:
        response = self.client.post('my_url', 
                                   {'image': fp}, 
                                   format='multipart')

Answer 3

在测试文件上载时，应该将流对象传递到请求中，而不是数据中。

@arocks在评论中指出了这一点

改为传递{'Image'： file}

但这并不能完全解释为什么需要它（也不符合问题）。对于这个特定的问题，你应该做

from PIL import Image

class TestFileUpload(APITestCase):

    def test_file_is_accepted(self):
        self.client.force_authenticate(self.user)

        image = Image.new('RGB', (100, 100))

        tmp_file = tempfile.NamedTemporaryFile(suffix='.jpg')
        image.save(tmp_file)
        tmp_file.seek(0)

        response = self.client.post('my_url', {'image': tmp_file}, format='multipart')

       self.assertEqual(status.HTTP_201_CREATED, response.status_code)

这将匹配一个标准的Django请求，其中文件作为流对象传入，Django REST框架处理它。当您只是传入文件数据时，Django和Django REST框架会将其解释为字符串，这会导致问题，因为它期待一个流。

对于那些来这里寻找另一个常见错误的人来说，为什么文件上传不起作用，但正常的表单数据会起作用：在创建请求时，请确保设置form="Multipart"。

这也带来了类似的问题，@RobinElvin在评论中指出了这一点

这是因为我错过了格式='多部分'