Django StreamingHttpResponse格式错误 [英] Django StreamingHttpResponse format error

问题描述

我有简单的Django视图，用于从Amazon s3下载文件。
在本地保存文件的测试是否正确：

I have simple Django view, for downloading file from Amazon s3. Test by saving file locally was alright:

def some_view(request):

    res = s3.get_object(...)

    try:
        s3_file_content = res['Body'].read()
        with open("/Users/yanik/ololo.jpg", 'wb') as f:
            f.write(s3_file_content)
            # file saved and I can view it
    except:
        pass

切换到 StreamingHttpResponse 我的文件格式不正确（无法打开）甚至错误的大小（如果原始的是317kb的图像输出木头在大约620kb）

When switch to StreamingHttpResponse I got incorrect file format (can't open) and even wrong size (If original is 317kb image the output wood be around 620kb)

def some_view(request):

    res = s3.get_object(...)

    response = StreamingHttpResponse(res['Body'].read(), content_type=res['ContentType'])
    response['Content-Disposition'] = 'attachment;filename=' + 'ololo.jpg'
    response['ContentLength'] = res['ContentLength']
    return response

尝试了许多不同的设置，但到目前为止没有什么对我有用。输出文件已损坏。

Tried many different setting, but so far nothing worked for me. The output file is broken.

我设法获得更多的首个信息。如果我将第一个样本中的文件写入方法从'wb'更改为'w'模式，我将具有相同的输出与 StreamingHttpResponse （第一个视图将生成相同的破碎文件）。
所以看起来我必须告诉http头，我的输出是在二进制格式

I managed to get more debuting information. If I change my file writing method in first sample from 'wb' to 'w' mode I'll have same output as with StreamingHttpResponse (first view will generate same broken file). So it looks like I must tell http header that my output is on binary format

现在我明白了问题。 但仍然没有解决方案。
res ['Body']。read（）返回字节类型和 StreamingHttpResponse 遍历这些字节，返回字节码。所以我漂亮的输入字节'... \x05cgr\xb8 =：\xd0\xc3\x97U\xf4\xf3\xdc\xf0 * \xd4 @ \\ \\ xff\xd9'强制转换为数组，如： [...，195，151，85，244，243，220，240，42，212， 255，217] ，然后像串联字符串一样下载。截图： http://take.ms/JQztk
如你所见，最后的列表元素。

Now I'm understand the problem. But still don't have the solution. The res['Body'].read() returns bytes type and StreamingHttpResponse iterate through these bytes, which returns byte codes. So my pretty incoming bytes '...\x05cgr\xb8=:\xd0\xc3\x97U\xf4\xf3\xdc\xf0*\xd4@\xff\xd9' force converted to array like: [ ... , 195, 151, 85, 244, 243, 220, 240, 42, 212, 64, 255, 217] and then downloaded like concatenated strings. Screenshot: http://take.ms/JQztk As you see, the list elements in the end.

StreamingHttpResponse.make_bytes
"""Turn a value into a bytestring encoded in the output charset."""

推荐答案

https://docs.djangoproject.com/en/1.9/ref/request-response/#streaminghttpresponse-objects

StreamingHttpResponse需要一个迭代器。我想如果你的文件是二进制（image），那么StreamingHttpResponse不是最好的解决方案，或者你应该创建这个文件的块。

StreamingHttpResponse needs an iterator. I think if your file is binary (image), then StreamingHttpResponse is not the best solution, or you should create chunks of that file.

Bytearray是一个迭代器，但也许你想要去不是字节/字符的行。

Bytearray is an iterator but perhaps you want to go on lines not on bytes/characters.

我不知道你的文件是否是基于行的文本数据，但如果是，你可以创建一个生成器为了迭代文件像对象：

I'm not sure if your file is line based text data, but if it is, you could create a generator in order to iterate over the file like object:

def line_generator(file_like_obj):
    for line in file_like_obj:
        yield line

，并将该生成器提供给StreamingHttpResponse：

and feed that generator to the StreamingHttpResponse:

some_view(request):
    res = s3.get_object(...)
    response = StreamingHttpResponse(line_generator(res['Body']), ...)
    return response

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