Django StreamingHttpResponse格式错误

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：
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/JQztkAs 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

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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