如何将 Bytes 对象转换为 _io.BytesIO python？

Question

我正在制作一个简单的Flask API来上传图像并执行一些操作，然后将其作为二进制存储在数据库中，然后我想使用 send_file()函数下载它，但是，当我传递像字节这样的图像时，它会给我一个错误:

return send_file(BytesIO.read(image.data), attachment_filename='f.jpg', as_attachment=True) TypeError: descriptor

“read”需要“_io.BytesIO”对象，但收到“bytes”

我的上传图像的代码如下：

@app.route('/upload', methods=['POST'])
def upload():
    images = request.files.getlist('uploadImages')
    n = 0
    for image in images:
        fileName = image.filename.split('.')[0]
        fileFormat = image.filename.split('.')[1]
        imageRead = image.read()
        img = BytesIO(imageRead)
        with graph.as_default():
            caption = generate_caption_from_file(img)
        newImage = imageDescription(name=fileName, format=fileFormat, description=caption,
                                    data=imageRead)
        db.session.add(newImage)
        db.session.commit()
        n = n + 1
    return str(n) + ' Image has been saved successfully'

我的下载图像的代码：

@app.route('/download/<int:id>')
def download(id):
    image = imageDescription.query.get_or_404(id)
    return send_file(BytesIO.read(image.data), attachment_filename='f.jpg', as_attachment=True)

任何人都可以帮忙吗？？？

Answer 1

看来你很困惑io.BytesIO。让我们看一些使用的示例BytesIO。

>>> from io import BytesIO
>>> inp_b = BytesIO(b'Hello World', )
>>> inp_b
<_io.BytesIO object at 0x7ff2a71ecb30>
>>> inp.read() # read the bytes stream for first time
b'Hello World'
>>> inp.read() # now it is positioned at the end so doesn't give anything.
b''
>>> inp.seek(0) # position it back to begin
>>> BytesIO.read(inp) # This is same as above and prints bytes stream
b'Hello World'
>>> inp.seek(0)
>>> inp.read(4) # Just read upto four bytes of stream. 
>>> b'Hell'

read这应该能让您了解on 的工作原理BytesIO。我认为你需要做的是这个。

return send_file(
    BytesIO(image.data),
    mimetype='image/jpg',
    as_attachment=True,
    attachment_filename='f.jpg'
)