How to convert Bytes object to _io.BytesIO python?

Question

I am making a simple flask API for uploading an image and do some progresses then store it in the data base as binary, then i want to download it by using send_file() function but, when i am passing an image like a bytes it gives me an error:

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

'read' requires a '_io.BytesIO' object but received a 'bytes'

and My code for upload an image as follow:

@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'

And my code for downloading an image:

@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)

any one can help please???

Answer 1

It seems you are confused io.BytesIO. Let's look at some examples of using 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'

This should give you an idea of how read on BytesIO works. I think what you need to do is this.

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