Convert from '_io.BytesIO' to a bytes-like object in python3.6?

Question

I am using this function to uncompress the body or a HTTP response if it is compressed with gzip, compress or deflate.

def uncompress_body(self, compression_type, body):
    if compression_type == 'gzip' or compression_type == 'compress':
        return zlib.decompress(body)
    elif compression_type == 'deflate':
        compressor = zlib.compressobj(9, zlib.DEFLATED, -zlib.MAX_WBITS)
        compressed = compressor.compress(body)
        compressed += compressor.flush()
        return base64.b64encode(compressed)

    return body

However python throws this error message.

TypeError: a bytes-like object is required, not '_io.BytesIO'

on this line:

return zlib.decompress(body)

Essentially, how do I convert from ‘_io.BytesIO’ to a bytes-like object?

Asked By: Dan

||

Source

Answer 1

It’s a file-like object. Read them:

>>> b = io.BytesIO(b'hello')
>>> b.read()
b'hello'

If the data coming in from body is too large to read into memory, you’ll want to refactor your code and use zlib.decompressobj instead of zlib.decompress.

Answered By: wim

Answer 2

In case you write into the object first, make sure to reset the stream before reading:

>>> b = io.BytesIO()
>>> image = PIL.Image.open(path_to_image)
>>> image.save(b, format='PNG')
>>> b.seek(0)
>>> b.read()
b'x89PNGrnx1anx00x00x00rIHDRx00x00x06xcfx00x00x03Wx08x02x00'

or directly get the data with getvalue

>>> b.getvalue()
b'x89PNGrnx1anx00x00x00rIHDRx00x00x06xcfx00x00x03Wx08x02x00'

Answered By: Alexander Pacha

Answer 3

b = io.BytesIO()
image = PIL.Image.open(path_to_image) # ie 'image.png'
image.save(b, format='PNG')
b.getbuffer().tobytes() # b'x89PNGrnx1anx00 ...

Answered By: Nwawel A Iroume

Convert from '_io.BytesIO' to a bytes-like object in python3.6?

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