How web2py work with blob

[Константин Комков]

In my table I have Field('GRAPH'). In database (firebird 2.5) type if this field is BLOB. But if in tables.py I indicate that field as blob then web2py return error:

<class 'binascii.Error'> Invalid base64-encoded string: number of data characters (17) cannot be 1 more than a multiple of 4

Версия

web2py™	Version 2.18.5-stable+timestamp.2019.04.08.04.22.03
Python	Python 3.7.3: C:\Python\python.exe (prefix: C:\Python)

Error snapshot 

Error(Invalid base64-encoded string: number of data characters (17) cannot be 1 more than a multiple of 4)

Function argument list

(s=b'\x01\x00\x00\x00\x03\x00\x00\x00\x00\xc0W\xe5@...0\x00\x00`\x7f\xe5@\x00\x00\x00\x00\x00\x85\xe5@', altchars=None, validate=False)

Code listing

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        altchars = _bytes_from_decode_data(altchars)
        assert len(altchars) == 2, repr(altchars)
        s = s.translate(bytes.maketrans(altchars, b'+/'))
    if validate and not re.match(b'^[A-Za-z0-9+/]*={0,2}$', s):
        raise binascii.Error('Non-base64 digit found')
    return binascii.a2b_base64(s)


def standard_b64encode(s):
    """Encode bytes-like object s using the standard Base64 alphabet.

Variables

global binascii	<module 'binascii' (built-in)>
binascii.a2b_base64	<built-in function a2b_base64>
s	b'\x01\x00\x00\x00\x03\x00\x00\x00\x00\xc0W\xe5@...0\x00\x00`\x7f\xe5@\x00\x00\x00\x00\x00\x85\xe5@'

It's not problem because if I not indicate type for that field I can do my query. It's interesting why web2py reading base64 string, because blob is not always base64.