data = [
{'number':'BB22', 'am_sum':0},
{'number':'BB23', 'am_sum':None},
{'number':'BB24', 'am_sum':0}
]
for i in data:
for k, v in i.iteritems():
i[k] = 0 if v is None else v
print(data)
ZGF0YSA9IFsKCXsnbnVtYmVyJzonQkIyMicsICdhbV9zdW0nOjB9LAoJeydudW1iZXInOidCQjIzJywgJ2FtX3N1bSc6Tm9uZX0sCgl7J251bWJlcic6J0JCMjQnLCAnYW1fc3VtJzowfQpdCgpmb3IgaSBpbiBkYXRhOgogICAgZm9yIGssIHYgaW4gaS5pdGVyaXRlbXMoKToKICAgICAgICBpW2tdID0gMCBpZiB2IGlzIE5vbmUgZWxzZSB2CgpwcmludChkYXRhKQ==