Exception when trying to decode multipart payloads about pyais HOT 2 CLOSED

The error message that you get is misleading. Trying to decode a multipart message without its predecessor will yield this error, because the payload can not be decoded properly.

In the documentation I point out that decode_msg is only a convenience function for quick experimenting/testing. It is designed to decode a single message. However, it can be used to decode multipart messages, if you provide all parts:

decode_msg(
    "!AIVDM,2,1,0,A,539p4OT00000@7W3K@08ThiLE8@E:0000000001S0h9135Pl?0R0C@UDQp00,0*68",
    "!AIVDM,2,2,0,A,00000000000,2*24"
)

Depending on your use case, there are more stable methods to decode messages. Some examples:

1. Decoding messages from a file

from pyais.stream import FileReaderStream

for msg in FileReaderStream("sample.ais"):
    decoded_message = msg.decode()

2. Reading from a socket

from pyais.stream import TCPStream

url = 'ais.exploratorium.edu'
port = 80

for msg in TCPStream(url, port=80):
    decoded_message = msg.decode()
    ais_content = decoded_message.content
    print(ais_content)
    # Do something with the ais message

In both cases, the library will handle multipart messages for you. It will also handle out of order message decoding, which can happen when receiving messages via UDP.

from pyais.

I added more useful error messages: #38

from pyais.