EncodeError: signal required for encoding when passing a partial dictionnary to Message.encode()

[Becheler]

Hello!

Great work with this library!

I have a simple question. I would expect to be able to write the following:

example_message = db.get_message_by_name('ExampleMessage')
data = example_message.encode( {'Temperature': 250.1} ) # note the missing keys here
message = can.Message(arbitration_id=example_message.frame_id, data=data)
can_bus.send(message)

This would be handy to shorten notation by defaulting values and manipulate variables as in data = message.encode( {key:val} )

However, it seems one has to specify the entire dictionary:

data = example_message.encode({'Temperature': 250.1, 'AverageRadius': 3.2, 'Enable': 1})

or else we get a cantools.database.errors.EncodeError: The signal "AverageRadius" is required for encoding.

Is there a way to bypass such limitation without having to build an entire dictionnary with defaulted values ?

Best wishes,

[zariiii9003]

Set strict=False. See docs

[Becheler]

Thanks for your answer,
However it seems it does not entirely solve my problem:

File "mymainl.py", line 73, in __myfunc
    data = message.encode( { key : val }, strict=False )
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "C:\Users\...\cantools\database\can\message.py", line 950, in encode
    encoded, padding_mask, all_signals = self._encode(self._codecs,
                                         ^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "C:\Users\...\cantools\database\can\message.py", line 786, in _encode
    encoded = encode_data(data,
              ^^^^^^^^^^^^^^^^^
  File "C:\Users\...\cantools\database\utils.py", line 112, in encode_data
    raw_signal_values = _encode_signal_values(signals, signal_values, scaling)
                        ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "C:\Users\...\cantools\database\utils.py", line 82, in _encode_signal_values
    value = signal_values[name]
  KeyError: 'OneOfMyKeys'

My guess is that the values have not been initialized by default (how to do so?) and so the signal_values does not contain the key name 🤔

[andlaus]

cantools does not provide default values for signals. The closest thing it has are the initial values, but they are conceptually slightly different (If I understood this correctly). If you want to use these as default values, you can do so using

db_msg = db.get_message_by_name("MyMessage")

msg_data = {}
for signal in db_msg.signals:
  if signal.initial is not None:
    msg_data[signal.name] = signal.initial

# set the values which you actually want to send

raw_data = db.encode_message(db_msg.name, msg_data)