ros2idl support

[MaxPRon]

Hello everyone,

I'm trying to read from a specific topic with wit ros2idl defined message. Here is a the slightly modified example:

`
def read_all_messages(filename,topics):

messages = []

with open(filename, "rb") as f:
    reader = make_reader(f)
    decoder = Decoder()

    for schema, channel, message in reader.iter_messages(topics=topics):
        messages.append(decoder.decode(schema, message))

return messages`

However I always get the following message error:

Exception has occurred: McapROS2DecodeError can't parse schema with encoding "ros2idl"

Is there something I'm missing or is this not yet supported ?

Best regards and thanks a lot already,

Max

[defunctzombie]

I don't recall that we've added support for ros2idl to the python ros2 mcap support package. If you have a ros2idl mcap file you created using ROS I'd recommend using the ROS python libraries to read it.

[MaxPRon]

Thanks for the answer. This means it's currently only possible with the respective ros2 installation meaning all message definitions installed etc. ?

[defunctzombie]

I believe that's the situation for reading ros2idl messages but could be wrong on that and there might be a way without a full install of all messages.

For anyone keen to explore adding support to read these without a full ROS2 install - the place to do that for mcap would be here: https://github.com/foxglove/mcap/tree/main/python/mcap-ros2-support

cc @emersonknapp

[MaxPRon]

@defunctzombie Thanks! There was an announcement recently regarding foxglove studio: https://foxglove.dev/blog/announcing-ros2-idl-support-in-foxglove-studio

It might hasn't made it to the helper functions yet. But I'll see what I can figure out