rosapi tries to parse `IDL` files as `msg` files and errors

[russkel]

Description

If there is no msg files get_interface_path will return an idl path. This is then fed into the parse_message_string function for msg files. This ends up with a lot of errors spamming in the log.

https://github.com/RobotWebTools/rosbridge_suite/blob/ros2/rosapi/src/rosapi/stringify_field_types.py#L20

https://github.com/RobotWebTools/rosbridge_suite/blob/ros2/rosapi/src/rosapi/stringify_field_types.py#L24

• Library Version: main
• ROS Version: Iron release
• Platform / OS: Linux

Steps To Reproduce

Expected Behavior

Either parses IDL using the rosidl parser or errors once it detects the IDL extension and doesn't try to load it again.

Actual Behavior

[rosapi_node-19] Error processing '// generated from nmea0183_adapter/resource/msg_definition.idl.em' of 'nmea0183_msgs/UtcDateTime': '//'

[charlielito]

I think this happens for custom-built messages. I managed to implement a workaround to be able to parse them:

def extract_msg_path_from_idl(idl_path):
    with open(idl_path, 'r', encoding='utf-8') as idl_file:
        idl_content = idl_file.read()
    
    # Try to extract the original .msg file path from content. Usually in the first lines
    # there is a part that says "// with input from <path>" and path is related to the original .msg file
    msg_file_info = [line for line in idl_content.split('\n') if '// with input from' in line]
    if msg_file_info:
        msg_path = msg_file_info[0].split('// with input from')[-1].strip()
        # Remove "msg/" from the path, since the actual path doesn't have it
        msg_path = msg_path.replace('msg/', '')
        # Find parent directory of the idl just before the share folder
        share_dir = idl_path.split('share')[0]
        # Construct the full path to the .msg file
        return os.path.join(share_dir, 'share', msg_path)
    
    return idl_path

def stringify_field_types(root_type):
    definition = ""
    seen_types = set()
    deps = [root_type]
    is_root = True
    while deps:
        ty = deps.pop()
        parts = ty.split("/")
        if not is_root:
            definition += "\n================================================================================\n"
            definition += f"MSG: {ty}\n"
        is_root = False

        msg_name = parts[2] if len(parts) == 3 else parts[1]
        interface_name = ty if len(parts) == 3 else f"{parts[0]}/msg/{parts[1]}"

        # Try to get the .msg file first
        msg_path = get_interface_path(interface_name)

        # If custom we get instead the .idl implementation
        if msg_path.endswith('.idl'):
            msg_path = extract_msg_path_from_idl(msg_path)

        with open(msg_path, encoding="utf-8") as msg_file:
            msg_definition = msg_file.read()
        definition += msg_definition

        spec = parse_message_string(parts[0], msg_name, msg_definition)
        for field in spec.fields:
            is_builtin = field.type.pkg_name is None
            if not is_builtin:
                field_ty = f"{field.type.pkg_name}/{field.type.type}"
                if field_ty not in seen_types:
                    deps.append(field_ty)
                    seen_types.add(field_ty)

    return definition

Hope it helps

[russkel]

I have a PR on rosidl_parser which adds a parser for IDL files, but as per tradition it just sits there unreviewed.

Thanks for your patch, but we stopped using rosbridge and changed to foxbridge due to performance increases.

[charlielito]

@russkel can you point me to the PR url? Thanks!

[russkel]

https://github.com/ros2/rosidl/pull/697

@russkel can you point me to the PR url? Thanks!