Message._fill_message_args() fails on messages with fields of type 'time[]'

[astaa-nrec]

(on genpy version 0.4.10, ros_comm version 1.9.44)

To reproduce: define a message "rosbugs/msg/TimeArray.msg" with a single field:

time[] stamps

Build it and then try:

rostopic pub /test ros_bugs/TimeArray "{stamps: []}"

This fails with the error:

Traceback (most recent call last):
  File "/opt/ros/groovy/bin/rostopic", line 35, in <module>
    rostopic.rostopicmain()
  File "/opt/ros/groovy/lib/python2.7/dist-packages/rostopic/__init__.py", line 1654, in rostopicmain
    _rostopic_cmd_pub(argv)
  File "/opt/ros/groovy/lib/python2.7/dist-packages/rostopic/__init__.py", line 1330, in _rostopic_cmd_pub
    argv_publish(pub, msg_class, pub_args, rate, options.once, options.verbose)
  File "/opt/ros/groovy/lib/python2.7/dist-packages/rostopic/__init__.py", line 1354, in argv_publish
    publish_message(pub, msg_class, pub_args, rate, once, verbose=verbose)
  File "/opt/ros/groovy/lib/python2.7/dist-packages/rostopic/__init__.py", line 1224, in publish_message
    genpy.message.fill_message_args(msg, pub_args, keys=keys)
  File "/opt/ros/groovy/lib/python2.7/dist-packages/genpy/message.py", line 513, in fill_message_args
    _fill_message_args(msg, msg_args[0], keys, '')
  File "/opt/ros/groovy/lib/python2.7/dist-packages/genpy/message.py", line 461, in _fill_message_args
    _fill_val(msg, f, v, keys, prefix)
  File "/opt/ros/groovy/lib/python2.7/dist-packages/genpy/message.py", line 425, in _fill_val
    list_msg_class = get_message_class(base_type)
  File "/opt/ros/groovy/lib/python2.7/dist-packages/genpy/message.py", line 570, in get_message_class
    cls = _get_message_or_service_class('msg', message_type, reload_on_error=reload_on_error)
  File "/opt/ros/groovy/lib/python2.7/dist-packages/genpy/message.py", line 532, in _get_message_or_service_class
    raise ValueError("message type is missing package name: %s"%str(message_type))
ValueError: message type is missing package name: time

It looks like this could be fixed by inserting a new case around line 420 of message.py, handling the case when base_type is a time type.

[dirk-thomas]

Can you please retry it with a current checkout of rospy? The commit e8e0f3e might already solve your use case.

[astaa-nrec]

Thank you. That solves our most important use cases.

It does not, however, handle the case when a list of ints or longs is supplied.

So this works fine:

>>> timeArray = TimeArray()
>>> genpy.message.fill_message_args(timeArray, [{'stamps':[{'secs':1}, {'secs':1, 'nsecs':1}, {}]}])
>>> timeArray
stamps: 
  - 
    secs: 1
    nsecs: 0
  - 
    secs: 1
    nsecs: 1
  - 
    secs: 0
    nsecs: 0

But this is still broken:

>>> timeArray = TimeArray()
>>> genpy.message.fill_message_args(timeArray, [{'stamps':[1,2,3]}])
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "genpy/message.py", line 513, in fill_message_args
    _fill_message_args(msg, msg_args[0], keys, '')
  File "genpy/message.py", line 461, in _fill_message_args
    _fill_val(msg, f, v, keys, prefix)
  File "genpy/message.py", line 431, in _fill_val
    _fill_message_args(inner_msg, el, prefix)
  File "genpy/message.py", line 475, in _fill_message_args
    raise ValueError("invalid msg_args type: %s"%str(msg_args))
ValueError: invalid msg_args type: 1

[dirk-thomas]

I am not sure if [{'stamps':[1,2,3]}] is even supposed to work. Can you point to any doc where this is mentioned?

[astaa-nrec]

I don't know whether it's documented, but it works for non-array fields:

>>> h = Header()
>>> genpy.message.fill_message_args(h, [{'stamp' : 1}])
>>> h
seq: 0
stamp: 
  secs: 0
  nsecs: 1
frame_id: ''

The logic that handles it is on line 394 of message.py :

       elif isinstance(def_val, TVal) and type(v) in (int, long):
            #special case to handle time value represented as a single number
            #TODO: this is a lossy conversion
            if isinstance(def_val, Time):
                setattr(msg, f, Time.from_sec(v/1e9))
            elif isinstance(def_val, Duration):                    
                setattr(msg, f, Duration.from_sec(v/1e9))
            else:
                raise MessageException("Cannot create time values of type [%s]"%(type(def_val)))

[dirk-thomas]

Can you please check if pull request #19 fixes your use case?

[astaa-nrec]

Yes, that fixes it.

[dirk-thomas]

Thanks for confirmation. Patch is merged and will be release with the next version of genpy.