[pox-dev] Accessing ofp_port_stats fields

[Murphy McCauley]

On Apr 23, 2014, at 1:54 PM, Alison Chan <chan7781 at kettering.edu> wrote:

> I am trying to access the port_no field of an ofp_port_stats reply
> object. printing the object suggests that it is an ofp_port_stats
> object, but trying to access its port_no field results in an
> AttributeError: 'list' object has no attribute 'port_no'. How do I
> access its port_no and other fields?

Well there's your problem. ;)  It's a list, not an ofp_port_stats.

> [16:24:42] erinacity:~/Code/pox
> alisonc $ ./pox.py openflow.of_01 py
> [snip startup crap]
> POX> import pox.openflow.libopenflow_01 as of
> POX>
> POX> def handle_port_stats(event):
> ...   print event.stats
> ...   print event.stats.port_no
> ...
> POX> core.openflow.addListenerByName("PortStatsReceived", handle_port_stats)
> (<class 'pox.openflow.PortStatsReceived'>, 14)
> POX> core.openflow.connections[1].send(of.ofp_stats_request(body=of.ofp_port_stats_request(port_no=of.OFPP_NONE)))
> POX> [<pox.openflow.libopenflow_01.ofp_port_stats object at
> 0x2a57ad0>, <pox.openflow.libopenflow_01.ofp_port_stats object at
> 0x2a57a10>, <pox.openflow.libopenflow_01.ofp_port_stats object at
> 0x2a57b50>]

And there's your list.  Of ofp_port_stats.

Try...
print [p.port_no for p in event.stats]

Or just print event.stats[0].port_no to print only the first one.

> ERROR:core:Exception while handling OpenFlowNexus!PortStatsReceived...
> Traceback (most recent call last):
>  File "/home/alisonc/Code/pox/pox/lib/revent/revent.py", line 231, in
> raiseEventNoErrors
>    return self.raiseEvent(event, *args, **kw)
>  File "/home/alisonc/Code/pox/pox/lib/revent/revent.py", line 278, in
> raiseEvent
>    rv = event._invoke(handler, *args, **kw)
>  File "/home/alisonc/Code/pox/pox/lib/revent/revent.py", line 156, in _invoke
>    return handler(self, *args, **kw)
>  File "<console>", line 3, in handle_port_stats
> AttributeError: 'list' object has no attribute 'port_no'
> 
> Cheers,
> -- 
> Alison Chan
> chan7781 at kettering.edu
> SMS: +1 909 278 7753
> Fax: +1 206 203 2793

-- Murphy