In a data acquisition system, I need to handle reports for sensor
channels that may not have anything connected to them. The relevant
fields in my table definition look like:
Field('f_ch1_value_double', type = 'double', default = None,
label = T("CH1")),
Field('f_ch2_value_double', type = 'double', default = None,
label = T("CH2")),
Field('f_ch3_value_double', type = 'double', default = None,
label = T("CH3")),
Field('f_ch4_value_double', type = 'double', default = None,
label = T("CH4")),
Field('f_ch5_value_double', type = 'double', default = None,
label = T("CH5")),
Field('f_ch6_value_double', type = 'double', default = None,
label = T("CH6")),
and I have a function that starts like this:
@service.json
def v2_data_insert(timestamp, sensorid,
ch1=None, ch2=None, ch3=None, ch4=None, ch5=None,
ch6=None,
flowrate=None, flowtemp=None, erate=None,
chargev=None, battv=None, sensorv=None):
db.t_v2_data[0] = dict(f_timestamp_datetime = timestamp,
f_sensor_reference = sensorid,
f_ch1_value_double = ch1,
f_ch2_value_double = ch2,
f_ch3_value_double = ch3,
f_ch4_value_double = ch4,
f_ch5_value_double = ch5,
f_ch6_value_double = ch6,
f_flow_rate_double = flowrate,
f_flow_temp_double = flowtemp,
f_energy_rate_double = erate,
f_battery_charger_double = chargev,
f_battery_volts_double = battv,
f_sensor_volts_double = sensorv)
Passing None to any of the channel arguments, e.g. ch1 = None, is
raising
ValueError: could not convert string to float: None
on the insert call even though null is allowed by the field
definition. I suspect this must be an issue with the way
urllib.urlencode() the dictionary containing the channel values before
the data is posted to my controller.
The process that sends the data is doing the following:
encodeddata = urllib.urlencode(data)
response = urllib2.urlopen(server + url, encodeddata)
where data is the dictionary that maps to the keyword arguments of
v2_data_insert().
I can hack around this issue by testing for 'None' as a string value
in the controller, but I'd be grateful for a more elegant soution.
Thanks,
Mike
