Django - Update or create syntax assistance (error) - django

Question

I've followed the guide in the queryset documentation as per (https://docs.djangoproject.com/en/1.10/ref/models/querysets/#update-or-create) but I think im getting something wrong:
my script checks against an inbox for maintenance emails from our ISP, and then sends us a calendar invite if you are subscribed and adds maintenance to the database.
Sometimes we get updates on already planned maintenance, of which i then need to update the database with the new date and time, so im trying to use "update or create" for the queryset, and need to use the ref no from the email to update or create the record
#Maintenance
if sender.lower() == 'maintenance#isp.com':
print 'Found maintenance in mail: {0}'.format(subject)
content = Message.getBody(mail)
postcodes = re.findall(r"[A-Z]{1,2}[0-9R][0-9A-Z]? [0-9][A-Z]{2}", content)
if postcodes:
print 'Found Postcodes'
else:
error_body = """
Email titled: {0}
With content: {1}
Failed processing, could not find any postcodes in the email
""".format(subject,content)
SendMail(authentication,site_admins,'Unprocessed Email',error_body)
Message.markAsRead(mail)
continue
times = re.findall("\d{2}/\d{2}/\d{4} \d{2}:\d{2}", content)
if times:
print 'Found event Times'
e_start_time = datetime.strftime(datetime.strptime(times[0], "%d/%m/%Y %H:%M"),"%Y-%m-%dT%H:%M:%SZ")
e_end_time = datetime.strftime(datetime.strptime(times[1], "%d/%m/%Y %H:%M"),"%Y-%m-%dT%H:%M:%SZ")
subscribers = []
clauses = (Q(site_data__address__icontains=p) for p in postcodes)
query = reduce(operator.or_, clauses)
sites = Circuits.objects.filter(query).filter(circuit_type='MPLS', provider='KCOM')
subject_text = "Maintenance: "
m_ref = re.search('\[(.*?)\]',subject).group(1)
if not len(sites):
#try use first part of postcode
h_pcode = postcodes[0].split(' ')
sites = Circuits.objects.filter(site_data__postcode__startswith=h_pcode[0]).filter(circuit_type='MPLS', provider='KCOM')
if not len(sites):
#still cant find a site, send error
error_body = """
Email titled: {0}
With content: {1}
I have found a postcode, but could not find any matching sites to assign this maintenance too, therefore no meeting has been sent
""".format(subject,content)
SendMail(authentication,site_admins,'Unprocessed Email',error_body)
Message.markAsRead(mail)
continue
else:
#have site(s) send an invite and create record
for s in sites:
create record in circuit maintenance
maint = CircuitMaintenance(
circuit = s,
ref = m_ref,
start_time = e_start_time,
end_time = e_end_time,
notes = content
)
maint, CircuitMaintenance.objects.update_or_create(ref=m_ref)
#create subscribers for maintenance
m_ref, is the unique field that will match the update, but everytime I run this in tests I get
sites_circuitmaintenance.start_time may not be NULL
but I've set it?

Answer 1

If you want to update certain fields provided that a record with certain values exists, you need to explicitly provide the defaults as well as the field names.
Your code should look like this:
CircuitMaintenance.objects.update_or_create(default=
{'circuit' : s,'start_time' : e_start_time,'end_time' : e_end_time,'notes' : content}, ref=m_ref)
The particular error you are seeing is because update_or_create is creating an object because one with rer=m_ref does not exist. But you are not passing in values for all the not null fields. The above code will fi that.