Hello Django community,
I'm pretty new to Django and I'm getting stuck on the following issue.
I have a model defined as follows :
class temp_db(models.Model):
date = models.DateTimeField()
tempext = models.DecimalField(max_digits=4, decimal_places=2)
tempeau = models.DecimalField(max_digits=4, decimal_places=2)
humid = models.DecimalField(max_digits=4, decimal_places=2)
def __str__(self):
return str(self.date)
temp_db is being update every two minutes with a new entry thanks to a
dedicated python script.
I'm trying to develop a website page which would constantly show the last
value recorded in the table temp_db.
I would like to use ajax to retrieve the last entry (and you will
understand : without refreshing my webpage)
I've been consulting many tutorials to understand ajax and I think I'm
pretty ok with the way to do that from the client side.
>From a django standpoint; I'm getting trouble in transferring the last
entry of my table to the client. I think that json could help me but when
I'm trying to convert my entry into json with the following view code...
def myview1(request):
end_range = datetime.now()
range = timedelta(days=1)
beg_range = end_range - range
chart = temp_db.objects.filter(date__gte=beg_range)
last_entry = chart.latest('date')
data = serializers.serialize('json', last_entry)
return JsonResponse(data, safe=False)
...Django returns the following error :
Internal Server Error: /myview1/
Traceback (most recent call last):
File
"/home/pi/.virtualenvs/django/local/lib/python2.7/site-packages/django/core/handlers/exception.py",
line 41, in inner
response = get_response(request)
File
"/home/pi/.virtualenvs/django/local/lib/python2.7/site-packages/django/core/handlers/base.py",
line 187, in _get_response
response = self.process_exception_by_middleware(e, request)
File
"/home/pi/.virtualenvs/django/local/lib/python2.7/site-packages/django/core/handlers/base.py",
line 185, in _get_response
response = wrapped_callback(request, *callback_args, **callback_kwargs)
File "/home/pi/Projects/dashboard/views.py", line 55, in myview1
data = serializers.serialize('json', last_entry)
File
"/home/pi/.virtualenvs/django/local/lib/python2.7/site-packages/django/core/serializers/__init__.py",
line 129, in serialize
s.serialize(queryset, **options)
File
"/home/pi/.virtualenvs/django/local/lib/python2.7/site-packages/django/core/serializers/base.py",
line 80, in serialize
for count, obj in enumerate(queryset, start=1):
TypeError: 'temp_db' object is not iterable
I guess that the problem is that one single entry is trying to be
serialized since when I'm trying to serialize temp_db.objects.all(). -> it
works. Maybe json is not the the way to do this but the only thing I would
like to do is to properly get my object from a client side and use it like
Myentry.tempext in the Js code of the client webpage
Thanks in advance for your help.
Stéphane
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