You need to make it iterable, so there are two ways to do it.
One is to let it become a list with single object while another one is to
use filter so the result will be a QuerySet.
In your case will be the first one.
Stéphane Manguette於 2019年1月15日星期二 UTC+8上午9時26分14秒寫道：
>
> 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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