views.py

from .models import Carbon 
from django.db.models import Q 
from django.views.generic import ListView
from datetime import datetime 



class CarbonDataView(ListView):
    model = Carbon 
    context_object_name = 'carbon'
    template_name = 'carbon/chart.html'

    def get_context_data(self, **kwargs):
        context =  super().get_context_data(**kwargs)
        query = self.request.GET.get('q')
        context['date'] = Carbon.objects.values('reading_date').order_by('reading_date').distinct()
        if query:
            context['carbon'] = Carbon.objects.filter(
                Q(reading_date=datetime.strptime(query,"%Y,%b,%d"))
                )
            context['selected_date'] = datetime.strptime(query,"%Y,%b,%d")
        else:
             context['carbon'] = Carbon.objects.filter(
                Q(reading_date=datetime(2017,1,1))
            )
             context['selected_date'] = datetime(2017,1,1)
        return context



# class CarbonExportView()