Develop Reference

How to annotate strings in django objects

I want to concatinate first name + last name but i'm getting 0 as a value of full name
What I'm trying to do is this
Customer.objects.annotate(full_name=F('first_name') + F('last_name')).filter(full_name='Filan Fisteku')

from django.db.models.functions import Concat
ss = Customer.objects.annotate(full_name=Concat('first_name', Value(' '), 'last_name')).filter(full_name='Filan Fisteku')

Cannot filter my Django model depence on created_date

I am trying to do a chart. My database has created_date. I am getting product data every day about 150 times and I want to see a daily increase and decrease of my data. I have no problem with my front end and Django-template (I try manual data and it works well) I just want to see the last 7 days chart.
When I use Products.objects.filter(created_dates=days) filter method I am getting empty Queryset.
I already try created_dates__gte=startdate,created_dates__lte=enddate it return empty Queryset to.
I also try created_dates__range to there is no answer too.
I just get data from created_dates__gte=days but I don't want these data.
view.py
from datetime import date,timedelta
import datetime
def data_chart(request):
data = []
week_days = [datetime.datetime.now().date()-timedelta(days=i) for i in range (1,7)]
for days in week_days:
product_num = Products.objects.filter(created_dates=days)
date =days.strftime("%d.%m")
item = {"day": date,"value":len(product_num)}
data.append(item)
return render(request, 'chartpage.html', {'data': data})
In my database, I have thousands of data and my daily data about 150. My created_dates column format like this.
created_dates col:
2020-10-19 09:39:19.894184
So what is wrong with my code?. Could you please help?

You are trying to compare DateTimeField type (created_dates) with Date type (week_days is list of days) so maybe You should try __date lookup.
product_num = Products.objects.filter(created_dates__date=days)
https://docs.djangoproject.com/en/3.0/ref/models/querysets/#date
Furthermore maybe You should consider start using Count() database function with group by instead of iterating over days.
Here is great explanation:
https://stackoverflow.com/a/19102493/5160341

You should be able to do this with a single aggregation query:
import datetime
from django.db.models import Count
def data_chart(request):
cutoff = datetime.date.today() - datetime.timedelta(days=7)
raw_data = (
Products.objects.filter(created_dates__gte=cutoff)
.values_list("created_dates__date")
.annotate(count=Count("id"))
.values_list("created_dates__date", "count")
)
data = [{"day": str(date), "value": value} for (date, value) in raw_data]
return render(request, "chartpage.html", {"data": data})

For filtering data in Django, build dynamic query for multiple columns

I have to filter data from model based on the run time values. I am getting 5 values via query string. My querystring is like below:
http://127.0.0.1:8000/personal/search/?month=&year=&account=&deliveryManagedFrom=&marketmName=
So, I want to include all or none of the values in the filter so that it displays the desired result. Below is the filter query which I am writing:
sum_tt_count = NetworkRelatedInformation.objects.filter(month=month, year=year, account_id=account, account__deliveryManagedFrom=deliveryManagedFrom, account__marketName=market).aggregate(Sum('tt_count'))
totalttcount = sum_tt_count['tt_count__sum']
It is working well in case, all the values have been provided.
In case, if any value is blank, it should not consider that value and display output as per other filter criteria.
Pls suggest how to implement an OR filter with 5 data inputs. It is not necessary that all 5 data inputs have values . So the value can be None or the value in the querystring

Filter the request for non-empty values and then use dictionary expansion to do the query.
q = {k:v for k, v in request.GET.items() if v}
sum_tt_count = NetworkRelatedInformation.objects.filter(**q).aggregate(Sum('tt_count'))

You can do it using Q object
from django.db.models import Q
NetworkRelatedInformation.objects.filter(Q(month__isnull=True) | Q(month=month), Q(year__isnull=True) | Q(year=year)).aggregate(Sum('tt_count'))

For handling the None values i have to explicitly write the below code.
account = request.GET.get('account')
if account is '':
account = None
month = request.GET.get('month')
if month is '':
month = None
year = request.GET.get('year')
if year is '':
year = None
sum_alarm_count = NetworkRelatedInformation.objects.filter(Q(month=month) | Q(year=year) | Q(account_id=account)) \
.aggregate(Sum('alarm_count'))
totalalarmcount = sum_alarm_count['alarm_count__sum']

Django - Iterate over queryset and add static values

In the following queryset I am filtering planned hours per week (displayval is my week in this queryset) by employee. I would like to add an item for planned hours = 0 when the employee has no hours planned for a week I'm filtering by.
What's the easiest way to achieve this?
def DesignHubR(request):
emp3_list = Projectsummaryplannedhours.objects.values_list('displayval', 'employeename')
.filter(businessunit='a')
.filter(billinggroup__startswith='PLS - Project')
.filter(Q(displayval=sunday2)|Q(displayval=sunday))
.annotate(plannedhours__sum=Sum('plannedhours'))
emp3 = map(lambda x: {'date': x[0], 'employee_name': x[1], 'planned_hours': x[2]}, emp3_list)
context = {'sunday': sunday, 'sunday2': sunday2, 'emp3': emp3}
return render(request,'department_hub_ple.html', context)

I think that you can use the Coalesce(*expressions, **extra) function to solve your problem.
Accepts a list of at least two field names or expressions and returns the first non-null value (note that an empty string is not considered a null value).
So your query will be looking like:
from django.db.models import Sum, Value
from django.db.models.functions import Coalesce
emp3_list = \
Projectsummaryplannedhours.objects.\
filter(
Q(businessunit='a') &
Q(billinggroup__startswith='PLS - Project') &
(Q(displayval=sunday2) | Q(displayval=sunday))
).\
annotate(plannedhours__sum=Coalesce(
Sum('plannedhours'), Value(0)
)
).\
values_list('displayval', 'employeename')
See https://docs.djangoproject.com/en/1.9/ref/models/database-functions/#coalesce for more information.
This will help you to get plannedhours__sum = 0 if no entries to sum exists. If you also want to add additional parameter to each entry where plannedhours__sum = 0 you can use Django conditional expression.Read about Case expression for more information (https://docs.djangoproject.com/en/1.11/ref/models/conditional-expressions/#case).
Case() accepts any number of When() objects as individual arguments. Other options are provided using keyword arguments. If none of the conditions evaluate to TRUE, then the expression given with the default keyword argument is returned. If a default argument isn’t provided, None is used.
from django.db.models import Sum, Value, IntegerField
from django.db.models.functions import Coalesce
emp3_list = \
Projectsummaryplannedhours.objects.\
filter(
Q(businessunit='a') &
Q(billinggroup__startswith='PLS - Project') &
(Q(displayval=sunday2) | Q(displayval=sunday))
).\
annotate(plannedhours__sum=Coalesce(
Sum('plannedhours'), Value(0)
),
x=Case(When(plannedhours__sum=0, then=Value(0)),
output_field=IntegerField())
).\
values_list('displayval', 'employeename')
This will give you additional parameter x equals 0 if planned hours = 0 and None elsewhere. You can also filter emp3_list by annotated values.
As a result you can pass your queryset to a template context = {'sunday': sunday, 'sunday2': sunday2, 'emp3': emp3_list}, iterate over it there and get the attributes you need:
for q in emp3_list:
print(q[0], q[1], q[2])
Hope it will help you.

how to edit the form with data from the models

views.py
Editrow = KEBReading.objects.get(id=id)
print Editrow.datetime_reading
event_full_datetime=datetime(Editrow.datetime_reading.year,
Editrow.datetime_reading.month,
Editrow.datetime_reading.day,
Editrow.datetime_reading.hour,
Editrow.datetime_reading.minute,
Editrow.datetime_reading.second)
date = event_full_datetime.year, event_full_datetime.month, event_full_datetime.day
time = event_full_datetime.hour, event_full_datetime.minute
print date
print time
form = KEBReading_form(instance=Editrow)
in my models i have a datetime field. but in my forms i have a separate date and time field. but when i want to edit a row my variable Editrow has datetime value how do i populate the form with separate date and time while passing the instance(Editrow)
form = KEBReading_form(instance=Editrow)

First, you should understand how to use widgets for form fields. Then, just use SplitDateTimeWidget.