Insert into a table after inserting data using the admin Django

Question

I am new to Django...

I am inserting data into a table, lets call it the Bet table using the django admin. (Ie: Bets I made, where the fields are the game date, the result, how much I betted, if I won or lost the bet, etc...). However, I also want to know, at the end of each month, how much games I won, lost, how much I profited, etc. So I created the table MonthlyBets. What I want to do, is something similar to a DB trigger: Whenever I add a bet to the Bet table, using the django-admin, I want to add to the MonthlyBets table the profit I made, if I won or not, etc.

What's the best way to do this?

Seems to me that creating another table to hold the same data that is in the first table is redundant and unnecessary. Why not just create a view of the data in the first table? — smilebomb, Apr 08 '16 at 18:56

Lucas03 · Accepted Answer · 2016-04-08T19:21:33.097

Best way would be not to create MonthlyBets at all. You can get monthly records by calculation from your Bet model like in Section 2(renamed Bet to Tip).
Section 1
If you insist on creating MonthlyBets model, you can overwrite Django Admin save method. Or listen for post_save signal of Bet model. If new Bet object is created, update MonthlyBets.

Section 2 It is not very straightforward code, but it does calculate Yield, Count and Win Ratio for each month for Tip model.

for date in Tip.objects.datetimes('date_game', 'month', order='DESC'):
        date_filter['date_game__month'] = date.month
        date_filter['date_game__year'] = date.year
        date_yield, date_count, date_win = get_yield(date_filter)
        month_list.append({"month": date, "yield": date_yield,
                           "count": date_count,
                           "win": date_win})

And something like this in utils.py or wherever you keep your logic.

from django.db.models import Sum, F
from django.db import models as db_models
def get_yield(filter={}):
    """
    @kwargs filter options = date_game__month=month, date_game__year=year, sport__name=sport, etc
    :return: yield, all_tips_count, win_tips_count
    http://stackoverflow.com/questions/12165636/django-aggregation-summation-of-multiplication-of-two-fields
    """
    win_sum = Tip.objects.filter(result=Tip.WIN, **filter).aggregate(total=Sum(F('odds')*F('stake'),
                                                                               output_field=db_models.DecimalField()))['total']
    if win_sum==None:
        win_sum=0
    stake_sum = Tip.objects.filter(result__in=[Tip.WIN, Tip.LOST], **filter).aggregate(total=Sum('stake'))['total']
    if stake_sum==None:
        return 0, Tip.objects.filter(result__in=[Tip.WIN, Tip.LOST], **filter).count(),\
               Tip.objects.filter(result__in=[Tip.WIN], **filter).count()
    return (win_sum-stake_sum)/stake_sum * 100,\
            Tip.objects.filter(result__in=[Tip.WIN, Tip.LOST], **filter).count(),\
            Tip.objects.filter(result__in=[Tip.WIN], **filter).count()

Insert into a table after inserting data using the admin Django

1 Answers1