Custom columns using Django admin

Question

I have a model Data, associated to a table like this (The model Data is made up of only IntegerField):

subject | year | quarter | s         


        

Answer 1

Something like this should work (untested):

# models.py
class Data(models.Model):
    year = models.DateField()
    sales = models.IntegerField()
    # ...

    def sales_current_year(self):
        return self.model._default_manager.get_queryset().filter(year=2012).annotate(Sum('sales'))

 # admin.py
 class DataAdmin(admin.ModelAdmin):
      list_display = ('sales_current_year',)

Answer 2

You can use methods on your Model or your ModelAdmin as items for list_display. See: https://docs.djangoproject.com/en/dev/ref/contrib/admin/#django.contrib.admin.ModelAdmin.list_display

Since these are methods that might be useful outside the admin, as well, I'd suggest adding them to your Model.

from django.db.models import Sum

class Data(models.Model):
    ...

    # Method used by `get_current_year_sales` and `get_last_year_sales`
    # to stay DRY. Not for use directly in admin.
    def get_year_sales(self, year):
        qs = self.model._default_manager.filter(year=year)
        sales_agg = qs.aggregate(Sum('sales'))
        return sales_agg['sales__sum']

    # Method used by `get_current_quarter_sales` and `get_last_quarter_sales`
    # to stay DRY. Not for use directly in admin.
    def get_quarter_sales(self, year, quarter):
        qs = self.model._default_manager.filter(year=year, quarter=quarter)
        sales_agg = qs.aggregate(Sum('sales'))
        return sales_agg['sales__sum']

    def get_current_year_sales(self):
        return self.get_year_sales(datetime.now().year)
    get_current_year_sales.short_description = 'Sales (Current Year)'

    def get_last_year_sales(self):
        return self.get_year_sales(datetime.now().year-1)
    get_last_year_sales.short_description = 'Sales (Last Year)'

    def get_current_quarter_sales(self):
        # Determine current quarter logic here as `current_quarter`
        # `quarter_year` will likely be same as current year here,
        # but will need to be calculated for previous quarter
        return self.get_quarter_sales(quarter_year, current_quarter)
    get_current_quarter_sales.short_description = 'Sales (Current Quarter)'

    def get_current_quarter_sales(self):
        # Logic here to determine last quarter as `last_quarter`
        # Logic to determine what year last quarter was in as `quarter_year`
        return self.get_quarter_sales(quarter_year, last_quarter)
    get_last_quarter_sales.short_description = 'Sales (Last Quarter)'

The short_description attribute determines what the admin will show as the row header for these methods. So, once you have all this in place, you need only modify your ModelAdmin's list_display attribute like:

class DataAdmin(admin.ModelAdmin):
    ...
    list_display = ('subject', 'get_current_year_sales', 'get_last_year_sales', 'get_current_quarter_sales', 'get_last_quarter_sales')