zambotn zambotn - 9 months ago 52
Python Question

Custom columns using Django admin

I have a model

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

subject | year | quarter | sales |
----------------------------------
1 | 2010 | 1 | 20 |
1 | 2010 | 2 | 100 |
1 | 2010 | 3 | 100 |
1 | 2010 | 4 | 20 |
1 | 2011 | 1 | 30 |
1 | 2011 | 2 | 50 |
1 | 2011 | 4 | 40 |
2 | 2010 | 1 | 30 |
2 | 2010 | 2 | 20 |
[..-GO ON this way...]


I want to have a django-admin table, in read-only having columns (
current year = 2011, quarter = 1
)

subject | sales current year | sales current quarter | sales last year | sales current quarter last year |
----------------------------------------------------------------------------------------------------------
1 | 110 | 30 | 240 | 20
[AND SO ON]


The question is: It is possible do that using django-admin? What's the way out?

Answer Source

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')