Let's start aggregating and computing values for groups of data in our report model.
This an example of "Total Sales Of Each Product"
class GroupByIntro(SlickReportView):
report_model = SalesLineTransaction
date_field = 'transaction_date'
group_by = 'product'
# We can group_by a foreign key or date field
columns = ['name',
SlickReportField.create(method=Sum, field='value', name='value__sum', verbose_name=_('Total sold $'))
# a Slick Report Field is responsible for carrying on the needed calculation(s).
]