class GroupByCustomQueryset(ReportView):
    report_model = SalesTransaction
    report_title = _("Group By Custom Queryset")
    report_description = _("Replaces automatic group-by with three crafted querysets (big, small, medium)."
                           "`format_row()` substitutes readable labels for the row's numeric index.")
    date_field = "date"

    group_by_custom_querysets = [
        SalesTransaction.objects.filter(product__size__in=["big", "extra_big"]),
        SalesTransaction.objects.filter(product__size__in=["small", "extra_small"]),
        SalesTransaction.objects.filter(product__size="medium"),
    ]
    group_by_custom_querysets_column_verbose_name = _("Product Size")

    columns = [
        "__index__",
        ComputationField.create(Sum, "value", verbose_name=_("Total Sold $"), name="value"),
    ]

    chart_settings = [
        Chart(
            title="Total sold By Size $",
            type=Chart.BAR,
            data_source=["value"],
            title_source=["__index__"],
        ),
    ]

    def format_row(self, row_obj):
        # Put the verbose names we need instead of the integer index
        index = row_obj["__index__"]
        if index == 0:
            row_obj["__index__"] = "Big"
        elif index == 1:
            row_obj["__index__"] = "Small"
        elif index == 2:
            row_obj["__index__"] = "Medium"
        return row_obj