class TotalProductSales(ReportView):
    report_title = _("Product Sales Quantity and Value [no auto load]")
    report_description = _("We compute the report over *two* fields `quantity and `value`."
                           "Results only load after you press Filter")
    report_model = SalesTransaction
    date_field = "date"
    group_by = "product"
    columns = [
        "name",
        ComputationField.create(Sum, "quantity", verbose_name="Total quantity sold", is_summable=False),
        ComputationField.create(Sum, "value", name="sum__value", verbose_name="Total Value sold $"),
    ]
    auto_load = False  # Require the user to press the filter, useful if the report is resource demanding

    chart_settings = [
        Chart(
            "Total sold $",
            Chart.BAR,
            data_source=["sum__value"],
            title_source=["name"],
        ),
        Chart(
            "Total sold $ [PIE]",
            Chart.PIE,
            data_source=["sum__value"],
            title_source=["name"],
        ),
    ]