AX7 FormDataSource Level OnValidating EventHandler and get all records in different datasource

class NEC_RetailPeriodicDiscountFormEventHandler
{

    /// <summary>
    ///
    /// </summary>
    /// <param name="sender"></param>
    /// <param name="e"></param>
    [FormDataFieldEventHandler(formDataFieldStr(RetailPeriodicDiscount, RetailPeriodicDiscountLine, DiscountPercentOrValue), FormDataFieldEventType::Validating)]
    public static void DiscountPercentOrValue_OnValidating(FormDataObject sender, FormDataFieldEventArgs e)
    {
        InventTable                             inventTable;
        InventTableModule                       inventTableModule;
        //RetailGroupMemberLine                   retailGroupMemberLine;
        EcoResProduct                           ecoResProduct;
        FormRun                                 formRun = sender.datasource().formRun();
       
        FormDataSource                          RetailDiscountLineMixAndMatch_ds = FormRun.dataSource(formDataSourceStr(RetailPeriodicDiscount, RetailPeriodicDiscountLine_RetailDiscountLineMixAndMatch));
        RetailDiscountLineMixAndMatch           RetailDiscountLineMixAndMatch = RetailDiscountLineMixAndMatch_ds.cursor();
        FormDataFieldCancelEventArgs            args = e as FormDataFieldCancelEventArgs;
        FormDataSource                          formDataSource = sender.datasource();
        RetailPeriodicDiscountLine              retailPeriodicDiscountLine = formDataSource.cursor();
        FormReferenceGroupControl               RetailGroupMemberLine_Product = formRun.design(0).controlName('RetailGroupMemberLine_Product');
       
        if(RetailDiscountLineMixAndMatch.discountType  == retaildealpricediscountpctbase::dealprice)
        {
            select  inventTableModule
                exists join inventTable
                    where inventTableModule.ItemId == inventTable.ItemId
                    && inventTableModule.ModuleType == ModuleInventPurchSales::Sales
                    exists join EcoResProduct
                        where inventTable.Product == RetailGroupMemberLine_Product.value();
            if (inventTableModule.ItemId  && inventTableModule.Price < retailPeriodicDiscountLine.DiscountPercentOrValue)
            {
                boolean doCancel =!checkFailed("Deal price cannot exceeds the base sale price");
                args.cancel(doCancel);
            }
        }
    }

    /// <summary>
    ///
    /// </summary>
    /// <param name="sender"></param>
    /// <param name="e"></param>
    [FormDataFieldEventHandler(formDataFieldStr(RetailPeriodicDiscount, RetailPeriodicDiscountLine_RetailDiscountLineOffer, discAmount), FormDataFieldEventType::Validating)]
    public static void discAmount_OnValidating(FormDataObject sender, FormDataFieldEventArgs e)
    {
        InventTable                     inventTable;
        InventTableModule               inventTableModule;
        RetailPeriodicDiscountLine      retailPeriodicDiscountLine;
        RetailGroupMemberLine           retailGroupMemberLine;
        EcoResProduct                   ecoResProduct;
        FormDataFieldCancelEventArgs    args = e as FormDataFieldCancelEventArgs;

        FormRun                         formRun = sender.datasource().formRun();
        FormDataSource                  RetailDiscountlineoffer_ds = sender.datasource();
        RetailDiscountLineOffer         retailDiscountLineOffer = RetailDiscountlineoffer_ds.cursor();
        FormReferenceGroupControl       RetailGroupMemberLine_Product = formRun.design(0).controlName('RetailGroupMemberLine_Product');

        if(retailDiscountLineOffer.discountMethod == RetailDiscountOfferLineDiscMethodBase::AmountOff)
        {
            select  inventTableModule
                exists join inventTable
                    where inventTableModule.ItemId == inventTable.ItemId
                    && inventTableModule.ModuleType == ModuleInventPurchSales::Sales
                    exists join EcoResProduct
                        where inventTable.Product == RetailGroupMemberLine_Product.value();
            if (inventTableModule.ItemId  && inventTableModule.Price < retailDiscountLineOffer.discAmount)
            {
                boolean doCancel =!checkFailed("Cash discount Amount cannot exceeds the base sale price");
                args.cancel(doCancel);
            }
        }
    }