Drools example with spreadsheets tutorial

This is an  industrial strength extension to Drools with Decision tables (Excel spreadsheet).

The drool file: @{variable_name} read from spreadsheet values. Others are from Java classes and objects.

//read from an excel spreadsheet
template header
rules
group
inCashTransactionNm
inAnalysisCd
inTransactionTypeCd
inTransactionSubTypeCd
transactionTypeCd
transactionSubTypeCd
incomeSubTypeCd
analysisCd
audAmount
fxGainAndLoss

package com.myapp.calc;

//... 

global DroolsHelper droolsHelper;
global BankAccountService bankAccountService;
global StockTransactionService stockTransactionService;

template "CashTransaction"

rule "@{rules}_@{row.rowNumber}"
    activation-group "@{group}"
    salience -@{row.rowNumber}
    when
       cashTransaction : CashTransaction(true
                                         ,cashTransactionNm in (@{inCashTransactionNm})
                                         ,analysisCd in (@{inAnalysisCd})
                                         )
       bankAccount : BankAccount() from bankAccountService.getBankAccount(cashTransaction.getBankAccountId())
       stockTransaction : StockTransaction(getTransactionTypeCd() != null, transactionTypeCd.getTypeCode() in (@{inTransactionTypeCd}), transactionSubTypeCd.getTypeCode() in (@{inTransactionSubTypeCd})) from stockTransactionService.findByPortfolio(cashTransaction.portfolioId, cashTransaction.sourceTransactionId)
    then
       Transaction transaction = new Transaction(); // create a new object
       transactionsExtract.add(transaction);
       transaction.setRuleActivated("@{rules}_@{row.rowNumber}");
       transaction.setAssetCode(bankAccount.getAccountCd());
       transaction.setTransactionId(Long.valueOf(cashTransaction.getSourceTransactionId()));
       transaction.setTransactionDtTm(cashTransaction.getAccountingDt());
       transaction.setValueAud(droolsHelper.@{audAmount}(cashTransaction));
       deTransaction.setForeignExchangeGainsAndLosses(@{fxGainAndLoss}(cashTransaction));
        
end

end template

Define the method that invokes the rules.

  //....
  public List<Transaction> calcCash(int accountId)
    {
        LOG.info(String.format("Calculating : calcCash"));
        
        List<Transaction> transactions = new ArrayList<Transaction>();
        
  //read cash transactions from the database
        List<CashTransaction> cashTransactions = cashTransactionService.findByAccountId(accountId);
        
        
        for (CashTransaction cashTransaction : cashTransactions)
        {
            if (cashTransaction.getAnalysisCd() != null)
            {
                @SuppressWarnings("rawtypes")
                List<Command> cmds = new ArrayList<Command>();
                
    //make things available to drools file defined above
                cmds.add(CommandFactory.newSetGlobal("transactionsExtract", new ArrayList<Transaction>(), true));
                cmds.add(CommandFactory.newSetGlobal("bankAccountService", bankAccountService));
                cmds.add(CommandFactory.newSetGlobal("stockTransactionService", stockTransactionService));
                cmds.add(CommandFactory.newSetGlobal("droolsHelper", DroolsHelper));
                cmds.add(CommandFactory.newInsert(cashTransaction));
                
    //execute drools rules
                ExecutionResults results = ksession.execute(CommandFactory.newBatchExecution(cmds));
                
    List<Transaction> trans = (List<Transaction>) results.getValue("transactionsExtract");
                
                transactions.addAll(trans);
            }
        }

Finally, if the value of audAmount = "cash" the DroolsHelper static method invoked will be as shown below

    public static BigDecimal cash(CashTransaction transaction)
    {
        return cashTransaction.getCashValuePortfolio();
    }