package com.company.sample.listener;

import com.company.sample.core.DiscountCalculator;
import com.company.sample.entity.*;
import com.haulmont.cuba.core.EntityManager;
import com.haulmont.cuba.core.listener.*;
import org.springframework.stereotype.Component;
import javax.inject.Inject;
import java.math.BigDecimal;

@Component("sample_OrderEntityListener")
public class OrderEntityListener implements
        BeforeInsertEntityListener<Order>,
        BeforeUpdateEntityListener<Order>,
        BeforeDeleteEntityListener<Order> {

    @Inject
    private DiscountCalculator discountCalculator; // a managed bean of the middle tier

    @Override
    public void onBeforeInsert(Order entity, EntityManager entityManager) {
        calculateDiscount(entity.getCustomer(), entityManager);
    }

    @Override
    public void onBeforeUpdate(Order entity, EntityManager entityManager) {
        calculateDiscount(entity.getCustomer(), entityManager);
    }

    @Override
    public void onBeforeDelete(Order entity, EntityManager entityManager) {
        calculateDiscount(entity.getCustomer(), entityManager);
    }

    private void calculateDiscount(Customer customer, EntityManager entityManager) {
        if (customer == null)
            return;

        // Delegate calculation to a managed bean of the middle tier
        BigDecimal discount = discountCalculator.calculateDiscount(customer.getId());

        // Merge customer instance because it comes to onBeforeInsert as part of another
        // entity's object graph and can be detached
        Customer managedCustomer = entityManager.merge(customer);

        // Set the discount for the customer. It will be saved on transaction commit.
        managedCustomer.setDiscount(discount);
    }
}

package com.company.sales.service;

import com.company.sales.entity.Customer;
import com.haulmont.cuba.core.EntityManager;
import com.haulmont.cuba.core.listener.BeforeInsertEntityListener;
import com.haulmont.cuba.core.listener.BeforeUpdateEntityListener;
import org.springframework.stereotype.Component;
import org.springframework.transaction.support.TransactionSynchronizationAdapter;
import org.springframework.transaction.support.TransactionSynchronizationManager;

@Component("sales_CustomerEntityListener")
public class CustomerEntityListener implements BeforeInsertEntityListener<Customer>, BeforeUpdateEntityListener<Customer> {

    @Override
    public void onBeforeInsert(Customer entity, EntityManager entityManager) {
        printCustomer(entity);
    }

    @Override
    public void onBeforeUpdate(Customer entity, EntityManager entityManager) {
        printCustomer(entity);
    }

    private void printCustomer(Customer customer) {
        System.out.println("In transaction: " + customer);

        TransactionSynchronizationManager.registerSynchronization(new TransactionSynchronizationAdapter() {
            @Override
            public void afterCommit() {
                System.out.println("After transaction commit: " + customer);
            }
        });
    }
}