SilverioMG

# Use root/example as user/password credentials
version: '3.7'

services:

  mongo:
    image: mongo:6.0.8
    container_name: mongo
    restart: always
    environment:

SilverioMG

	@Test
	public void using_Map_and_FlatMap() {
		Person personTest = personRepository.getPersonTest();
		
		Integer stateCode = Optional.ofNullable(personTest)
				.flatMap(person -> person.getOptionalAddress())
				.map(address -> address.getState())
				.flatMap(state -> state.getOptionalCode())
				.orElseGet(() -> null);
		

SilverioMG

	@Test
	public void using_FlatMap() {
		Person personTest = personRepository.getPersonTest();
		
		Integer addressNumber = Optional.ofNullable(personTest)
				.flatMap(person -> person.getOptionalAddress())
				.flatMap(address -> address.getOptionalNumber())
				.orElseGet(() -> null);
		assertNotNull(addressNumber);
		assertEquals(addressNumber, personTest.getAddress().getNumber());

SilverioMG

	@Test
	public void using_Map() {
		Person personTest = personRepository.getPersonTest();
		
		Integer addressNumber = Optional.ofNullable(personTest)
				.map(person -> person.getAddress())
				.map(address -> address.getNumber())
				.orElseGet(() -> null);
		assertNotNull(addressNumber);
		assertEquals(addressNumber, personTest.getAddress().getNumber());

SilverioMG

package net.atopecode.optionals.model;

import java.util.Optional;

public class State {
	
	private String name;
	
	private Integer code;
	

SilverioMG

package net.atopecode.optionals.model;

import java.util.Optional;

public class Address {
	
	private String street;
	
	private Integer number;
	

SilverioMG

package net.atopecode.optionals.model;

import java.util.Optional;

public class Person {
	
	private String name;
	
	private String email;
	

SilverioMG

@Test
public void flatMapTest(){
	Person person = personRepository.getPersonTest();
    	String emailWithFlatMap = Optional.ofNullable(person)
			.flatMap((p -> Optional.ofNullable(p.getEmail()))) //Con 'flatMap()' hay que devolver un 'Optional<T>' con el resultado deseado.
			.orElse(null);
	System.out.println("Con faltMap(): " + emailWithFlatMap);
	assertEquals(emailWithFlatMap, person.getEmail());
}

SilverioMG

@Test
public void mapTest(){
	Person person = personRepository.getPersonTest();
	String emailWithMap = Optional.ofNullable(person)
			.map(person -> person.getEmail()) //Con 'map()' se hace un wrapper del resultado 'T' dentro de un objeto 'Optional<T>' automáticamente, pero nosotros devolvemos directamente el tipo 'T'.
			.orElse(null);
	System.out.println("Con map(): " + emailWithMap);
	assertEquals(emailWithMap, person.getEmail());
}

SilverioMG

	@Test
	public void getStateField_with_StateNotNull() {
		Person personWithState = personRepository.getPersonTest();
		String stateName = personWithState.getAddress().getState().getName();
		assertTrue(stateName != null);
		
		String stateNameOptional = Optional.ofNullable(personWithState)
				.map(person -> person.getAddress())
				.map(address -> address.getState())
				.map(state -> state.getName())