convert to different javatype when use @RabbitListener annonation [AMQP-461]

[spring-operator]

Alex Young opened AMQP-461 and commented

I have a problem with @RabbitListener annonation when convert message. I produce a message with User.class in A project and want to consume it in B project with a Map.class, because there is no User.class in B project. But I found the json converter can only convert to User.class before invoking the method and if I use Map to accept it the adapter omit the whole method. That's wired, it's hard to make different project convert to same javabean especially the project use different platforms like nodejs or .NET.

Why not inject to method and convert by param's type just like Spring MVC did?

This is the code:

configuration:

@Configuration
@EnableRabbit
public class RabbitConfig{

	@Autowired CustomJackson mapper;

	Jackson2JsonMessageConverter converter;
	
	@Bean
    public ConnectionFactory connectionFactory() {
        CachingConnectionFactory connectionFactory = new CachingConnectionFactory("localhost");
        return connectionFactory;
    }

    @Bean
    public AmqpAdmin amqpAdmin() {
        return new RabbitAdmin(connectionFactory());
    }

    @Bean
    public RabbitTemplate rabbitTemplate() {
    	RabbitTemplate rt = new RabbitTemplate(connectionFactory());
    	rt.setMessageConverter(converter());
        return rt;
    }
    
    public Jackson2JsonMessageConverter converter() {
    	if(converter == null) converter = new Jackson2JsonMessageConverter();
    	converter.setJsonObjectMapper(mapper);
        return converter;
    }

    @Bean
    public SimpleRabbitListenerContainerFactory rabbitListenerContainerFactory() {
    	SimpleMessageListenerContainer container = new SimpleMessageListenerContainer();
        SimpleRabbitListenerContainerFactory factory = new SimpleRabbitListenerContainerFactory();
        factory.setConnectionFactory(connectionFactory());
        factory.setMessageConverter(converter());
        return factory;
    }
    
    @Bean
    public Queue myQueue() {
       return new Queue("core/user/myquery");
    }


}

producer in project A:

@Service
public class Producer {

	@Autowired RabbitTemplate rt;

	public void sendMessage (){
		User user = new User();
		user.id = "aaa";
		user.name = "yec";
		user.orders = new ArrayList<Order>();
		Order o = new Order();
		o.id = "1";
		o.name = "order1";
		user.orders.add(o);
		rt.convertAndSend("core/user/myquery", user);
	}

}

consumer in project B:

@Component
public class Consumer {

    @RabbitListener(queues = "core/user/myquery")
    public void processOrder(Map<String,String> user) {
    	System.out.println("user:" + user.toString());
    }
}

---

Affects: 1.4.1

Issue Links:

• Consider a Mechanism to Convey @RabbitListener Parameter Type to Jackson2JsonMessageConverter [AMQP-549] #2109 Consider a Mechanism to Convey @RabbitListener Parameter Type to Jackson2JsonMessageConverter

1 votes, 4 watchers

[spring-operator]

Gary Russell commented

Please use Stack Overflow (spring-amqp tag) to ask questions. JIRA is for reporting bugs and requesting new features.

Set a ClassMapper on the converter to override the default behavior...

@Bean
public Jackson2JsonMessageConverter inboundConverter() {
	Jackson2JsonMessageConverter converter = new Jackson2JsonMessageConverter();
	converter.setClassMapper(new ClassMapper() {
		
		@Override
		public Class<?> toClass(MessageProperties properties) {
			return Map.class;
		}
		
		@Override
		public void fromClass(Class<?> clazz, MessageProperties properties) {
			throw new UnsupportedOperationException("this mapper is only for inbound");
		}
		
	});
	return converter;
}

[spring-operator]

Danilkovich Denis commented

Have a same problem. Found two solutions:

1. http://blog.james-carr.org/2011/01/31/json-message-marshalling-in-spring-amqp/
2. http://stackoverflow.com/questions/30770725/spring-boot-rabbitmq-mappingjackson2messageconverter-custom-object-conversion

To my mind both solutions were uncomfortable espessially when using @RabbitListener annonation. So I have my solution:

Here is my configuration:

@Configuration
@EnableRabbit
public class AMQPConfig {

    @Autowired
    private RabbitMQSettings rabbitMQSettings;

    @Bean
    public ConnectionFactory connectionFactory() {
        CachingConnectionFactory factory = new CachingConnectionFactory(rabbitMQSettings.getHost(), rabbitMQSettings.getPort());
        factory.setUsername(rabbitMQSettings.getUser());
        factory.setPassword(rabbitMQSettings.getPassw());
        return factory;
    }

    @Bean
    public AmqpTemplate template() {

        RabbitAdmin admin = new RabbitAdmin(connectionFactory());
        Queue queue = new Queue("abd.queue.nameChanged");
        admin.declareQueue(queue);
        DirectExchange exchange = new DirectExchange("abd.direct.exchange");
        admin.declareExchange(exchange);

        admin.declareBinding(BindingBuilder.bind(queue).to(exchange).with(queue.getName()));

        RabbitTemplate template = new RabbitTemplate(connectionFactory());
        template.setExchange(exchange.getName());
        template.setRoutingKey(queue.getName());
        template.setMessageConverter(this.messageConverter());
        return template;
    }

    @Bean
    public MessageConverter messageConverter() {
        Jackson2JsonMessageConverter converter = new Jackson2JsonMessageConverter();
        converter.setCreateMessageIds(true);
        return converter;
    }
}

My DTO objects has save structure:

@ToString
class UserDTO{
    String name;
    int age;

    UserDTO() {}

    UserDTO(String name, int age) {
        this.name = name
        this.age = age
    }
}

@ToString
class UserDTO2 {
    String name;
    int age;
}

Here is my listiner:

@Configuration
public class NameChangedListiner {

    @Autowired
    MessageConverter messageConverter;

    public <T> T convertToObject(Class<T> cls, Message message) {
        message.getMessageProperties().getHeaders().put("__TypeId__", cls.getCanonicalName());
        return (T) messageConverter.fromMessage(message);
    }

    @RabbitListener(queues = {"abd.queue.nameChanged"})
    public void onNameChanged(Message message) throws InterruptedException {
        UserDTO2 userDto2 = convertToObject(UserDTO2.class, message);
        UserDTO userDto = convertToObject(UserDTO.class, message);
    }
}

But why @RabbitListener can't make such a convertion behind the scenes? As a result it is not necessary to do any additional configurations which described in articles I found.

[spring-operator]

Gary Russell commented

See the new feature in 1.5.

It allows class-level @RabbitListener with multiple handler methods based on payload type.

We're expecting to release it before SpringOne in September, but there's a milestone available.

[spring-operator]

Artem Bilan commented

Looks like the latest changes to the type inferring have fixed this issue as well.

See #2109
and http://docs.spring.io/spring-amqp/docs/1.6.0.BUILD-SNAPSHOT/reference/html/_introduction.html#_json_messageconverter

Completed in the appropriate version.