Missing configuration or possible bug about int:router + List<MessageChannel>

[dr_pompeii]

Hello guys

I am working and testing the section Configuring a Router with Annotations where appear the follow snippet code

@Router
public MessageChannel route(Message message) {...}

@Router
public List<MessageChannel> route(Message message) {...}

@Router
public String route(Foo payload) {...}

@Router
public List<String> route(Foo payload) {...}

I tested each approach about the return type but the second does not work

For example if I work with List<String>

<int:router id="router" 
		input-channel="inicio"
  	        apply-sequence="true"
		method="metodoRouter01"							
		ref="myRouterSinAnnotationTres"	
/>

private List<String> listChannels;
	
public MyRouterConAnnotationTres(){
	listChannels = new ArrayList<String>();
	listChannels.add("dvdChannel");
	listChannels.add("instrumentoMusicalChannel");		
}
	
@Router
public List<String> metodoRouter01(Message<?> message){
			
	logger.info("... message: {}", message);
		
	return listChannels;		
}

It work fine

But If I work with List<MessageChannel>

<int:router id="router" 
		input-channel="inicio"
		apply-sequence="true"
		method="metodoRouter01"
		ref="myRouterSinAnnotationCuatro"	
				/>

private List<MessageChannel> listChannels;
	
private DirectChannel dvdChannel;	
private DirectChannel instrumentoMusicalChannel;
	
@Value("#{dvdChannel}")
public void setDvdChannel(DirectChannel dvdChannel) {
	this.dvdChannel = dvdChannel;
}	
	
@Value("#{instrumentoMusicalChannel}")
public void setInstrumentoMusicalChannel(DirectChannel instrumentoMusicalChannel) {
	this.instrumentoMusicalChannel = instrumentoMusicalChannel;
}
	
public MyRouterSinAnnotationCuatro(){
	listChannels = new ArrayList<MessageChannel>();
	listChannels.add(dvdChannel);
	listChannels.add(instrumentoMusicalChannel);
}
		
public List<MessageChannel> metodoRouter01(Message<?> message){
				
	logger.info("... message: {}", message);
	return listChannels;		
}

does not work I dont receive none exception

How I know it does not work?, simply I have two flow integration files

one working with List<String> and the second with List<MessageChannel>, each file has

<int:message-history/>

<int:wire-tap pattern="*" channel="logger" />
	
<int:logging-channel-adapter id="logger"								 
				 level="INFO"								 					 
				 log-full-message="true"	
				/>

For the case with List<String> I can see through the history for each Message sent, the follow history:

startChannel, router->outputchannel, some ServiceActivator, finalChannel

But with List<MessageChannel> I can see only the follow history for each Message sent it, everyone has the follow sequence:

startChannel, router->XXX

I mean with XXX that each Message<T> never left the router, what is wrong?

I have the same weird behaviour even If I work with List<DirectChannel>

Thanks in advanced

[dturanski]

The reason List<MessageChannel> is not working is because you are initializing the channel list in the constructor. This happens before Spring invokes the setters so listChannels = [null,null]. You need to do something like:

@PostConstruct
	public void init() {
		listChannels = new ArrayList<MessageChannel>();
		listChannels.add(dvdChannel);
		listChannels.add(instrumentoMusicalChannel);
	}

List<String> works because you are setting string literals.

[dr_pompeii]

Hello dturanski

Thanks so much for the explanation

Wooh this kind of error is unforgivable

The reason List<MessageChannel> is not working is because you are initializing the channel list in the constructor. This happens before Spring invokes the setters so listChannels = [null,null].

Yes I did realize with

for(MessageChannel messageChannel : listChannels){
			
	if(messageChannel==null)
		logger.error("++++++++++SI SOY NULL++++++++");
	else
		logger.info("-----------------NO SOY NULL-------------");
	}

and I forgot include resolution-required="true" to see the problem

List<String> works because you are setting string literals.

Yes, there is no need to wait some initialization or injection of dependencies by the container

I forgot by complete the order of work

1. creation target object (by its constructor)
2. setter injection and/or constructor injection

Thanks for your time

Best Regards