Auto-configure a MessageConverter for Rabbit if one exists in the context

[0xSalman]

Hey there,

This is a feature request. Could you please add a property i.e., spring.rabbitmq.message-converter and use it to set message converter on rabbit template and listener when auto configuring them. Thank you

[wilkinsona]

I'm not keen on using a property to configure a MessageConverter as it's not clear how the converter would be created. For example, what would happen if you want to use a ContentTypeDelegatingMessageConverter? How would you set its default converter or its delegates?

If you want to create a RabbitTemplate with a specific converter, you should declare your own @Bean for it. You can still use the auto-configured ConnectionFactory:

@Bean
public RabbitTemplate rabbitTemplate(ConnectionFactory connectionFactory) {
    RabbitTemplate template = new RabbitTemplate(connectionFactory);
    template.setMessageConverter(…);
    return template;
}

It's not so easy to configure a converter on the listener container as creating it isn't as straightforward. You could post-process the SimpleRabbitListenerContainerFactory bean, but that's not a very elegant solution. Perhaps there's something we can do to make it easier to customize. /cc @snicoll

[snicoll]

There is the same request for the JMS support and I was waiting for @ConditionalOnSingleCandidate to actually land in our code base first. The deal is that if there is only one MessageConverter we automatically associate it to the component we create.

How does that sound?

[snicoll]

See #4284

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[snicoll]

I'll take that as a yes. I don't like the idea of providing a configuration entry for that anyway.

[0xSalman]

@snicoll when you say a MessageConverter is available, I'm assuming you mean MessageConverter bean is available. I supposes it's a good work around. Thanks

[snicoll]

Yes. I don't really see what you mean by workaround though.

[0xSalman]

I was alluding towards the difference between configuring with a property vs creating a MessageConverter bean.

[snicoll]

In that case, I think configuring via a property is a bad idea (programming by properties). Note that as of 1.3.3 there is a new service you can use to quickly create your own container factory, see RabbitListenerContainerFactoryConfigurer

[0xSalman]

When you say configuring/programming via property is a bad idea, are you referring to this particular case or is that your take in general?

Thanks for pointing out RabbitListenerContainerFactoryConfigurer - it was helpful.

While configuring my own SimpleRabbitListenerContainerFactory, I noticed that RabbitAnnotationDrivenConfiguration is checking, whether this bean is missing, by name. Don't you think it would be better to use class reference (SimpleRabbitListenerContainerFactory.class) instead?

[snicoll]

Let's not start a chat here please, there's gitter for that. The check on name is on purpose as we are configuring the default factory and that's how the implementation looks it up .