Not able to set custom converters to MongoDbMessageStore

[debesay]

Affects Version(s): <Spring Integration version>
spring-integration-mongodb
5.1.2.RELEASE

As explained in https://stackoverflow.com/questions/56215529/configurablemongodbmessagestore-failed-to-instantiate-org-springframework-messa#
there is a need to be able to add custom converters to MongoDbMessageStore or successfully inject ConfigurableMongoDbMessageStore with a MongDbTemplate containing custom converters.
Please assist.

[artembilan]

Well, that is really why we have introduced a ConfigurableMongoDbMessageStore: the way when you can inject your own MongoTemplate with any possible external configuration.

We can't abuse internally a provided instance because that one can be used in any other place.
So, if you provide a MongoTemplate we don't mutate it internally. Here is a logic:

if (this.mongoTemplate == null) {
			if (this.mappingMongoConverter == null) {
				this.mappingMongoConverter = new MappingMongoConverter(new DefaultDbRefResolver(this.mongoDbFactory),
						new MongoMappingContext());
				this.mappingMongoConverter.setApplicationContext(this.applicationContext);
				List<Object> customConverters = new ArrayList<>();
				customConverters.add(new MessageToBinaryConverter());
				customConverters.add(new BinaryToMessageConverter());
				this.mappingMongoConverter.setCustomConversions(new MongoCustomConversions(customConverters));
				this.mappingMongoConverter.afterPropertiesSet();
			}
			this.mongoTemplate = new MongoTemplate(this.mongoDbFactory, this.mappingMongoConverter);
		}

So, you should consider to add those MessageToBinaryConverter and BinaryToMessageConverter into your external MongoTemplate instance.

The MongoDbMessageStore is so tied to the messaging that its internal MongoTemplate, together with those internal converters, is fully not feasible for any other scenarios.

But as Gary said in the mentioned SO question, there is no reason to worry about a ConfigurableMongoDbMessageStore: just enough to provide a MongoDbFactory and the first one will take care about the proper configuration for an internal MongoTemplate!

[garyrussell]

@artembilan But can't we add a hook to allow him to add his custom converter to the template? From the SO comments..

I tried the MongoDbMessageStore first but it could not decode/encode a field property in my pojo of type java.time.ZonedDateTime. I have added a custom converter for this to the MongoTemplate, which I am able to use with my MongoRepository dao with no problem. But I have not found a way to use these custom converters with the MongoDbMessageStore, hence trying out the ConfigurableMongoDbMessageStore

Seems like addCustomConverters() should be possible. No?

[artembilan]

Yes, that we can do: add setCustomConverters(Object... converters) into the MongoDbMessageStore, but I'm against similar approach for the ConfigurableMongoDbMessageStore, since we can't mutate injected MongoTemplate

[garyrussell]

Agreed.