Java Driver 3.6.0: Exception on watching ChangeStreams

[Tobi Nonymous]

Hi,

I want to try out getting a $changeStream of inserts into a collection, 

but when I try to run the following simple code an "IllegalStateException: Invalid Map type. Map must have two type parameters defined." is thrown (see end of post for stacktrace):

MongoClient mongoClient = MongoClients.create(new ConnectionString("mongodb://localhost:27017"));

MongoDatabase database = mongoClient.getDatabase("mydb");

MongoCollection<Document> collection = database.getCollection("some-collection");

collection.watch(asList(

                Aggregates.match(and(asList(

                        in("operationType", asList("insert")),

                        eq("fullDocument.even", 1L)))

                )));

I followed this short tutorial (https://blog.codecentric.de/en/2018/01/change-streams-mongodb-3-6/), so I guess normally this code should be working 

I am not sure what the problem is, I have tried the mongodb-driver and mongodb-driver-async libraries in version 3.6.0 and 3.6.1.

I also have included spring-boot-starter-data-mongodb-reactive, as I want to use the spring data repositories for most of the other queries. Can there be some conflict with that library?

I am not using MongoDB regularly, so I suspect the problem lying with me, but the ChangeStream feature seems to pretty new as well, so I couldn't really find anything on this particular issue on Google.

The following exception is raised (no matter which overloaded version of .watch I try to invoke):

java.lang.IllegalStateException: Invalid Map type. Map must have two type parameters defined.

at org.bson.codecs.pojo.TypeData$Builder.validate(TypeData.java:115) ~[bson-3.5.0.jar:na]

at org.bson.codecs.pojo.TypeData$Builder.build(TypeData.java:104) ~[bson-3.5.0.jar:na]

at org.bson.codecs.pojo.PojoBuilderHelper.getTypeData(PojoBuilderHelper.java:158) ~[bson-3.5.0.jar:na]

at org.bson.codecs.pojo.PojoBuilderHelper.getTypeData(PojoBuilderHelper.java:179) ~[bson-3.5.0.jar:na]

at org.bson.codecs.pojo.PojoBuilderHelper.configureClassModelBuilder(PojoBuilderHelper.java:69) ~[bson-3.5.0.jar:na]

at org.bson.codecs.pojo.ClassModelBuilder.<init>(ClassModelBuilder.java:59) ~[bson-3.5.0.jar:na]

at org.bson.codecs.pojo.ClassModel.builder(ClassModel.java:63) ~[bson-3.5.0.jar:na]

at com.mongodb.client.model.changestream.ChangeStreamDocumentCodec.<init>(ChangeStreamDocumentCodec.java:46) ~[mongodb-driver-core-3.6.0.jar:na]

at com.mongodb.client.model.changestream.ChangeStreamDocument.createCodec(ChangeStreamDocument.java:142) ~[mongodb-driver-core-3.6.0.jar:na]

at com.mongodb.async.client.ChangeStreamIterableImpl.<init>(ChangeStreamIterableImpl.java:62) ~[mongodb-driver-async-3.6.0.jar:na]

at com.mongodb.async.client.MongoCollectionImpl.createChangeStreamIterable(MongoCollectionImpl.java:378) ~[mongodb-driver-async-3.6.0.jar:na]

at com.mongodb.async.client.MongoCollectionImpl.watch(MongoCollectionImpl.java:350) ~[mongodb-driver-async-3.6.0.jar:na]

at com.mongodb.async.client.MongoCollectionImpl.watch(MongoCollectionImpl.java:345) ~[mongodb-driver-async-3.6.0.jar:na]

at com.mypackages.SomeController.test(SomeController.java:63) ~[classes/:na]

[Jeff Yemin]

From the stack trace it looks like you're depending on bson-3.5.0.jar.  Please test again using bson-3.6.0.jar instead.

Regards,

Jeff

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[Jeff Yemin]

From the stack trace it looks like you're depending on bson-3.5.0.jar.  Please test again using bson-3.6.0.jar.

Regards,

Jeff

[Tobi Nonymous]

Good catch, thank you! (must come from somewhere inside the spring deps, as the poms of the mongodb-driver and async-driver reference 3.6.0)

The stacktrace is gone, but I am receiving the following error now:

The $changeStream stage is only supported on replica sets' on server localhost:27017. The full response is { "ok" : 0.0, "errmsg" : "The $changeStream stage is only supported on replica sets", "code" : 40573, "codeName" : "Location40573"

That means if I want to use this feature I have to turn my local mongo installation into a replica set?

[Jeff Yemin]

Yes, that's correct.  Change streams work off the oplog, which is present in replica sets but absent in standalones.

For a local mongo installation, you can create a single member replica set.  See this gist for an example.

Regards,

Jeff

[Tobi Nonymous]

Great link, thanks a lot for your help!