Bson pretty print using Java MongoDb driver

Question

I am using the Mongo Aggregation Framework using the Java MongoDB driver, version 3.3. I have an aggregagtion pipeline, that is merely collection of type List<Bson>. I am trying to find a way to pretty print each stage of the pipeline.

Calling the toString method on each element is not sufficient, because each stages is an instance of a simple implementation of the Bson interface, which is SimplePipelineStage. This stupid class has not any override of the toString method.

The pipeline is created using factory methods of mongo java driver Aggregates class, like the following:

Aggregates.match(/* ... */)
Aggregates.project(/* ... */)
// And so on...

Javadoc can be found here.

How can I pretty print such objects? I know for sure that the type BasicDbObject has a smart toString implementation, but I cannot find a way to convert from Bson to BasicDbObject.

Thanks a lot in advance.

Answer 1

Googling a bit harder, I found a solution to pretty print a Bson instance. The trick is to convert it into an instance of BsonDocument, which has an implementation of the toString method that returns the string representation of the corresponding JSON.

Bson bson = Filters.gt("a", 10);
BsonDocument bsonDocument = bson.toBsonDocument(BsonDocument.class, MongoClient.DEFAULT_CODEC_REGISTRY);
System.out.println(bsonDocument);

The original link is the following: Converting Bson object to BsonDocument.