Unsupported $$ROOT aggregation expression

[bsautel]

As suggested here, I gave a try to mongo-java-server to replace fongo which seems to be no longer maintained and does not work with the 3.8 MongoDB Java driver.

First, I would like to thank you @bwaldvogel and all the other contributors for working on this project. Using the wire protocol seems to be a more reliable method as mocking the Java MongoDB driver as Fongo does since each implementation change in the driver can break the tool.

I ran all my tests using mongo-java-server and I noticed two blocking issues. I will report the other one in another ticket.

In an aggregation pipeline, I use the grouping operator and the $$ROOT expression that references the whole object, unlike ${field} which references a field of the object. It is documented here.

I get no error telling that it is unsupported but the field which should contain the result of this expression is null.

I tried to use the ${field} syntax and it seems to be supported. It would probably be necessary to extend this syntax to support the $$ROOT expression and maybe the other $$ specific expressions detailed in the documentation.

[bwaldvogel]

Thanks for reporting this issue!
It should be fixed in version 1.9.6.

[bsautel]

It works with the 1.9.6 version.

Thanks for your reactivity! You fixed the three issues I reported so fast!

Thanks to the 1.9.6 release, I could finish the Spring Boot 2.1.0 migration of my application! That's awesome! Congratulations!