Atomic updates in streaming expressions?

[Markus Kalkbrenner <ma...@biologis.com>]

Hi,

Solr supports atomic updates as described at https://lucene.apache.org/solr/guide/7_6/updating-parts-of-documents.html#atomic-updates

But I wonder how to create a streaming expression that does atomic updates. We want to search for documents matching a given criteria and update a particular of them.
If I do a „full“ update it works, but I have no idea about how to run an atomic update.
For example I try to set all fieldB to „foo“, this full update works

commit(
  update(
    select(
      export( … ),
      id,
      fieldA,
      val(foo) as fieldB
    )
)

Something like this doesn’t:

commit(
  update(
    select(
      export( … ),
      id,
      val({„set“: foo}) as fieldB
    )
)

Any ideas?

Markus