How to report errors after streaming has started?

[jblashka]

I ran into lightblue-platform/lightblue-mongo#381 earlier, which caused my stream to return no results. But the client didn't throw an exception or indicate to me in any way that there was an error the occurred while processing the results. All I saw was that my streaming query resulted in no documents returned, but when I stepped through the query execution with a debugger I saw that the returned JSON contained:

...errors":[{"objectType":"error","context":"rest/FindCommand/containerImageRPMManifest/findAndStream(containerImageRPMManifest:1.0.0-SNAPSHOT)/mongo:find","errorCode":"mongo-crud:TooManyResults","msg":"17581"}]}

If I wasn't actively watching the results from my query and I wasn't aware that this query should have had results, I wouldn't have known there was a problem. Without setting some error flag or throwing some exception I'm concerned that some error while streaming results could occur and it would be silently consumed by lightblue and there'd be no way to report that an error occurred.

[jblashka]

Adding onto this. No exceptions get thrown if I query an unknown version of metadata either.

[paterczm]

@jblashka, can't reproduce your example with unknown version.

/rest/data/find/entity/#.#.#?stream=true returns

"errors": [
        {
            "objectType": "error",
            "context": "rest/FindCommand/entity/findAndStream(entity:#.#.#)/getEntityMetadata(entity:#.#.#)",
            "errorCode": "mongo-metadata:UnknownVersion",
            "msg": "entity:#.#.#"
        }

[paterczm]

Realized that the response above does not have status set, probably this is why lightblue-client is confused. Merging lightblue-platform/lightblue-core#814 should solve the issue.