feat(mappers): Stream name can now be accessed in __alias__ context of stream maps

[holly-evans]

Description

Allow users to reference the stream name in stream maps alias fields, under a special key:

{
    "stream_maps": {
        "*": {
            "__alias__": "'raw_' + __stream_name__"
        },
}

Related

• Closes feat: Access stream name in __alias__ #2700
• Similar to feat: Support using the stream name or alias in the context of a stream map #2283 but __alias__ was not an evaluated field before now

---

📚 Documentation preview 📚: https://meltano-sdk--2701.org.readthedocs.build/en/2701/

[codspeed-hq]

CodSpeed Performance Report

Merging #2701 will not alter performance

_{Comparing holly-evans:issue-2283-use-stream-name-in-alias (40ffd19) with main (9bf104e)}

Summary

✅ 6 untouched benchmarks

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 90.50%. Comparing base (9bf104e) to head (40ffd19).

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #2701   +/-   ##
=======================================
  Coverage   90.50%   90.50%           
=======================================
  Files          62       62           
  Lines        4994     4994           
  Branches      974      974           
=======================================
  Hits         4520     4520           
  Misses        328      328           
  Partials      146      146           

☔ View full report in Codecov by Sentry.
📢 Have feedback on the report? Share it here.

[holly-evans]

I am swallowing NameNotDefined errors here to support existing __alias__ configurations. Since __alias__ was not previously evaluated, it contains plain strings - which the evaluator tries to read as python objects.

For instance, { "__alias__": "aliased_stream" } will produce NameNotDefined. It would need single quotes to avoid this, like { "__alias__": "'aliased_stream'" }, which is a breaking change. Instead I'm just passing the expression as a string in these cases.

Please let me know what you think

[edgarrmondragon]

I think this makes sense. Thanks for being mindful of breaking changes 🙂

[edgarrmondragon]

This looks great, thanks @holly-evans!