SOLR-8003: A glob followed by a raw value transformer now writes each matching field raw

[nick-boss-tech]

🤖 AI text below 🤖 (posted on behalf of Nick Shanin)

https://issues.apache.org/jira/browse/SOLR-8003

What happens today

A glob cannot take a raw value transformer, so fl=*_json:[json] returns a 400 error.

A request such as fl=*_json:[json] or fl=su*:[json] is rejected with a 400. The *_json form fails with a "fieldname parse error"; the su* form fails with an "undefined field" error naming su, the text before the *. The parser accepts a glob only when a space, a comma or the end of the string follows it (SolrReturnFields.java lines 307-316 at the merge-base). It then gives up on the glob (lines 332-333 at the merge-base). Today a raw transformer works only on one named field, so writing every _json field raw means listing each name.

What this change does

A glob followed by a raw value transformer now writes each matching field raw.

• fl=*_json:[json] and fl=su*:[json] are accepted. Each returned field whose name matches is written raw, under its own name (SolrReturnFields.java lines 318-347 at the head). A bare * before a raw transformer, such as fl=*:[json], is rejected with a 400 that names the named-glob form instead (lines 320-325).
• The response writer checks the marker against each field as it is written (TextResponseWriter.java lines 122-133). Only the JSON and XML writers do this (JSONWriter.java line 110, XMLWriter.java line 192). Other writers ignore it, as they already ignore [json] and [xml].
• A glob combined with another transformer, such as su*:[docid], still returns a 400 (lines 333-341).

Proof

A new test fails on the base code and passes with this change.

• TestRawTransformer.testGlobJsonTransformer (test lines 350-408) sends fl=id,su*:[json],link?:[json] and checks the raw output. It then sends fl=au*:[xml], which is not applied to a JSON response, and fl=su*:[docid], which returns a 400. On the base code the first request is rejected with a 400, so the test fails there.
• TestRawTransformer.testSuffixGlobJsonTransformer (test lines 411-454) sends fl=id,*_json:[json], the form used as the example above, parses the response, and checks that each returned document writes its payload_json field raw. It then sends fl=*:[json] and checks that the request is rejected with a 400. On the base code the *_json request is rejected with a 400, "Error parsing fieldname: Expected identifier at pos 0 str='*_json:[json]'", so this test fails there.
• Verified 2026-10-15 at head 85a8d32: TestRawTransformer 4 of 4. With the production file reverted to the previous head 17a5305, the class runs 4 tests with exactly one failure, the suffix-glob test, because the bare-star request is accepted there. On the base code the two glob tests fail, as the earlier verification at 17a5305 recorded.

Limits

Only the JSON writer is tested with a glob. Some combinations are not covered.

• Every glob request in the test uses wt=json. The XML writer is not tested with a glob.
• A glob combined with renameFields, and nested child documents, are not tested.

Changelog: changelog/unreleased/SOLR-8003-fl-glob-raw-transformer.yml

AI assistance

AI agents assisted with research, implementation, review, and drafting. Nick Shanin directed the work and takes responsibility for this contribution.