fix mysql introspection json columns

[aiprojectchiwa]

Summary

Fix MySQL/MariaDB introspection in Prisma Studio when the introspection query returns aggregated columns as a JSON string instead of an array.

This prevents Studio from crashing with errors like:

• a.sort is not a function
• columns.sort is not a function

Root cause

Some MySQL-compatible backends (notably MariaDB variants) can return the json_arrayagg(...) result as a string payload. The adapter assumed columns was always already an array and called .sort() directly.

Fix

• Normalize columns before sorting
• Parse JSON string payloads when needed
• Keep the existing behavior unchanged for proper array results
• Add a regression test covering the string-returning case

Verification

Validated on Node 24.13.0 with:

• pnpm typecheck
• pnpm exec eslint data/mysql-core/adapter.ts data/mysql-core/introspection-hardening.test.ts
• pnpm test:data
• pnpm build
• pnpm check:exports

[TanNhatCMS]

@sorenbs Why has this serious error remained unresolved for such a long time?

[sorenbs]

Hi @aiprojectchiwa — thanks for digging into this and for the clean regression test. Since this was opened we root-caused the MariaDB failures further: the introspection SQL itself is invalid on MariaDB (cast(... as json) is a syntax error there, and pre-10.5 lacks json_arrayagg entirely), so string-payload parsing alone can't fully fix #1367/#1511. #1547 addresses it at the SQL level (MariaDB-specific aggregation via flavor detection) and includes transport-agnostic string-payload normalization equivalent to your fix, verified against real MariaDB 10.4 and 10.11. We'll close this PR once #1547 lands — thank you for moving the diagnosis forward; the string-payload observation was a genuinely useful clue.

[sorenbs]

Closing as discussed — #1547 has landed on main with the SQL-level MariaDB fix (one row per column, no aggregation) plus transport-agnostic string-payload normalization covering the case you diagnosed. Thanks again @aiprojectchiwa for moving this forward; the string-payload observation genuinely helped pin down the root cause.