[wouter90]

Snapshot rows already contain database values. Exporting a Doctrine JSON type causes the raw JSON string to be encoded again during restoration, changing objects and arrays into strings. Other types can likewise receive values already converted by the database.

Use the string type for columns whose binding type is STRING so restoration preserves their stored representation. Keep the existing handling for other binding types.

Cover JSON, datetime and text conversion in the unit suite and verify an export/import round trip, including JSON scalars and SQL NULL. Document running the functional regressions through a Core checkout.

[CybotTM]

I tested the fix on TYPO3 Core main. The change to DatabaseAccessor does what it should. The new functional test fails without the fix and passes with it on SQLite, PostgreSQL, MariaDB and MySQL. Without the fix, only the JSON column differs: the restore encodes every value a second time, so 42 becomes "42".

I approve. These points are suggestions:

1. Unit test: keep only the JSON case. The plain text case passes with and without the fix. The database datetime case fails without the fix only because a unit test uses the Doctrine DateTimeType. In a TYPO3 run, ConnectionPool replaces datetime with the TYPO3 DateTimeType, which keeps strings unchanged. The functional test shows the same result: the created_at column comes back unchanged on main too.
2. Description: the sentence "Other types can likewise receive values already converted" is not true for datetime in TYPO3. CONTRIBUTING.rst also asks for an issue link, steps to reproduce and the results of the Core test runs.
3. Backport to branch 9: branch 9 has the same lookupName() and bulkInsert() code. TYPO3 13.4 requires ^9.2.1 and TYPO3 14.3 requires ^9.7.0. Recent bugfixes, for example 480a74d, went to main, 9.
4. CI: the CI of this repository does not run the functional test, because ci.yml runs only -s unit. A manual step is acceptable, but please state it in the description.

[CybotTM]

Follow-up to my review above. If you prefer to keep all three unit test cases, use the inline suggestion below instead of my earlier suggestion to delete two of them.