[kolkov]

This release makes Upsert() actually work on MySQL, adds model-level upserts (#95) and locking reads, and fixes a transaction bug that could silently lose writes.

A few things worth calling out before upgrading:

• Transactional() / TransactionalContext(): if the context was canceled while the callback ran, the transaction was rolled back but the call returned nil. It now returns the context error. If your code got nil in that situation, those writes were in fact lost.
• MySQL Upsert() used to send only the INSERT part to the server, so updating an existing key never worked. On all databases the update part now copies the proposed row (EXCLUDED.col / VALUES(col)) and leaves the constraint columns out. On PostgreSQL this means BEFORE INSERT triggers now apply on the update path too, and expression values are evaluated once.
• Locking reads (ForUpdate(), ForShare(), ForUpdateSkipLocked()) must be built from a transaction (tx.Select()); building one from a DB returns an error, on SQLite too.
• TableName() with a pointer receiver is now used for values and slices (e.g. All(&rows) without From()). Code that silently depended on the snake-case fallback will query a different table.

Changelog

Added

• ModelQuery.Upsert(attrs...): inserts a model or updates the row with the same primary key, on MySQL, PostgreSQL and SQLite (#95). Fields are chosen as for Insert()/Update(); fields passed to Exclude() are neither inserted nor updated; the primary key is never updated; a zero single-column primary key is left out of the insertion (auto-increment). The primary key field is not filled after the call
• Upsert() for SQLite (INSERT ... ON CONFLICT (...) DO UPDATE SET ..., SQLite 3.24.0+)
• Locking reads: SelectQuery.ForUpdate(), ForShare() and ForUpdateSkipLocked() append FOR UPDATE, FOR SHARE or FOR UPDATE SKIP LOCKED after ORDER BY/LIMIT/OFFSET. A locking read must be built from a transaction (tx.Select()): from a DB the query returns an error on every database, SQLite included, since the lock would be released as soon as the statement ends. Inside a transaction the clause is left out for SQLite (no row locks); an error for SQL Server and Oracle, and when combined with Union(), GroupBy() or Distinct(). Optional LockQueryBuilder interface for custom query builders (not added to QueryBuilder, so existing implementations keep compiling)
• Errors.Unwrap() []error, so errors.Is and errors.As see each error of the list (e.g. the callback's error when Transactional() also failed to roll back)

Fixed

• Data loss: Transactional() and TransactionalContext() returned nil when the context was canceled while the callback ran. database/sql had already rolled the transaction back, so the callback's writes were lost while the caller was told they were committed. They now return the context error (context.Canceled / context.DeadlineExceeded). A callback that ends the transaction itself with tx.Commit() or tx.Rollback() and returns nil still gets nil
• MySQL Upsert() executed a plain INSERT: the ON DUPLICATE KEY UPDATE clause and its parameters were shown by SQL() but never sent to the server, so an existing key failed with a duplicate-key error (the same bug was fixed for PostgreSQL in #70)
• PostgreSQL Upsert() without constraint columns generated ON CONFLICT DO UPDATE without a conflict target, which PostgreSQL rejects; it now returns an error before executing (SQLite likewise)
• Upsert() with no column left to update besides the constraint columns generated an empty update clause; it now returns an error before executing
• GetTableName() (the default DB.TableMapper) ignored a TableName() method with a pointer receiver when given a struct value or a slice of struct values, e.g. db.Select().All(&[]Customer{}) without From(), and fell back to the snake-case type name. Code that relied on the fallback name will now query the table returned by TableName()
• SQLite: Like() and the other LIKE expressions never matched an escaped % or _ (e.g. Like("name", "50%") did not match "50% off"): the values are escaped with a backslash, but SQLite has no default LIKE escape character. An ESCAPE '\' clause is now added on SQLite only (MySQL and PostgreSQL use the backslash by default)

Changed

• Upsert() leaves the constraint columns out of the update part on every database. On MySQL constraints was ignored before: now a row matched through another unique index keeps its own values in the constraint columns (e.g. its primary key). On PostgreSQL the conflict columns were assigned their own values, a no-op except for UPDATE OF triggers and case-insensitive collations
• Upsert() (and ModelQuery.Upsert()) now update the existing row from the proposed row — col=EXCLUDED.col on PostgreSQL and SQLite, col=VALUES(col) on MySQL — instead of binding every value a second time. The update stores exactly what the insert would have stored, and each value is sent once. PostgreSQL behaviour change: BEFORE INSERT triggers now apply on the update path too (before, the update stored the values as passed), and an expression value such as nextval(...), random() or a function with side effects is evaluated once instead of twice (before, the second evaluation was stored and a sequence lost a value). On MySQL, VALUES() is deprecated since 8.0.20 (warning 1287) but is the only form that works on MySQL 5.7, 8 and 9 and on MariaDB

Not included

• Dependency updates. The newer versions of go-sql-driver/mysql (v1.10.1), filippo.io/edwards25519 (v1.2.0) and stretchr/objx (v0.8.0) require Go 1.24+, while ozzo-dbx still supports Go 1.22 (CI runs 1.22 and 1.23). They will come with a minimum Go version bump.
• Upsert with update-side expressions (counters like hits = hits + 1) and DO NOTHING; batch upsert.

Testing

• Unit tests for the generated SQL of all dialects, plus tests for the transaction fix with a fake database/sql driver.
• New MySQL 8 integration tests: upserts (a second unique key, a composite unique key with Exclude(), a NULL in a unique column, a BEFORE INSERT trigger, an expression evaluated once), locking reads (a second FOR UPDATE times out, SKIP LOCKED skips locked rows, two concurrent workers claim disjoint rows), a canceled transaction commits nothing, and LIKE with an escaped %.
• SQLite integration tests on modernc.org/sqlite (pure Go, test-only dependency of the integration module): an upsert expression is evaluated once per conflicting row.
• A new non-required CI job runs the integration suite on the newest MySQL release (mysql:innovation), to catch an eventual removal of VALUES().

Closes #95

[codecov]

Codecov Report

❌ Patch coverage is 99.15966% with 1 line in your changes missing coverage. Please review.
✅ Project coverage is 91.30%. Comparing base (a6134e4) to head (9600144).

Files with missing lines	Patch %	Lines
tx.go	92.30%	1 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##           master     #117      +/-   ##
==========================================
+ Coverage   86.45%   91.30%   +4.85%     
==========================================
  Files          16       16              
  Lines        1514     1588      +74     
==========================================
+ Hits         1309     1450     +141     
+ Misses        155       97      -58     
+ Partials       50       41       -9     

Flag	Coverage Δ
integration	57.24% <78.15%> (+10.94%)	⬆️
unit	74.24% <99.15%> (+10.90%)	⬆️

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