Masahiko AMANO
2c83073903
db/db.go: TxFromContext/ContextWithTx for transaction propagation, Querier interface (QueryRow/Query/Exec), ScanRow generic helper, ClampLimit/ClampOffset pagination guards. db/postgres/postgres.go: NewPool with ping validation, Transactor backed by pgxpool (BeginTx → fn → commit/rollback), connOrTx helper that returns the active transaction from context or falls back to pool. Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
71 lines
2.0 KiB
Go
71 lines
2.0 KiB
Go
// Package db provides shared helpers used by all database adapters.
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package db
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import (
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"context"
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"fmt"
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"github.com/jackc/pgx/v5"
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"github.com/jackc/pgx/v5/pgconn"
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)
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// txKey is the context key used to store an active transaction.
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type txKey struct{}
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// TxFromContext returns the pgx.Tx stored in ctx by the Transactor, along
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// with a boolean indicating whether a transaction is active.
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func TxFromContext(ctx context.Context) (pgx.Tx, bool) {
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tx, ok := ctx.Value(txKey{}).(pgx.Tx)
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return tx, ok
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}
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// ContextWithTx returns a copy of ctx that carries tx.
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// Called by the Transactor before invoking the user function.
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func ContextWithTx(ctx context.Context, tx pgx.Tx) context.Context {
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return context.WithValue(ctx, txKey{}, tx)
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}
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// Querier is the common query interface satisfied by both *pgxpool.Pool and
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// pgx.Tx, allowing repo helpers to work with either.
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type Querier interface {
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QueryRow(ctx context.Context, sql string, args ...any) pgx.Row
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Query(ctx context.Context, sql string, args ...any) (pgx.Rows, error)
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Exec(ctx context.Context, sql string, args ...any) (pgconn.CommandTag, error)
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}
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// ScanRow executes a single-row query against q and scans the result using
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// scan. It wraps pgx.ErrNoRows so callers can detect missing rows without
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// importing pgx directly.
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func ScanRow[T any](ctx context.Context, q Querier, sql string, args []any, scan func(pgx.Row) (T, error)) (T, error) {
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row := q.QueryRow(ctx, sql, args...)
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val, err := scan(row)
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if err != nil {
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var zero T
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if err == pgx.ErrNoRows {
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return zero, fmt.Errorf("%w", pgx.ErrNoRows)
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}
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return zero, fmt.Errorf("ScanRow: %w", err)
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}
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return val, nil
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}
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// ClampLimit enforces the [1, max] range on limit, returning def when limit
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// is zero or negative.
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func ClampLimit(limit, def, max int) int {
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if limit <= 0 {
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return def
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}
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if limit > max {
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return max
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}
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return limit
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}
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// ClampOffset returns 0 for negative offsets.
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func ClampOffset(offset int) int {
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if offset < 0 {
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return 0
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}
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return offset
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}
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